The r'-band luminosity function of Abell1367 a comparison with Coma

医学物理实验_山东大学中国大学mooc课后章节答案期末考试题库2023年1.日常生活中的表面吸附现象有：The surface adsorption phenomena in dailylife are as follows:参考答案:面粉洗葡萄Washing grapes with flour_活性炭过滤水Activated carbonfilter water_水面上的油膜Oil film on water2.杨氏弹性模量E仅决定于材料本身的性质，而与外力ΔF，物体的长度L以及截面积S的大小无关，它是表征固体材料性质的一个重要物理量。

Young's modulus of elasticity e is only determined by the properties of thematerial itself, but has nothing to do with the external force Δ F, the length L of the object and the cross section product S. It is an important physicalquantity to characterize the properties of solid materials.参考答案:正确3.精密度是与“真值”之间的一致程度，是系统误差与随机误差的综合。

Precision is the degree of consistency with "true value", and is the synthesis of systematic error and random error.参考答案:错误4.以下说法正确的是：Which statement below is correct参考答案:在一定的温度下，它的旋光率与入射光波长的平方成反比，且随波长的减少而迅速增大，这现象称为旋光色散。

1. 輻射束(joule/sec)2. 光束/光通量(lumen)3. 光度(Candela, cd)4. 輝度(cd/m 2)5. 照度(Lux)6. 光束發散度(radlux)7. 反射率(reflectivity)8. 電光源效率(power eff.)七、色度與CIE 色度座標色度座標之測定之測定之測定--發光學術語與基本概念發光光度學常用單位與定義電磁波於單位時間內所傳播的輻射能量(J/sec)或Watt F = KΦ (K為視覺度,其大小依波長而異,其最大值為100, F為光束2.光束/光通量(luminous, 單位:流明Lumen)光源所發出的總光量或單位時間內所通過的光量, 可用照度計加以量測3.光度I (Luminous intensity,單位為燭光Cd, candela)一光源在冇一方向所發出光的強度稱之為光度，假設dω為一微小立體角，其包含的光束為dF，則此光源箭頭方向的光度(I)為I = 光束/立體角= dF/dω所以dF= I dω此立體角內所有方向之光度I 則為I =dF/dω對均勻的點光源而言，，F (lumen) = 4πI (單位為燭光)對均勻的點光源而言其中4π為總立體角各種光源的輝度值(nit)太陽165 x 107月亮26 x 102蠟燭1 x 104藍空8 x 103水銀燈14 x 104日光燈6x 103-1x 104納氣燈(200W) 8 x1044. 輝度L (Brightness, 單位為nit 或nt = cd/m 2或stilb (sb), sb = cd/m 2由一特定的光源發出強度相同時由一特定的光源發出強度相同時，，其發光的面積越大者其發光的面積越大者，，則其輝度值越小越小。

某一截面的輝度L (nit)值，為其該方向的光度值I (cd)，以該截面的視面積A (m 2)除得之值除得之值，，以L 表示L = I (cd)/A (m 2) = nit or cd/m 2or stilb5. 照度E (Illumination Intensity,單位為Lux勒克斯)(Spectra colorimeter)380-780 nm(Lux meter)(color analyzer) 測量輝度值與色度值0.2 –999 cd/m2彩色分析儀彩色分析儀--輝亮度輝亮度((cd/m 2)、對比度對比度、、閃爍閃爍、、色度色度(x,y)(x,y)(x,y)值之測定值之測定Anatomy of Human Eyes1虹膜2角膜玻璃體4 Rods5 Cones 3 視網膜6 水晶體.7 瞳孔視神經Cones(解析度高有色彩分析能力) and rods(感光度高對低照暗輻極敏感)The distribution of cones and rods in the retina and where the retina is most sensitive to light (blue graph).Luminosity response of eyes–yellow-green is brighter or stronger response to eyes, than R and B.視網膜(3 types of cones )Providing high accuracy and the ability to measure absolute color, used in research areaSpectrophotometric method Tristimulus method Human eye Problems with difference betweenindividuals and memory characteristicsSmall size and portability, used for colordifference measurements and QC inspection3 sensors Spectral sensorsChromatic Adaptation（色彩的適應性）Chromatic Adaptation (色彩的適應性)Block diagram of basic components of a spectrophotometerA spectrophotometer is a device used to measure the intensity of radiation absorbed at different wavelengths by looking at the spectral reflectance, transmittance or emission.Inventor: Brace DeWitt; In 1935 Arthur Cobb Hardy received a patent for the spectrophotometer .The spectral luminous efficiency curvesScotopic (low light) vision system V’(λ):Driven by rod cells; unable to differentiate different λ’s; provides no saensation of colorsPhototopic (daytime) vision system V(λ) : Driven by cone cells; can differentiatedifferent λ’s: ctreate sensation of colors 507 nm 555 nm視覺函數V(λ), V’(λ)曲線1942與1951年根據亮年根據亮、、暗適應條件下暗適應條件下，，CIE 對200多位觀察者視覺的測定結果位觀察者視覺的測定結果，，分別推薦了標準的明標準的明視覺視覺(V(λ):峰值555 nm ，光譜光效能最高值K m (λ)=683lm/W )與暗視覺(V’(λ);峰值507 nm ，光譜光效能最高值K m ’(λ)1699=lm/W )函數曲線函數曲線。

中国天文学会天文学名词审定委员会第1-6批天文学名词的推荐译名The 1st - 6th Drafts for the Chinese-Translation of Astronomical Termsrecommanded byThe Astronomical Terminology Committee of the CASabsolute stability 绝对稳定性absorbing dust mass 致吸尘物质absorption trough 吸收槽abundance standard 丰度标准星accreting binary 吸积双星accretion column 吸积柱accretion flow 吸积流accretion mound 吸积堆accretion ring 吸积环accretion stream 吸积流acoustic mode 声模active binary 活动双星active chromosphere binary 活动色球双星active chromosphere star 活动色球星active optics 主动光学actuator 促动器Adams ring 亚当斯环adaptive optics 自适应光学additional perturbation 附加摄动AGB, asymptotic giant branch 渐近巨星支Alexis, Array of Low-Energy X-ray 〈阿列克希斯〉低能X 射线Imaging Sensors 成象飞行器AM Herculis star 武仙AM 型星amplitude spectrum 变幅谱angular elongation 距角anonymous galaxy 未名星系anonymous object 未名天体anti-jovian point 对木点annular-total eclipse 全环食aperture photometry 孔径测光APM, Automated Photographic Measuring 〈APM〉底片自动测量仪systemapoapse 远质心点apoapse distance 远质心距apogalacticon 远银心点apomartian 远火点apparent association 表观成协apparent luminosity function 视光度函数apparent superluminal motion 视超光速运动apsidal advance 拱线进动apsidal precession 拱线进动Arcturus group 大角星群area image sensor 面成象敏感器area photometry 面源测光area spectroscopy 面源分光argument of pericentre 近心点幅角ASCA, Advanced Satellite for Cosmology 〈ASCA〉宇宙学和天体物理学and Astrophysics 高新卫星asteroidal dynamics 小行星动力学asteroidal resonance 小行星共振asteroid family 小行星族asteroid-like object 类小行星天体asteroseismology 星震学astration 物质改造astroparticle physics 天文粒子物理学astrostatistics 天文统计学asymptotic branch 渐近支asymptotic branch giant 渐近支巨星atmospheric parameter 大气参数ATNT, Australia Telescope National 澳大利亚国立望远镜FacilityATT, Advanced Technology Telescope 〈ATT〉高新技术望远镜automated measuring machine 天文底片自动测量仪automatic photooelectric telescope 自动光电测光望远镜( APT )AXAF, Advanced X-ray Astrophysical 高新X射线天体物理台FacilityBaade's window 巴德窗Baade—Wesselink analysis 巴德—韦塞林克分析Baade—Wesselink mass 巴德—韦塞林克质量Baade—Wesselink method 巴德—韦塞林克方法Baade—Wesselink radius 巴德—韦塞林克半径background galaxy 背景星系Barnard's galaxy ( NGC 6822 ) 巴纳德星系barycentric dynamical time ( TDB ) 质心力学时Belinda 天卫十四Bianca 天卫八bidimensional spectrography 二维摄谱bidimensional spectroscopy 二维分光Big-Bang nucleosynthesis 大爆炸核合成binarity 成双性binary asteroid 双小行星binary flare star 耀变双星binary millisecond pulsar 毫秒脉冲双星binary protostar 原双星bioastronomy 生物天文学bipolar jet 双极喷流bipolar outflow 偶极外向流bipolar planetary nebula 双极行星状星云blazar 耀变体blazarlike activity 类耀活动blazarlike object 耀变体Black-eye galaxy ( M 64 ) 黑眼星系BL Lacertae object 蝎虎天体BL Lacertid 蝎虎天体blue compact galaxy ( BCG ) 蓝致密星系blue straggler 蓝离散星bolometric albedo 热反照率bolometric light curve 全波光变曲线bolometric temperature 热温度Bootes void 牧夫巨洞bow-shock nebula 弓形激波星云box photometry 方格测光broad-band imaging 宽波段成象broad-line radio galaxy ( BLRG ) 宽线射电星系buried channel CCD 埋沟型CCDButterfly nebula 蝴蝶星云BY Draconis star 天龙BY 型星BY Draconis variable 天龙BY 型变星CAMC, Carlsberg Automatic Meridian 卡尔斯伯格自动子午环Circlecannibalism 吞食cannibalized galaxy 被吞星系cannibalizing galaxy 吞食星系cannibalizing of galaxies 星系吞食carbon dwarf 碳矮星Cassegrain spectrograph 卡焦摄谱仪Cassini 〈卡西尼〉土星探测器Cat's Eye nebula ( NGC 6543 ) 猫眼星云CCD astronomy CCD 天文学CCD camera CCD 照相机CCD photometry CCD 测光CCD spectrograph CCD 摄谱仪CCD spectrum CCD 光谱celestial clock 天体钟celestial mechanician 天体力学家celestial thermal background 天空热背景辐射celestial thermal background radiation 天空热背景辐射central overlap technique 中心重迭法Centaurus arm 半人马臂Cepheid distance 造父距离CFHT, Canada-Franch-Hawaii Telecope 〈CFHT〉望远镜CGRO, Compton Gamma-Ray Observatory 〈康普顿〉γ射线天文台chaos 混沌chaotic dynamics 混沌动力学chaotic layer 混沌层chaotic region 混沌区chemically peculiar star 化学特殊星Christmas Tree cluster ( NGC 2264 ) 圣诞树星团chromosphere-corona transition zone 色球-日冕过渡层chromospheric activity 色球活动chromospherically active banary 色球活动双星chromospherically active star 色球活动星chromospheric line 色球谱线chromospheric matirial 色球物质chromospheric spectrum 色球光谱CID, charge injected device CID、电荷注入器件circular solution 圆轨解circumnuclear star-formation 核周产星circumscribed halo 外接日晕circumstellar dust disk 星周尘盘circumstellar material 星周物质circumsystem material 双星周物质classical Algol system 经典大陵双星classical quasar 经典类星体classical R Coronae Borealis star 经典北冕R 型星classical T Tauri star 经典金牛T 型星Clementine 〈克莱芒蒂娜〉环月测绘飞行器closure phase imaging 锁相成象cluster centre 团中心cluster galaxy 团星系COBE, Cosmic Background Explorer 宇宙背景探测器coded mask imaging 编码掩模成象coded mask telescope 编码掩模望远镜collapsing cloud 坍缩云cometary burst 彗暴cometary dynamics 彗星动力学cometary flare 彗耀cometary H Ⅱregion 彗状电离氢区cometary outburst 彗爆发cometary proplyd 彗状原行星盘comet shower 彗星雨common proper-motion binary 共自行双星common proper-motion pair 共自行星对compact binary galaxy 致密双重星系compact cluster 致密星团; 致密星系团compact flare 致密耀斑composite diagram method 复合图法composite spectrum binary 复谱双星computational astrophysics 计算天体物理computational celestial mechanics 计算天体力学contact copying 接触复制contraction age 收缩年龄convective envelope 对流包层cooling flow 冷却流co-orbital satellite 共轨卫星coplanar orbits 共面轨道Copernicus 〈哥白尼〉卫星coprocessor 协处理器Cordelia 天卫六core-dominated quasar ( CDQ ) 核占优类星体coronal abundance 冕区丰度coronal activity 星冕活动、日冕活动coronal dividing line 冕区分界线coronal gas 星冕气体、日冕气体coronal green line 星冕绿线、日冕绿线coronal helmet 冕盔coronal magnetic energy 冕区磁能coronal red line 星冕红线、日冕红线cosmic abundance 宇宙丰度cosmic string 宇宙弦cosmic void 宇宙巨洞COSMOS 〈COSMOS〉底片自动测量仪C-O white dwarf 碳氧白矮星Cowling approximation 柯林近似Cowling mechnism 柯林机制Crescent nebula ( NGC 6888 ) 蛾眉月星云Cressida 天卫九critical equipotential lobe 临界等位瓣cross-correlation method 交叉相关法cross-correlation technique 交叉相关法cross disperser prism 横向色散棱镜crustal dynamics 星壳动力学cryogenic camera 致冷照相机cushion distortion 枕形畸变cut-off error 截断误差Cyclops project 〈独眼神〉计划D abundance 氘丰度Dactyl 艾卫dark halo 暗晕data acquisition 数据采集decline phase 下降阶段deep-field observation 深天区观测density arm 密度臂density profile 密度轮廓dereddening 红化改正Desdemona 天卫十destabiliizing effect 去稳效应dew shield 露罩diagonal mirror 对角镜diagnostic diagram 诊断图differential reddening 较差红化diffuse density 漫射密度diffuse dwarf 弥漫矮星系diffuse X-ray 弥漫X 射线diffusion approximation 扩散近似digital optical sky survey 数字光学巡天digital sky survey 数字巡天disappearance 掩始cisconnection event 断尾事件dish 碟形天线disk globular cluster 盘族球状星团dispersion measure 频散量度dissector 析象管distance estimator 估距关系distribution parameter 分布参数disturbed galaxy 受扰星系disturbing galaxy 扰动星系Dobsonian mounting 多布森装置Dobsonian reflector 多布森反射望远镜Dobsonian telescope 多布森望远镜dominant galaxy 主星系double-mode cepheid 双模造父变星double-mode pulsator 双模脉动星double-mode RR Lyrae star 双模天琴RR 型星double-ring galaxy 双环星系DQ Herculis star 武仙DQ 型星dredge-up 上翻drift scanning 漂移扫描driving system 驱动系统dumbbell radio galaxy 哑铃状射电星系Du Pont Telescope 杜邦望远镜dust ring 尘环dwarf carbon star 碳矮星dwarf spheroidal 矮球状星系dwarf spheroidal galaxy 矮球状星系dwarf spiral 矮旋涡星系dwarf spiral galaxy 矮旋涡星系dynamical age 动力学年龄dynamical astronomy 动力天文dynamical evolution 动力学演化Eagle nebula ( M 16 ) 鹰状星云earty cluster 早型星系团early earth 早期地球early planet 早期行星early-stage star 演化早期星early stellar evolution 恒星早期演化early sun 早期太阳earth-approaching asteroid 近地小行星earth-approaching comet 近地彗星earth-approaching object 近地天体earth-crossing asteroid 越地小行星earth-crossing comet 越地彗星earth-crossing object 越地天体earth orientation parameter 地球定向参数earth rotation parameter 地球自转参数eccentric-disk model 偏心盘模型effect of relaxation 弛豫效应Egg nebula ( AFGL 2688 ) 蛋状星云electronographic photometry 电子照相测光elemental abundance 元素丰度elliptical 椭圆星系elliptical dwarf 椭圆矮星系emulated data 仿真数据emulation 仿真encounter-type orbit 交会型轨道enhanced network 增强网络equatorial rotational velocity 赤道自转速度equatorium 行星定位仪equipartition of kinetic energy 动能均分eruptive period 爆发周期Eskimo nebula ( NGC 2392 ) 爱斯基摩星云estimated accuracy 估计精度estimation theory 估计理论EUVE, Extreme Ultraviolet Explorer 〈EUVE〉极紫外探测器Exclamation Mark galaxy 惊叹号星系Exosat 〈Exosat〉欧洲X 射线天文卫星extended Kalman filter 扩充卡尔曼滤波器extragalactic jet 河外喷流extragalactic radio astronomy 河外射电天文extrasolar planet 太阳系外行星extrasolar planetary system 太阳系外行星系extraterrestrial intelligence 地外智慧生物extreme helium star 极端氦星Fabry-Perot imaging spectrograph 法布里-珀罗成象摄谱仪Fabry-Perot interferometry 法布里-珀罗干涉测量Fabry-Perot spectrograph 法布里-珀罗摄谱仪face-on galaxy 正向星系face-on spiral 正向旋涡星系facility seeing 人为视宁度fall 见落陨星fast pulsar 快转脉冲星fat zero 胖零Fermi normal coordinate system 费米标准坐标系Fermi-Walker transportation 费米-沃克移动fibre spectroscopy 光纤分光field centre 场中心field galaxy 场星系field pulsar 场脉冲星filter photography 滤光片照相观测filter wheel 滤光片转盘find 发见陨星finder chart 证认图finderscope 寻星镜first-ascent giant branch 初升巨星支first giant branch 初升巨星支flare puff 耀斑喷焰flat field 平场flat field correction 平场改正flat fielding 平场处理flat-spectrum radio quasar 平谱射电类星体flux standard 流量标准星flux-tube dynamics 磁流管动力学f-mode f 模、基本模following limb 东边缘、后随边缘foreground galaxy 前景星系foreground galaxy cluster 前景星系团formal accuracy 形式精度Foucaultgram 傅科检验图样Foucault knife-edge test 傅科刀口检验fourth cosmic velocity 第四宇宙速度frame transfer 帧转移Fresnel lens 菲涅尔透镜fuzz 展云Galactic aggregate 银河星集Galactic astronomy 银河系天文Galactic bar 银河系棒galactic bar 星系棒galactic cannibalism 星系吞食galactic content 星系成分galactic merge 星系并合galactic pericentre 近银心点Galactocentric distance 银心距galaxy cluster 星系团Galle ring 伽勒环Galilean transformation 伽利略变换Galileo 〈伽利略〉木星探测器gas-dust complex 气尘复合体Genesis rock 创世岩Gemini Telescope 大型双子望远镜Geoalert, Geophysical Alert Broadcast 地球物理警报广播giant granulation 巨米粒组织giant granule 巨米粒giant radio pulse 巨射电脉冲Ginga 〈星系〉X 射线天文卫星Giotto 〈乔托〉空间探测器glassceramic 微晶玻璃glitch activity 自转突变活动global change 全球变化global sensitivity 全局灵敏度GMC, giant molecular cloud 巨分子云g-mode g 模、重力模gold spot 金斑病GONG, Global Oscillation Network 太阳全球振荡监测网GroupGPS, global positioning system 全球定位系统Granat 〈石榴〉号天文卫星grand design spiral 宏象旋涡星系gravitational astronomy 引力天文gravitational lensing 引力透镜效应gravitational micro-lensing 微引力透镜效应great attractor 巨引源Great Dark Spot 大暗斑Great White Spot 大白斑grism 棱栅GRO, Gamma-Ray Observatory γ射线天文台guidscope 导星镜GW Virginis star 室女GW 型星habitable planet 可居住行星Hakucho 〈天鹅〉X 射线天文卫星Hale Telescope 海尔望远镜halo dwarf 晕族矮星halo globular cluster 晕族球状星团Hanle effect 汉勒效应hard X-ray source 硬X 射线源Hay spot 哈伊斑HEAO, High-Energy Astronomical 〈HEAO〉高能天文台Observatoryheavy-element star 重元素星heiligenschein 灵光Helene 土卫十二helicity 螺度heliocentric radial velocity 日心视向速度heliomagnetosphere 日球磁层helioseismology 日震学helium abundance 氦丰度helium main-sequence 氦主序helium-strong star 强氦线星helium white dwarf 氦白矮星Helix galaxy ( NGC 2685 ) 螺旋星系Herbig Ae star 赫比格Ae 型星Herbig Be star 赫比格Be 型星Herbig-Haro flow 赫比格-阿罗流Herbig-Haro shock wave 赫比格-阿罗激波hidden magnetic flux 隐磁流high-field pulsar 强磁场脉冲星highly polarized quasar ( HPQ ) 高偏振类星体high-mass X-ray binary 大质量X 射线双星high-metallicity cluster 高金属度星团;高金属度星系团high-resolution spectrograph 高分辨摄谱仪high-resolution spectroscopy 高分辨分光high - z 大红移Hinotori 〈火鸟〉太阳探测器Hipparcos, High Precision Parallax 〈依巴谷〉卫星Collecting SatelliteHipparcos and Tycho Catalogues 〈依巴谷〉和〈第谷〉星表holographic grating 全息光栅Hooker Telescope 胡克望远镜host galaxy 寄主星系hot R Coronae Borealis star 高温北冕R 型星HST, Hubble Space Telescope 哈勃空间望远镜Hubble age 哈勃年龄Hubble distance 哈勃距离Hubble parameter 哈勃参数Hubble velocity 哈勃速度hump cepheid 驼峰造父变星Hyad 毕团星hybrid-chromosphere star 混合色球星hybrid star 混合大气星hydrogen-deficient star 缺氢星hydrogenous atmosphere 氢型大气hypergiant 特超巨星Ida 艾达( 小行星243号)IEH, International Extreme Ultraviolet 〈IEH〉国际极紫外飞行器HitchhikerIERS, International Earth Rotation 国际地球自转服务Serviceimage deconvolution 图象消旋image degradation 星象劣化image dissector 析象管image distoration 星象复原image photon counting system 成象光子计数系统image sharpening 星象增锐image spread 星象扩散度imaging polarimetry 成象偏振测量imaging spectrophotometry 成象分光光度测量immersed echelle 浸渍阶梯光栅impulsive solar flare 脉冲太阳耀斑infralateral arc 外侧晕弧infrared CCD 红外CCDinfrared corona 红外冕infrared helioseismology 红外日震学infrared index 红外infrared observatory 红外天文台infrared spectroscopy 红外分光initial earth 初始地球initial mass distribution 初始质量分布initial planet 初始行星initial star 初始恒星initial sun 初始太阳inner coma 内彗发inner halo cluster 内晕族星团integrability 可积性Integral Sign galaxy ( UGC 3697 ) 积分号星系integrated diode array ( IDA ) 集成二极管阵intensified CCD 增强CCDIntercosmos 〈国际宇宙〉天文卫星interline transfer 行间转移intermediate parent body 中间母体intermediate polar 中介偏振星international atomic time 国际原子时International Celestial Reference 国际天球参考系Frame ( ICRF )intraday variation 快速变化intranetwork element 网内元intrinsic dispersion 内廪弥散度ion spot 离子斑IPCS, Image Photon Counting System 图象光子计数器IRIS, Infrared Imager / Spectrograph 红外成象器/摄谱仪IRPS, Infrared Photometer / Spectro- 红外光度计/分光计meterirregular cluster 不规则星团; 不规则星系团IRTF, NASA Infrared Telescope 〈IRTF〉美国宇航局红外Facility 望远镜IRTS, Infrared Telescope in Space 〈IRTS〉空间红外望远镜ISO, Infrared Space Observatory 〈ISO〉红外空间天文台isochrone method 等龄线法IUE, International Ultraviolet 〈IUE〉国际紫外探测器ExplorerJewel Box ( NGC 4755 ) 宝盒星团Jovian magnetosphere 木星磁层Jovian ring 木星环Jovian ringlet 木星细环Jovian seismology 木震学jovicentric orbit 木心轨道J-type star J 型星Juliet 天卫十一Jupiter-crossing asteroid 越木小行星Kalman filter 卡尔曼滤波器KAO, Kuiper Air-borne Observatory 〈柯伊伯〉机载望远镜Keck ⅠTelescope 凯克Ⅰ望远镜Keck ⅡTelescope 凯克Ⅱ望远镜Kuiper belt 柯伊伯带Kuiper-belt object 柯伊伯带天体Kuiper disk 柯伊伯盘LAMOST, Large Multi-Object Fibre 大型多天体分光望远镜Spectroscopic TelescopeLaplacian plane 拉普拉斯平面late cluster 晚型星系团LBT, Large Binocular Telescope 〈LBT〉大型双筒望远镜lead oxide vidicon 氧化铅光导摄象管Leo Triplet 狮子三重星系LEST, Large Earth-based Solar 〈LEST〉大型地基太阳望远镜Telescopelevel-Ⅰcivilization Ⅰ级文明level-Ⅱcivilization Ⅱ级文明level-Ⅲcivilization Ⅲ级文明Leverrier ring 勒威耶环Liapunov characteristic number 李雅普诺夫特征数( LCN )light crown 轻冕玻璃light echo 回光light-gathering aperture 聚光孔径light pollution 光污染light sensation 光感line image sensor 线成象敏感器line locking 线锁line-ratio method 谱线比法Liner, low ionization nuclear 低电离核区emission-line regionline spread function 线扩散函数LMT, Large Millimeter Telescope 〈LMT〉大型毫米波望远镜local galaxy 局域星系local inertial frame 局域惯性架local inertial system 局域惯性系local object 局域天体local star 局域恒星look-up table ( LUT ) 对照表low-mass X-ray binary 小质量X 射线双星low-metallicity cluster 低金属度星团;低金属度星系团low-resolution spectrograph 低分辨摄谱仪low-resolution spectroscopy 低分辨分光low - z 小红移luminosity mass 光度质量luminosity segregation 光度层化luminous blue variable 高光度蓝变星lunar atmosphere 月球大气lunar chiaroscuro 月相图Lunar Prospector 〈月球勘探者〉Ly-αforest 莱曼-α森林MACHO ( massive compact halo 晕族大质量致密天体object )Magellan 〈麦哲伦〉金星探测器Magellan Telescope 〈麦哲伦〉望远镜magnetic canopy 磁蓬magnetic cataclysmic variable 磁激变变星magnetic curve 磁变曲线magnetic obliquity 磁夹角magnetic period 磁变周期magnetic phase 磁变相位magnitude range 星等范围main asteroid belt 主小行星带main-belt asteroid 主带小行星main resonance 主共振main-sequence band 主序带Mars-crossing asteroid 越火小行星Mars Pathfinder 火星探路者mass loss rate 质量损失率mass segregation 质量层化Mayall Telescope 梅奥尔望远镜Mclntosh classification 麦金托什分类McMullan camera 麦克马伦电子照相机mean motion resonance 平均运动共振membership of cluster of galaxies 星系团成员membership of star cluster 星团成员merge 并合merger 并合星系; 并合恒星merging galaxy 并合星系merging star 并合恒星mesogranulation 中米粒组织mesogranule 中米粒metallicity 金属度metallicity gradient 金属度梯度metal-poor cluster 贫金属星团metal-rich cluster 富金属星团MGS, Mars Global Surveyor 火星环球勘测者micro-arcsec astrometry 微角秒天体测量microchannel electron multiplier 微通道电子倍增管microflare 微耀斑microgravitational lens 微引力透镜microgravitational lensing 微引力透镜效应microturbulent velocity 微湍速度millimeter-wave astronomy 毫米波天文millisecond pulsar 毫秒脉冲星minimum mass 质量下限minimum variance 最小方差mixed-polarity magnetic field 极性混合磁场MMT, Multiple-Mirror Telescope 多镜面望远镜moderate-resolution spectrograph 中分辨摄谱仪moderate-resolution spectroscopy 中分辨分光modified isochrone method 改进等龄线法molecular outflow 外向分子流molecular shock 分子激波monolithic-mirror telescope 单镜面望远镜moom 行星环卫星moon-crossing asteroid 越月小行星morphological astronomy 形态天文morphology segregation 形态层化MSSSO, Mount Stromlo and Siding 斯特朗洛山和赛丁泉天文台Spring Observatorymultichannel astrometric photometer 多通道天测光度计( MAP )multi-object spectroscopy 多天体分光multiple-arc method 复弧法multiple redshift 多重红移multiple system 多重星系multi-wavelength astronomy 多波段天文multi-wavelength astrophysics 多波段天体物理naked-eye variable star 肉眼变星naked T Tauri star 显露金牛T 型星narrow-line radio galaxy ( NLRG ) 窄线射电星系Nasmyth spectrograph 内氏焦点摄谱仪natural reference frame 自然参考架natural refenence system 自然参考系natural seeing 自然视宁度near-contact binary 接近相接双星near-earth asteroid 近地小行星near-earth asteroid belt 近地小行星带near-earth comet 近地彗星NEO, near-earth object 近地天体neon nova 氖新星Nepturian ring 海王星环neutrino astrophysics 中微子天文NNTT, National New Technology Telescope国立新技术望远镜NOAO, National Optical Astronomical 国立光学天文台Observatoriesnocturnal 夜间定时仪nodal precession 交点进动nodal regression 交点退行non-destroy readout ( NDRO ) 无破坏读出nonlinear infall mode 非线性下落模型nonlinear stability 非线性稳定性nonnucleated dwarf elliptical 无核矮椭圆星系nonnucleated dwarf galaxy 无核矮星系nonpotentiality 非势场性nonredundant masking 非过剩遮幅成象nonthermal radio halo 非热射电晕normal tail 正常彗尾North Galactic Cap 北银冠NOT, Nordic Optical Telescope 北欧光学望远镜nova rate 新星频数、新星出现率NTT, New Technology Telescope 新技术望远镜nucleated dwarf elliptical 有核矮椭圆星系nucleated dwarf galaxy 有核矮星系number density profile 数密度轮廓numbered asteroid 编号小行星oblique pulsator 斜脉动星observational cosmology 观测宇宙学observational dispersion 观测弥散度observational material 观测资料observing season 观测季occultation band 掩带O-Ne-Mg white dwarf 氧氖镁白矮星one-parameter method 单参数法on-line data handling 联机数据处理on-line filtering 联机滤波open cluster of galaxies 疏散星系团Ophelia 天卫七optical aperture-synthesis imaging 光波综合孔径成象optical arm 光学臂optical disk 光学盘optical light 可见光optical luminosity function 光学光度函数optically visible object 光学可见天体optical picture 光学图optical spectroscopy 光波分光orbital circularization 轨道圆化orbital eccentricity 轨道偏心率orbital evolution 轨道演化orbital frequency 轨道频率orbital inclination 轨道倾角orbit plane 轨道面order region 有序区organon parallacticon 星位尺Orion association 猎户星协orrery 太阳系仪orthogonal transformation 正交变换oscillation phase 振动相位outer asteroid belt 外小行星带outer-belt asteroid 外带小行星outer halo cluster 外晕族星团outside-eclipse variation 食外变光overshoot 超射OVV quasar, optically violently OVV 类星体variable quasar、optically violent variablequasaroxygen sequence 氧序pan 摇镜头parry arc 彩晕弧partial-eclipse solution 偏食解particle astrophysics 粒子天体物理path of annularity 环食带path of totality 全食带PDS, photo-digitizing system、PDS、数字图象仪、photometric data system 测光数据仪penetrative convection 贯穿对流pentaprism test 五棱镜检验percolation 渗流periapse 近质心点periapse distance 近质心距periapsis distance 近拱距perigalactic distance 近银心距perigalacticon 近银心点perimartian 近火点period gap 周期空隙period-luminosity-colour relation 周光色关系PG 1159 star PG 1159 恒星photoflo 去渍剂photographic spectroscopy 照相分光photometric accuracy 测光精度photometric error 测光误差photometric night 测光夜photometric standard star 测光标准星photospheric abundance 光球丰度photospheric activity 光球活动photospheric line 光球谱线planetary biology 行星生物学planetary geology 行星地质学Pleiad 昴团星plerion 类蟹遗迹plerionic remnant 类蟹遗迹plerionic supernova remnant 类蟹超新星遗迹plumbicon 氧化铅光导摄象管pluton 类冥行星p-mode p 模、压力模pointimg accuracy 指向精度point spread function 点扩散函数polarimetric standard star 偏振标准星polarization standard star 偏振标准星polar-ring galaxy 极环星系Portia 天卫十二post AGB star AGB 后恒星post-core-collapse cluster 核心坍缩后星团post-coronal region 冕外区post-main-sequence star 主序后星post red-supergiant 红超巨后星post starburst galaxy 星暴后星系post T Tauri star 金牛T 后星potassium-argon dating 钾氩计年precataclysmic binary 激变前双星precataclysmic variable 激变前变星preceding limb 西边缘、前导边缘precessing-disk model 进动盘模型precession globe 岁差仪precession period 进动周期preflash 预照光pre-main-sequence spectroscopic 主序前分光双星binarypre-planetary disk 前行星盘pre-white dwarf 白矮前身星primary crater 初级陨击坑primordial binary 原始双星principle of mediocrity 折衷原则progenitor 前身星; 前身天体progenitor star 前身星projected density profile 投影密度轮廓proper-motion membership 自行成员星proper reference frame 固有参考架proper reference system 固有参考系proplyd 原行星盘proto-binary 原双星proto-cluster 原星团proto-cluster of galaxies 原星系团proto-earth 原地球proto-galactic cloud 原星系云proto-galactic object 原星系天体proto-Galaxy 原银河系proto-globular cluster 原球状星团proto-Jupiter 原木星proto-planet 原行星proto-planetary disk 原行星盘proto-planetary system 原行星系proto-shell star 原气壳星proto-sun 原太阳pseudo body-fixed system 准地固坐标系Puck 天卫十五pulsar time scale 脉冲星时标pulsation axis 脉动对称轴pulsation equation 脉动方程pulsation frequency 脉动频率pulsation phase 脉动阶段pulsation pole 脉动极pulse light curve 脉冲光变曲线pyrometry 高温测量QPO, quasi-periodic oscillation 似周期振荡quantum cosmology 量子宇宙学quantum universe 量子宇宙quasar astronomy 类星体天文quiescence 宁静态radial pulsator 径向脉动星radial-velocity orbit 分光解radial-velocity reference star 视向速度参考星radial-velocity standard star 视向速度标准星radial-velocity survey 视向速度巡天radio arm 射电臂radio counterpart 射电对应体radio loud quasar 强射电类星体radio observation 射电观测radio picture 射电图radio pollution 射电污染radio supernova 射电超新星rapid burster 快暴源rapidly oscillating Ap star 快速振荡Ap 星readout 读出readout noise 读出噪声recycled pulsar 再生脉冲星reddened galaxy 红化星系reddened object 红化天体reddened quasar 红化类星体red horizontal branch ( RHB ) 红水平分支red nebulous object ( RNO ) 红色云状体Red Rectangle nebula 红矩形星云redshift survey 红移巡天red straggler 红离散星reflex motion 反映运动regression period 退行周期regular cluster 规则星团; 规则星系团relaxation effect 弛豫效应reset 清零resonance overlap theory 共振重叠理论return-beam tube 回束摄象管richness parameter 富度参数Ring nebula ( M 57、NGC 6720 ) 环状星云ring-plane crossing 环面穿越Rosalind 天卫十三ROSA T, Roentgensatellit 〈ROSAT〉天文卫星Rosette Molecular Cloud ( RMC ) 玫瑰分子云Rossby number 罗斯贝数rotating variable 自转变星rotational evolution 自转演化rotational inclination 自转轴倾角rotational modulation 自转调制rotational period 自转周期rotational phase 自转相位rotational pole 自转极rotational velocity 自转速度rotation frequency 自转频率rotation phase 自转相位rotation rate 自转速率rubber second 负闰秒rubidium-strontium dating 铷锶计年Sagittarius dwarf 人马矮星系Sagittarius dwarf galaxy 人马矮星系Sagittarius galaxy 人马星系Saha equation 沙哈方程Sakigake 〈先驱〉空间探测器Saturn-crossing asteroid 越土小行星Saturnian ringlet 土星细环Saturnshine 土星反照scroll 卷滚Sculptor group 玉夫星系群Sculptor Supercluster 玉夫超星系团Sculptor void 玉夫巨洞secondary crater 次级陨击坑secondary resonance 次共振secular evolution 长期演化secular resonance 长期共振seeing management 视宁度控管segregation 层化selenogony 月球起源学separatrice 分界sequential estimation 序贯估计sequential processing 序贯处理serendipitous X-ray source 偶遇X 射线源serendipitous γ-ray source 偶遇γ射线源Serrurier truss 赛路里桁架shell galaxy 壳星系shepherd satellite 牧羊犬卫星shock temperature 激波温度silicon target vidicon 硅靶光导摄象管single-arc method 单弧法SIRTF, Space Infrared Telescope 空间红外望远镜Facilityslitless spectroscopy 无缝分光slit spectroscopy 有缝分光slow pulsar 慢转脉冲星SMM, Solar Maximum MIssion 太阳极大使者SMT, Submillimeter Telescope 亚毫米波望远镜SOFIA, Stratospheric Observatory for 〈索菲雅〉机载红外望远镜Infrared Astronomysoft γ-ray burst repeater 软γ暴复现源soft γrepeater ( SGR ) 软γ射线复现源SOHO, Solar and Heliospheric 〈索贺〉太阳和太阳风层探测器Observatorysolar circle 太阳圈solar oscillation 太阳振荡solar pulsation 太阳脉动solar-radiation pressure 太阳辐射压solar-terrestrial environment 日地环境solitary 孤子性soliton star 孤子星South Galactic Cap 南银冠South Galactic Pole 南银极space density profile 空间密度轮廓space geodesy 空间大地测量space geodynamics 空间地球动力学Spacelab 空间实验室spatial mass segregation 空间质量分层speckle masking 斑点掩模speckle photometry 斑点测光speckle spectroscopy 斑点分光spectral comparator 比长仪spectrophotometric distance 分光光度距离spectrophotometric standard 分光光度标准星spectroscopic period 分光周期specular density 定向密度spherical dwarf 椭球矮星系spin evolution 自旋演化spin period 自旋周期spin phase 自旋相位spiral 旋涡星系spiral arm tracer 示臂天体Spoerer minimum 斯珀勒极小spotted star 富黑子恒星SST, Spectroscopic Survey Telescope 分光巡天望远镜standard radial-velocity star 视向速度标准星standard rotational-velocity star 自转速度标准星standard velocity star 视向速度标准星starburst 星暴starburst galaxy 星暴星系starburst nucleus 星暴star complex 恒星复合体star-formation activity 产星活动star-formation burst 产星暴star-formation efficiency ( SFE ) 产星效率star-formation rate 产星率star-formation region 产星区star-forming region 产星区starpatch 星斑static property 静态特性statistical orbit-determination 统计定轨理论theorysteep-spectrum radio quasar 陡谱射电类星体stellar environment 恒星环境stellar halo 恒星晕stellar jet 恒星喷流stellar speedometer 恒星视向速度仪stellar seismology 星震学Stokes polarimetry 斯托克斯偏振测量strange attractor 奇异吸引体strange star 奇异星sub-arcsec radio astronomy 亚角秒射电天文学Subaru Telescope 昴星望远镜subcluster 次团subclustering 次成团subdwarf B star B 型亚矮星subdwarf O star O 型亚矮星subgiant branch 亚巨星支submilliarcsecond optical astrometry 亚毫角秒光波天体测量submillimeter astronomy 亚毫米波天文submillimeter observatory 亚毫米波天文台submillimeter photometry 亚毫米波测光submillimeter space astronomy 亚毫米波空间天文submillimeter telescope 亚毫米波望远镜submillisecond optical pulsar 亚毫秒光学脉冲星submillisecond pulsar 亚毫秒脉冲星submillisecond radio pulsar 亚毫秒射电脉冲星substellar object 亚恒星天体subsynchronism 亚同步subsynchronous rotation 亚同步自转Sunflower galaxy ( M 63 ) 葵花星系sungrazer comet 掠日彗星supercluster 超星团; 超星系团supergalactic streamer 超星系流状结构supergiant molecular cloud ( SGMC ) 超巨分子云superhump 长驼峰superhumper 长驼峰星supermaximum 长极大supernova rate 超新星频数、超新星出现率supernova shock 超新星激波superoutburst 长爆发superwind galaxy 超级风星系supporting system 支承系统surface activity 表面活动surface-brightness profile 面亮度轮廓surface-channel CCD 表面型CCDSU Ursae Majoris star 大熊SU 型星SWAS, Submillimeter Wave Astronomy 亚毫米波天文卫星Satallitesymbiotic binary 共生双星symbiotic Mira 共生刍藁symbiotic nova 共生新星synthetic-aperture radar 综合孔径雷达systemic velocity 质心速度TAMS, terminal-age main sequence 终龄主序Taurus molecular cloud ( TMC ) 金牛分子云TDT, terrestrial dynamical time 地球力学时television guider 电视导星器television-type detector 电视型探测器Tenma 〈天马〉X 射线天文卫星terrestrial reference system 地球参考系tetrad 四元基thermal background 热背景辐射thermal background radiation 热背景辐射thermal pulse 热脉冲thermonuclear runaway 热核暴涨thick-disk population 厚盘族thinned CCD 薄型CCDthird light 第三光源time-signal station 时号台timing age 计时年龄tomograph 三维结构图toner 调色剂torquetum 赤基黄道仪TRACE, Transition Region and Coronal 〈TRACE〉太阳过渡区和日冕Explorer 探测器tracker 跟踪器transfer efficiency 转移效率transition region line 过渡区谱线trans-Nepturnian object 海外天体Trapezium cluster 猎户四边形星团triad 三元基tri-dimensional spectroscopy 三维分光triquetum 三角仪tuning-fork diagram 音叉图。

a r X i v :a s t r o -p h /0108459v 1 29 A u g 2001Luminosities and Space Densities of Short Gamma-Ray BurstsMaarten SchmidtCalifornia Institute of Technology,Pasadena,CA 91125mxs@ ABSTRACT Using the Euclidean value of <V/V max >as a cosmological distance indicator,we derive the isotropic-equivalent characteristic peak luminosity of gamma-ray bursts both longer and shorter than 2s.The short bursts have essentially the same characteristic peak luminosity of 0.6×1051erg (0.064s)−1as do the long bursts.This may apply also to bursts with durations less than 0.25s.The local space density of short bursts is around three times lower than that of long bursts.Subject headings:cosmology:observations —gamma rays:bursts 1.Introduction Since 1997,our understanding of gamma-ray bursts (GRB)has increased enormously through the optical identification of afterglows,determination of redshifts from optical spec-tra and generally from afterglow studies covering a large range of energies,from radio to X-rays.These studies suggest that GRBs are associated with massive stars and hence that the burst rate may be linked to the rate of star formation in galaxies.The number of GRBsso observed is still rather limited,and those successfully studied are all long bursts.We use the classification of GRBs in long bursts and short bursts based on the distribution of durations T 90in the BATSE data (Kouveliotou et al.1993),which show a minimum around 2s.No afterglows have been observed so far for short bursts (Gandolfiet al.2000).As a consequence,there is no direct knowledge of their redshifts,luminosities and space densities.There has been a suspicion that short GRBs would be at smaller redshifts and be of lower luminosities than long bursts,perhaps due to a remark in the abstract of a paper by Tavani (1998)that short bursts show little if any deviation from a Euclidean distribution but this is not supported by data discussed in the paper.In this Letter,we briefly discuss efforts to derive the luminosity function of long bursts and then present a derivation of the characteristic peak luminosity L∗and the local space density for both long and short bursts.Even though the total gamma-ray energy may be physically of greater interest(Frail et al.2001),we concentrate on peak luminosities since the detection of GRBs is based on count rates,not on the time-integratedflux orfluence of the burst.Before any redshifts of GRBs were known,Mao,Narayan,&Piran(1994)used the Euclidean value of<V/V max>as a relative distance indicator to show that long and short bursts had the same peak luminosity to within a factor of2,assuming they were standard candles.The redshifts that are now available for long bursts have led to the development of several luminosity indicators,such as the spectral lag derived from cross-correlation of two spectral channels(Norris,Marani&Bonnell2000)and the variability in the time profile (Fenimore&Ramirez-Ruiz2000).These luminosity indicators can in principle be used to derive the luminosity function of GRBs,including its evolution with redshift.Norris,Scargle &Bonnell(2001)have shown that the spectral lags for short bursts are much smaller than those of long bursts and conclude that the lag magnitude is discontinuous accross the2s valley between long and short bursts.We have used the Euclidean value of<V/V max>as a cosmological distance indicator tofirst derive characteristic luminosities(Schmidt1999b)and then the luminosity function of GRBs(Schmidt2001).This method,which makes use of a large sample of GRBs,cir-cumvents the current weakness of methods based on the small number of redshifts observed so far.The price we pay for using<V/V max>as a distance indicator is that an assumption has to be made about the evolution of the luminosity function with redshift.We assume that this evolution tracks the star formation rate(SFR)on the expectation that GRBs are associated with massive stars.We employ the parametrizations of Porciani&Madau(2001), in particular their SFR model SF2in which the co-moving space density rises by an order of magnitude near redshift z=1and then remains roughly constant for z>2(Steidel et al. 1999).Our application of<V/V max>as a distance indicator used the BD2sample(see Sec.2)which is based on BATSE DISCLA data on a time resolution of1024ms.The resulting characteristic luminosities(Schmidt1999b)and luminosity functions(Schmidt2001)there-fore applied to GRBs with a duration exceeding1or2s.In this Letter we employ the same method to derive characteristic luminosities L∗using the BATSE catalog.By using the GRBs detected with a time resolution of64ms,we can derive the L∗of short bursts. We will actually employ time resolutions of both64and1024ms,and obtain L∗for both short and long bursts,so that we can directly compare them.In Sec.2,we review the application of<V/V max>in deriving the luminosity function of long GRBs from the BD2sample without using redshifts and recall the main results obtained.Following a discussion of data from the BATSE catalog in Sec.3,we derive characteristic luminosities for both long and short GRBs in Sec.4.The results are discussed in Sec.5.Throughout this Letter,we use aflat cosmological model with H0=65km s−1 Mpc−1,ΩM=0.3,andΩΛ=0.7.2.Luminosity Function Of Long Bursts Derived From The BD2SampleThe BD2sample of GRBs is based on BATSE DISCLA data consisting of the continuous data stream from the eight BATSE LAD detectors in four energy channels on a timescale of 1024ms(Fishman et al.1989).The sample was derived using a software trigger algorithm requiring an excess of at least5σover background in at least two detectors in the energy range50−300keV.The initial version was described in Schmidt(1999a)and a revision in Sec. 2of Schmidt(1999b).The BD2sample covers a period of5.9yr from TJD8365−10528. It contains1391GRBs of which1013are listed in the BATSE catalog.The value of< V/V max>=0.336±0.008.The sample of1391GRBs effectively represents2.003yr of full sky coverage,corresponding to an annual rate of694GRBs.The derivation of the luminosity function of GRBs(Schmidt2001)was based on the correlation of the Euclidean value of<V/V max>with spectral hardness.Given that the Euclidean value of<V/V max>for a well defined sample of cosmological objects is a dis-tance indicator,we interpreted the correlation of<V/V max>with spectral hardness as a luminosity-hardness correlation.The luminosity function was derived as the sum of the lu-minosity functions of four spectral hardness classes.It can be characterized approximately as consisting of two power laws of slopes−0.6and−2,respectively,with an isotropic-equivalent break peak luminosity of log L∗∼51.5.The luminosity function ranges approximately from log L∗−1.5to log L∗+1.0.In the derivation of the characteristic luminosity L∗of GRBs from BATSE data in Sec. 4,we will assume that the shape and extent of the luminosity function is that of the broken power law just described and derive the value of log L∗from<V/V max>.This is essentially the method used in Schmidt(1999a),where we varied the assumed extent and shape of the luminosity function to study the effect on the derived value of log L∗.ing Data From The BATSE Catalog3.1.Evaluating V/V maxWe will be using<V/V max>values derived from the BATSE4B catalog1for bursts both longer and shorter than2s.Before we apply<V/V max>as a cosmological distance indicator,we consider how the individual V/V max values in the BATSE catalog are derived, and also how they are affected by the imposition of duration limits.The BATSE catalog lists for individual bursts the count rate in the second brightest illuminated detector,C max,as well as the minimum detectable rate C min.The value of V/V max is then simply derived as(C max/C min)−3/2.In contrast,the values of V/V max in the BD2sample have been derived through simulations,in which the burst is moved out in Euclidean space in small steps with a corresponding reduction in its amplitude.At each step,the full detection algorithm is re-employed to set the background and detect the burst. Once the burst is not detected any more,the value of V/V max is simply derived from the reduction factor.During this process of removal,the burst may get detected later and later depending on the time profile.The background time window,which precedes the detection by afixed time interval,may start to include some burst signal.Thefinal detection is usually made on the peak of the burst but in some cases where the burst signal preceding the peak is high and enters the background,thefinal detection may be offthe peak.Given that in these cases upon removal the burst drops out earlier than expected from C max/C min,the actual value of V/V max will be larger.In practice,the effect depends much on the time profile.The net effect for a sample of bursts is that(C max/C min)−3/2is an underestimate of<V/V max>.Next we consider the effect of imposing duration limits,such as T90<2s.In the simulations carried out on the BD2sample described above,we found that the duration of the burst decreased as it was moved out until at the limit of detection it was1or2s.A qualitatively similar effect has been described as afluence duration bias for GRBs in the BATSE catalog(Hakkila et al.2000).Suppose our sample is set by a restriction involving a limiting duration T lim.In deriving V/V max,we should strictly apply two simultaneous limits, namely C min and T lim,as was done in thefirst V/V max application(Schmidt1968).However, evaluating the effect of T lim on<V/V max>would require simulations of the derivation of T90for BATSE GRBs which are not available.Therefore,we limit ourselves tofinding the sign of the systematic error in<V/V max>if we ignore T lim.Consider the case of a GRB with a duration T90>T1.As we move the burst out,T90will decrease and may become smaller than T1before it becomes undetectable.Therefore the reduction factor is smaller and V/V max is larger.Ignoring the lower limit T1leads to an underestimate of V/V max.In the case of an upper limit T2,a GRB with T90>T2which does not belong to the sample,may become part of it when its T90becomes shorter than T2upon removal.In this case,ignoring the upper limit T2produces a V/V max that is an overestimate. It should be emphasized that these considerations are purely qualitative;the actual effects depend on such factors as the time profile of the burst,the way the background is set,etc.3.2.Effective CoverageIn order to derive the rate of GRBs per unit volume,we need to have an estimate of the effective full sky coverage of the GRB sample used.For the BD2we have evaluated the efficiency at33.8%leading to an effective full sky coverage of2.003yr(Schmidt1999a).The total sample of1391GRBs then corresponds to a rate of694GRB yr−1.The4B catalog gives an annual rate of666GRB yr−1,presumably based on the most sensitive detections,which are at the1024ms timescale.Considering that the S/N limit of the4B catalog is5.5σand that of the BD2sample5σ,these rates are quite consistent. We only consider GRBs detected while the BATSE on-board trigger was set for5.5σover the energy range50−300keV.Among those,the4B catalog contains612GRBs for which C max/C min≥1at the1024ms timescale(those<1were detected at time scales of64ms or256ms).This corresponds to an effective full sky coverage for the purpose of this work of0.92yr.We assume that this value also applies to the64ms timescale.4.Characteristic Luminosities For Long and Short BurstsThe method used to derive the isotropic-equivalent characteristic peak luminosity L∗for a given value of<V/V max>is essentially the same as that used before(Schmidt1999b). Based on our discussion of long bursts in Sec.2,the local luminosity function of peak GRB luminosities L,defined as the co-moving space density of GRBs in the interval log L to log L+d log L,isΦo(L)=0,for log L<log L∗−1.5,(1a)Φo(L)=c o(L/L∗)−0.6,for log L∗−1.5<log L<log L∗,(1b)Φo(L)=c o(L/L∗)−2.0,for log L∗<log L<log L∗+1.0,(1c)Φo(L)=0,for log L>log L∗+1.0.(1d)We assume that the GRB rate as a function of redshift follows the SFR model SF2(see Sec.1).The median value of the spectral photon index for the(long)bursts in the BD2 sample is−1.6(Schmidt2001).For the short bursts we adopt an index of−1.1to reflect their larger average hardness ratio(Kouveliotou et al.1993).The median4B limiting photonflux for1024ms detection in the50−300keV range, including the effect of atmospheric scattering,is0.25ph cm−2s−1(Meegan et al.1998).We adopt the same value for the BD2sample for which atmospheric scattering has not yet been evaluated.For GRBs detected on the64ms timescale,the derivation of L∗from<V/V max> is carried out on this timescale,so the resulting luminosity L∗is produced in ergs(0.064s)−1. In order to convert to this system from a timescale of1024ms,we compared for GRBs with T90>2s their peakfluxes at timescales1024ms and64ms given in the BATSE catalog. The average1024/64flux ratio is0.68,reflecting the variability of long GRBs at their peak at subsecond timescales.Accordingly,we convert peak luminosities per1024ms into ones per64ms by dividing by0.68×16=10.9.In order to provide a comparison with past work,wefirst derive L∗for long bursts. The top line of Table1shows the results for the BD2sample of GRBs.The value of L∗is70%larger than that found from the more sophisticated derivation in Schmidt(2001), which involved splitting the sample in groups of different spectral hardness.The resulting luminosity function was not exactly a broken power law,which causes the above difference.The remaining entries in Table1are all based on data from the4B catalog.Thefirst three can be directly compared with the BD2results since they all concern long bursts.The log L∗values show a range of0.3,with a systematic offset of around+0.2from the BD2 value.The local densities are systematically lower than that from the BD2,partly due to the higher luminosity.The next row of Table1gives the results for short bursts with T90<2s.The charac-teristic peak luminosity L∗is in the middle of the range given for long BATSE bursts.The local space density of short bursts is∼3times smaller than that of long bursts.In order to investigate whether there might be a trend among the short bursts,we show further results for T90<0.5s and<0.25s.The formal mean errors in log L∗for the short bursts are±0.20,±0.25,and±0.35,respectively.We see no trend of log L∗with duration among the short bursts.5.DiscussionThe systematic effect of using C max/C min in the derivation of<V/V max>discussed in Sec.3applies to all BATSE entries in Table1.Therefore all values of<V/V max>are systematically too small,and the resulting values of log L∗too large.The actual effect is hard to estimate because it depends on the burst profiles and the methodology of setting the background.For the BD2sample wefind that using C max/C min results in an underestimate of<V/V max>of0.009leading to an overestimate of log L∗by0.08.Considering this offset the agreement between thefirst two rows of Table1is satisfactory considering that the formal errors(derived from the mean errors of<V/V max>)in log L∗are±0.07and±0.10, respectively.For the BATSE bursts with T90>2s in the next two rows of Table1,the systematic effect caused by the duration limit may result in an overestimate of log L∗,but no obvious effect is evident.The short bursts with T90<2s have a value of log L∗that is entirely consistent with that of the long bursts.The systematic effect of the upper limit for the duration will be an underestimate of log L∗.This effect may well be small for short bursts,but only simulations can tell.The peak luminosities and local space densities given in Table1are isotropic-equivalent values and are all based on SFR model SF2(Sec.1).If,instead,we use SFR models SF1or SF3the derived values of log L∗typically change by−0.17and0.14,respectively,essentially the same for short and long bursts.Assuming that the BATSE values of log L∗are offset by+0.08,wefind that for our given assumptions about the shape and the evolution of the luminosity function,long bursts with T90>2s and short bursts with T90<2s have the same value of the characteristic peak luminosity L∗∼0.6×1051erg(0.064s)−1.As a consequence,short bursts will have lower radiated energies than long bursts,which may have a major effect on the afterglows of short GRBs(Panaitescu,Kumar,&Narayan2001).Among the short bursts there is no evidence for any substantial change in L∗for durations as short as0.25s.REFERENCESFenimore,E.E.,&Ramirez-Ruiz,E.2000,ApJ,submitted(astro-ph/0004176) Fishman,G.J.et al.1989,in GRO Science Workshop Proc.,ed.W.N.Johnson(Green-belt:NASA),2-39Frail,D.A.et al.2001,submitted(astro-ph/0102282)Gandolfi,G.et al.2000,in AIP Conf.Proc.526,Gamma-Ray Bursts,ed.R.M.Kippen,R.S.Mallozzi,&G.J.Fishman(New York:AIP),23Hakkila,J.,Meegan,C.A.,Pendleton,G.N.,Malozzi,R.S.,Haglin,D.J.&Roiger,R.J.2000,in AIP Conf.Proc.526,Gamma-Ray Bursts,ed.R.M.Kippen,R.S.Mallozzi, &G.J.Fishman(New York:AIP),48Kouveliotou,C.,Meegan,C.A.,Fishman,G.J.,Bhat,N.P.,Briggs,M.S.,Koshut,T.M., Paciesas,W.S.,&Pendleton,G.N.1993,ApJ,413,L101Mao,S.M.,Narayan,R.,&Piran,T.1994,ApJ,420,171Meegan,C.A.et al.1998,in AIP Conf.Proc.428,Gamma-Ray Bursts,ed.C.A.Meegan, R.D.Preece,&T.M.Koshut(New York:AIP),3Norris,J.P.,Marani,G.F.,&Bonnell,J.T.2000,ApJ,534,248Norris,J.P.,Scargle,J.D.,&Bonnell,J.T.2001,2nd Rome workshop,(astro-ph/0105108) Panaitescu,A.,Kumar,P.,&Narayan,R.2001,ApJ,submitted(astro-ph/0108132) Porciani,C.,&Madau,P.2001,ApJ,548,522Schmidt,M.,1968,ApJ,151,393Schmidt,M.,1999a,A&ASuppl,138,409Schmidt,M.,1999b,ApJ,523,L117Schmidt,M.,2001,ApJ,552,36Steidel,C.C.,et al.1999,ApJ,519,1Tavani,M.1998,ApJ,497,L21Table1.Characteristic Luminosity and Space Density From Various GRB Samples a.Sample∆t T90n<V/V max>αf lim b log L∗cρo da We use H0=65km s−1Mpc−1,ΩM=0.3,andΩΛ=0.7.b f lim is the limitingflux in ph cm−2s−1over the energy range50−300keV.c L∗is the isotropic-equivalent characteristic peak luminosity in erg(0.064s)−1in the50−300keV band.dρo is the local(z=0)GRB rate,in units of Gpc−3yr−1.。

e-mail:**************For latest product manuals: Shop online at User’s GuideTXDIN70 SERIESDual TransmitterThe information contained in this document is believed to be correct, but OMEGA accepts no liability for any errors it contains, andreserves the right to alter specifications without notice.Servicing North America:U.S.A.Omega Engineering, Inc.Headquarters:Toll-Free: 1-800-826-6342 (USA & Canada only)Customer Service: 1-800-622-2378 (USA & Canada only) Engineering Service: 1-800-872-9436 (USA & Canada only) Tel: (203) 359-1660 Fax: (203) 359-7700 e-mail:**************For Other Locations Visit /worldwide***********************MODEL COVEREDTXDIN70Description: Dual TransmitterSupply Power: 100~240VAC,50/60Hz TXDIN70-24V Description: Dual TransmitterSupply Power: 24VDCTXDIN70-DIS PLAY Description: Transmitter DisplaySupply Power: From TXDIN70 TransmitterTECHNICAL SPECIFICATIONInput type: Thermocouple K(-50 °C ~1,300 °C), S(-50 °C ~1,700 °C), R(-50 °C ~1,600 °C),E(0 °C ~1,000 °C), J(0 °C ~1,200 °C), N(-50 °C ~1,300 °C),T(-200 °C ~350 °C), B(0 °C ~1,800 °C),WRe5-WRe26(0 °C ~2,300 °C), WRe3-WRe25(°C 0~ 2,300 °C) RTD Cu50(-50 °C ~+150 °C), Pt100(-200 °C ~+900 °C)Linear Voltage0~1V, 0.2~1V, 0~20mV, 0~60mV, 0~100mVRetransmission accuracy:0.3%FS ± 1 digit (including input and output error)Output specification:Defined in the range of 0~22mAvoltage≥ 11VmaximumoutputwithTemperature drift:≤0.015%FS / °C (including the temperature drift of input and output) Electromagnetic compatibility (EMC):±4KV/5KHz according to IEC61000-4-4 (EFT);I EC61000-4-5to4KVaccordingIsolation withstanding voltage: Voltage between supply power andterminals≥300VDC;inputoutputsignalVoltage between inputs or 2 outputs ≥200VDCPower supply: 100~240VAC, -15%, +10% / 50~60Hz; or 24VDCPower consumption: ≤ 3WOperating Ambient :Temperature -10 °C~+60 °C; Humidity ≤90%RHRemark: Type-B thermocouple operates in the range of 60 °C ~400 °C but the measurement accuracy does not meet the stated accuracy. Accuracy is guranteed in the range of 400 °C~1,800 °C.CONNECTION DIAGRAMTerminal 1,2:Power supply of 100~240VAC (TXDIN70) orI N70-24V)(TXD24VDCTerminal 5,6 OP1:Positive and negative pole of channel 1retransmissionoutput.currentTerminal 7,8 OP2:Positive and negative pole of channel 2output.retransmissioncurrentTerminal 14,16 IN1: Channel 1 input.Terminal 10,12 IN2:Channel 2 input.OP1 and OP2 lights on when there is outputs in channel 1 and 2. Theluminosity change with the magnitude of output.MODE light blinks when transmitter is communicatiing with upper device.Blinking at 1.6 sec cycle: No active communication. Working normal without alarmBlinking at 0.6 sec cycle: No active communication with alarmBlinking at 0.3 sec cycle: No active communication with severe fault such as inputout of range.Light off: No power or out of order.Light kept on over 8 sec: Transmitter is powered on but it is out of orderDISPLA Y/OPERATIONParameters are set by an hot-plugged display TXDIN70-Display. Apart from nitial set-up, TXDIN70-Display can be stay connected serving as an external display.1 Upper Display: Displays PV of channel 1 or parametercode, When the display keeps flashing or the reading isabnormal, please check the input specification whether it iscorrectly set.2 Lower Display : Displays PV of channel 2 or parametervalue. When the display keeps flashing or the reading isabnormal, please check the input specification whether it iscorrectly set.3 Set Key: Accessing parameter table and to confirmparameter change.4 Data Point Shift (to the left)5 Data Decrease6 Data IncreaseRemark: The bundled IEEE-1394 cable is designed forcommunication between TXDIN70-Display and TXDIN70. Thiscable is not for other usages.Entering Parameter TableWhen the parameter lock “Loc” is not locked, press and hold for about 2 seconds to bring up the Full Parameter Table. Press (without holding) to bring up the parameters one by one. Press to modify a parameter value. Press to confirm and proceed to next one. Press and hold will return to the preceding parameter. Press and then by holding two keys will escape from the parameter table.When the parameter lock “Loc” is locked, press to bring up Field Parameter Table which show field parameters I NP1,I NP2, SCL1, SCL2, SCH1, SCH2. These field parameter value are not allowed to be changed due to the lock.The transmitter will automatically escape from the parameter table if there is no keys operation in 25 seconds. The change of the latest parameter will not be saved.TROUBLESHOOTINGWhen there is a fault, the upper display blinks out an error message.Error Message Description and SuggestionorAL Incorrect input specification paramter. Pleaes check the INP1 and/or INP2parameter.Thermocouple, RTD or analog input wiring is disconnected. Probe ofthermocouple or RTD is broken. Please check the wiring.Input wires are short-circuited. Please check the wiring.EErr IC Software error. Factory repair is required.8888IC Software error. Factory repair is required.PARAMETER TABLECode Parameter Description RangeINP1/ INP2 Input SpecificationDefine the input specification of channel 1~ 2.InP Input spec.InP Input spec.0K11~19Spare1S20Cu502R21Pt1003T22~24Spare4E250~75mV voltageinput5J26~27Spare6B280~20mV voltageinput7N290~100mV voltageinput8WRe3-WRe25300~60mV voltageinput9WRe5-WRe26310~1 V10Extended inputspecification 320.2~1V0~32SCL1/ SCL2 Scale Low Limit SCL and SCH define the corresponding scale range of linearoutput. For example, for channel 1, in order to retransmit0~600 °C to output channel 1, SCL1 should be set to 0,and SCH1 should be set to 600. For channel 2, to transmit0~1000°C, then SCL2=0, SCH2=1000.-999~+3000unitsSCH1/SCH2Scale High LimitScb1/ Scb2 Input Offset Scb is used to shift input to compensate the error caused bytransducer, input signal, or auto cold junction compensationof thermocouple.PV_after_compensation=PV_before_compensation + Scb-199~+999.0units/0.1 °CFIL1/FIL2Digital Filter The value of FIL will determine the ability of filtering noise.FIL=0, no filtering;FIL=1, filtering with mean;FIL=2~40, filtering with mean and integral.When a large value is set, the measurement input isstabilized but the response speed is slow. Generally, it canbe set to 1 to 3.If great interference exists, then you can increase parameterFIL gradually to make momentary fluctuation of measuredvalue less than 2 to 5.When the instrument is being metrological verified, FIL canbe set to 0 or 1 to shorten the response time.0~40OPn RetransmissionChannelAssignment OPn=1, For 1 input 1 output or 2 inputs 2 outputsretransmission application,OPn=2, For 1 input 2 outputs retransmission (Outputs frominput channel 2).0~2PARAMETER TABLE (cont.)Code Parameter Description RangeOPL Low Limitof CurrentRetransmissionof Channel 1Define the low limit and high limit of current retransmissionof channel 1. The engineering unit is 0.1mA.For example, to retransmit 0~600°C in input channel 1to 4~20mA, then the parameter should be set as below:SCL1=0, SCH1=600, OPn=1, OPL=40, OPH=200.0~110OPH High Limitof CurrentRetransmissionof Channel 10~220OPL2Low Limitof CurrentRetransmissionof Channel 2Define the low limit and high limit of currentretransmission of channel 2. The engineering unit is0.1mA.For example, to retransmit 0~1,000°C in input channel 2to 4~20mA, then the parameter should be set as below:SCL1=0, SCH1=1000, OPn=1, OPL=40, OPH=200.0~100OPH2High Limitof CurrentRetransmissionof Channel 20~220IVF1OP1 CurrentCorrection(Please recordthe value in thefirst use)For adjusting the current of OP1 output. The greater thevalue, the greater is the current output.Note: This parameter is calibrated in factory. It is not recommended to alter by user.0~3000/Default( )IVF2OP2 CurrentCorrection(Please recordthe value in thefirst use)For adjusting the current of OP2 output. The greater thevalue, the greater is the current output.Note: This parameter is calibrated in factory. It is not recommended to alter by user.0~3000/Default( )Loc Parameter Lock Loc=808: Allow to display and modify all parameters.Loc=any number: All parameters cannot be modified withonly INP1, INP2, SCL1, SCL2, SCH1 and SCH2 showing0~9999Where Do I Find Everything I Need for Process Measurement and Control?OMEGA…Of Course!Shop online at TEMPERATUREM U Thermocouple, RTD & Thermistor Probes, Connectors, Panels & AssembliesM U Wire: Thermocouple, RTD & ThermistorM U Calibrators & Ice Point ReferencesM U Recorders, Controllers & Process MonitorsM U Infrared PyrometersPRESSURE, STRAIN AND FORCEM U Transducers & Strain GagesM U Load Cells & Pressure GagesM U Displacement TransducersM U Instrumentation & AccessoriesFLOW/LEVELM U Rotameters, Gas Mass Flowmeters & Flow ComputersM U Air Velocity IndicatorsM U Turbine/Paddlewheel SystemsM U Totalizers & Batch ControllerspH/CONDUCTIVITYM U pH Electrodes, Testers & AccessoriesM U Benchtop/Laboratory MetersM U Controllers, Calibrators, Simulators & PumpsM U Industrial pH & Conductivity EquipmentDATA ACQUISITIONM U Communications-Based Acquisition SystemsM U Data Logging SystemsM U Wireless Sensors, Transmitters, & ReceiversM U Signal ConditionersM U Data Acquisition SoftwareHEATERSM U Heating CableM U Cartridge & Strip HeatersM U Immersion & Band HeatersM U Flexible HeatersM U Laboratory HeatersENVIRONMENTALMONITORING AND CONTROLM U Metering & Control InstrumentationM U RefractometersM U Pumps & TubingM U Air, Soil & Water MonitorsM U Industrial Water & Wastewater TreatmentM U pH, Conductivity & Dissolved Oxygen InstrumentsM4544/0617OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. 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Luminous efficacyFrom Wikipedia, the free encyclopediaJump to: navigation, searchLuminous efficacy is a figure of merit for light sources. It is the ratio of luminous flux(in lumens) to power(usually measured in watts). As most commonly used, it is the ratio of luminous flux emitted from a light source to the electric power consumed by the source, and thus describes how well the source provides visible light from a given amount of electricity.[1] This is also referred to as luminous efficacy of a source.The term luminous efficacy can also refer to luminous efficacy of radiation (LER), which is the ratio of emitted luminous flux to radiant flux. Luminous efficacy of radiation is a characteristic of a given spectrum that describes how sensitive the human eye is to the mix of wavelengths involved. Which sense of the term is intended must usually be inferred from the context, and is sometimes unclear. The luminous efficacy of a source is the LER of its emission spectrum times the conversion efficiency from electrical energy to electromagnetic radiation.[1]Contents[hide]• 1 Efficacy and efficiency• 2 Luminous efficacy of radiationo 2.1 Explanationo 2.2 Mathematical definitiono 2.3 Examples• 3 Lighting efficiencyo 3.1 Examples• 4 SI photometry units• 5 See also• 6 References•7 External links[edit] Efficacy and efficiencyIn some other systems of units, luminous flux has the same units as radiant flux. The luminous efficacy of radiation is then dimensionless. In this case, it is often instead called the luminous efficiency or luminous coefficient and may be expressed as a percentage. A common choice is to choose units such that the maximum possible efficacy, 683 lm/W, corresponds to an efficiency of 100%. The distinction between efficacy and efficiency is not always carefully maintained in published sources, so it is not uncommon to see "efficiencies" expressed in lumens per watt, or "efficacies" expressed as a percentage.[edit] Luminous efficacy of radiation[edit] ExplanationThe response of a typical human eye to light, as standardized by the CIE in 1924. The horizontal axis is wavelength in nmWavelengths of light outside of the visible spectrum are not useful for illumination because they cannot be seen by the human eye. Furthermore, the eye responds more to some wavelengths of light than others, even within the visible spectrum. This response of the eye is represented by the luminosity function. This is a standardized function which represents the response of a "typical" eye under bright conditions (Photopic vision). One can also define a similar curve for dim conditions (Scotopic vision). When neither is specified, photopic conditions are generally assumed.Luminous efficacy of radiation measures the fraction of electromagnetic power which is useful for lighting. It is obtained by dividing the luminous flux by the radiant flux. Light with wavelengths outside the visible spectrum reduces LER, because it contributes to the radiant flux while the luminous flux of such light is zero. Wavelengths near the peak of the eye's response contribute more strongly than those near the edges.In SI, luminous efficacy has units of lumens per watt (lm/W). Photopic luminous efficacy of radiation has a maximum possible value of 683 lm/W, for the case of monochromatic light at a wavelength of 555 nm (green). Scotopic luminous efficacy of radiation reaches a maximum of 1700 lm/W for narrowband light of wavelength 507 nm.[edit] Mathematical definitionThe dimensionless luminous efficiency measures the integrated fraction of the radiant power that contributes to its luminous properties as evaluated by means of the standard luminosity function.[2] The luminous coefficient iswhereyis the standard luminosity function,λJis the spectral power distribution of the radiant intensity.λThe luminous coefficient is unity for a narrow band of wavelengths at 555 nanometres.Note that is an inner product between yλand Jλand that is the one-norm of Jλ.[edit] ExamplesSpectral radiance of a black body. Energy outside the visible wavelength range (~380–750 nm, shown by grey dotted lines) reduces the luminous efficiency.[edit] Lighting efficiencyArtificial light sources are usually evaluated in terms luminous efficacy of a source, also sometimes called overall luminous efficacy. This is the ratio between the total luminous flux emitted by a device and the total amount of input power (electrical, etc.) it consumes. It is also sometimes referred to as the wall-plug luminous efficacy or simply wall-plug efficacy. The overall luminous efficacy is a measure of the efficiency of the device with the output adjusted to account for the spectral response curve (the “luminosity function”). When expressed in dimensionless form (for example, as a fraction of the maximum possible luminous efficacy), this value may be called overall luminous efficiency, wall-plug luminous efficiency, or simply the lighting efficiency.The main difference between the luminous efficacy of radiation and the luminous efficacy of a source is that the latter accounts for input energy that is lost as heat or otherwise exits the source as something other than electromagnetic radiation. Luminous efficacy of radiation is a property of the radiation emitted by a source. Luminous efficacy of a source is a property of the source as a whole.[edit] ExamplesThe following table lists luminous efficacy of a source and efficiency for various light sources:Sources that depend on thermal emission from a solid filament, such as incandescent light bulbs, tend to have low overall efficacy compared to an ideal blackbody source because, as explained by Donald L. Klipstein, “An ideal thermal radiator produces visible light most efficiently at temperatures around 6300 °C (6600K or 11,500 °F). Even at this high temperature, a lot of the radiation is either infrared or ultraviolet, and the theoretical luminous [efficacy] is 95 lumens per watt. Of course, nothing known to any humans is solid and usable as a light bulb filament at temperatures anywhere close to this. The surface of the sun is not quite that hot.”[13]At temperatures where the tungsten filament of an ordinary light bulb remains solid (below 3683 kelvins), most of its emission is in the infrared.[13][edit] SI photometry unitsSI photometry unitsv•d•e[edit] See also•Luminous coefficient•Photometry•Light pollution•Wall-plug efficiency- a related principle, but slightly different [edit] References1.^ a b Ohno, Yoshi (2004), "Color Rendering and Luminous Efficacy of WhiteLED Spectra", Proc. of SPIE (Fourth International Conference on Solid State Lighting), 5530, SPIE, Bellingham, WA, pp. 88,doi:10.1117/12.565757,/Divisions/Div844/facilities/photo/Publications/OhnoSPIE2004.pdf2.^Van Nostrand's Scientific Encyclopedia, 3rd Edition. Princeton, NewJersey, Toronto, London, New York: D. Van Nostrand Company, Inc.. January 1958.3.^ a b Defined such that the maximum value possible is 100%.4.^ a b Black body visible spectrum5.^ a b See luminosity function.6.^ 1 candela*4πsteradians/40 W7.^Westermaier, F. V. (1920). "Recent Developments in Gas Street Lighting".The American City (New York: Civic Press) 22 (5): 490./books?id=rWxLAAAAMAAJ&dq=mantle%20lamp&pg=PA 490#v=onepage&q=mantle%20lamp&f=false.8.^Bulbs: Gluehbirne.ch: Philips Standard Lamps (German)9.^ a b c d e f Philips Product Catalog (German)10.^ "Osram halogen" (in German) (PDF). www.osram.de.http://www.osram.de/_global/pdf/osram_de/tools_services/downloads/al lgemeinbeleuchtung/halogenlampen/haloluxhalopar.pdf. Retrieved2008-01-28.[dead link]11.^ a b Keefe, T.J. (2007). "The Nature of Light"./physics/keefe/light.htm. Retrieved 2007-11-05. 12.^ "Osram Miniwatt-Halogen". ./tsshop/WGS/411/PRD/LFH0324408/Osram_6406330_ 500mA_52V_E10_BLK1_MINIWATT-Halogen-Gluehlampe_f.Taschenl..htm.Retrieved 2008-01-28.[dead link]13.^ a b c Klipstein, Donald L. (1996). "The Great Internet Light Bulb Book,Part I". /tom.baldwin/bulbguide.html.Retrieved 2006-04-16.14.^ "Nichia NSPWR70CSS-K1 specifications" (pdf). Nichia Corp..http://www.nichia.co.jp/specification/led_09/NSPWR70CSS-K1-E.pdf.Retrieved April 26, 2009.15.^Klipstein, Donald L.. "The Brightest and Most Efficient LEDs and whereto get them". Don Klipstein's Web Site./don/led.html#ln. Retrieved 2008-01-15.16.^ "Cree launches the new XLamp 7090 XR-E Series Power LED, the first160-lumen LED!". /products/xlamp_new.asp.17.^"Luxeon K2 with TFFC; Technical Datasheet DS60" (PDF). PhilipsLumileds./pdfs/DS60.pdf. Retrieved 2008-04-23.18.^ a b "Technical Information on Lamps" (pdf). Optical Building Blocks./UVvis/TechNotes/TechnicalInformationLamps.pdf.Retrieved 2007-10-14. Note that the figure of 150 lm/W given for xenon lamps appears to be a typo. The page contains other useful information.19.^OSRAM Sylvania Lamp and Ballast Catalog. 2007.20.^ "Low Mercury CFLs". Energy Federation Incorporated./consumer/default.php/cPath/25_44_3006. Retrieved 2008-12-23.21.^ "Conventional CFLs". Energy Federation Incorporated./consumer/default.php/cPath/25_44_784.Retrieved 2008-12-23.22.^ a b Federal Energy Management Program (December 2000). How to buy anenergy-efficient fluorescent tube lamp. U.S. Department of Energy./femp/procurement/eep_fluortube_lamp.html .23.^Department of the Environment, Water, Heritage and the Arts, Australia."Energy Labelling—Lamps"..au/appsearch/download.asp. Retrieved 2008-08-14.24.^"1000-watt sulfur lamp now ready". IAEEL newsletter(IAEEL) (1). 1996.Archived from the original on Aug. 18, 2003./web/20030818061414/195.178.164.205/IAEEL/iaeel/newsl/1996/ett1996/LiTech_b_1_96.html.25.^ "The Metal Halide Advantage". Venture Lighting. 2007./TechCenter/Metal-Halide-TechIntro.html. Retrieved 2008-08-10.26.^ a b "LED or Neon? A scientific comparison"./index.php/channel/12/id/138/.27.^ "Why is lightning coloured? (gas excitations)"./causesofcolor/4.html.[edit] External links•Hyperphysics has these graphs of efficacy that do not quite comply with the standard definition•Energy Efficient Light Bulbs•Other Power•CIPCO Energy LibraryRetrieved from "/wiki/Luminous_efficacy" Categories: Photometry | Physical quantities | Lighting | Energy economicsHidden categories: All articles with dead external links| Articles with dead external links from June 2008 | All articles with unsourced statements | Articles with unsourced statements from March 2009（注：可编辑下载，若有不当之处，请指正，谢谢!）。

a rXiv:as tr o-ph/9811399v223Jan1999LYMAN BREAK GALAXIES AT Z >∼4AND THE EVOLUTION OF THE UV LUMINOSITY DENSITY AT HIGH REDSHIFT 1Charles C.Steidel 2and Kurt L.Adelberger Palomar Observatory,Caltech 105–24,Pasadena,CA 91125Mauro Giavalisco and Mark Dickinson Space Telescope Science Institute,3700San Martin Drive,Baltimore,MD 21218Max Pettini Royal Greenwich Observatory,Madingley Road,Cambridge CB30EZ,UK ABSTRACT We present initial results of a survey for star-forming galaxies in the redshift range 3.8<∼z <∼4.5.This sample consists of a photometric catalog of 244galaxies culled from a total solid angle of 0.23square degrees to an apparent magnitude of I AB =25.0.Spectroscopic redshifts in the range 3.61≤z ≤4.81have been obtained for 48of these galaxies;their median redshift is z =4.13.Selecting these galaxies in a manner entirely analogous to our large survey for Lyman break galaxies at smaller redshift (2.7<∼z <∼3.4)allows a relatively clean differential comparison between the populations and integrated luminosity density at these two cosmic epochs.Over the same range of UV luminosity,the spectroscopic properties of the galaxy samples at z ∼4and z ∼3are indistinguishable,as are the luminosity function shapes and the total integrated UV luminosity densities (ρUV (z =3)/ρUV (z =4)=1.1±0.3).We see no evidence at these bright magnitudes for the steep decline in the star formation density inferred from fainter photometric Lyman-break galaxies in the Hubble Deep Field (HDF).The HDF provides the only existing data on Lyman-break galaxy number densities at fainter magnitudes.We have reanalyzed the z ∼3and z ∼4Lyman-break galaxies in the HDF using our improved knowledge of the spectral energy distributions of these galaxies,and we find,like previous authors,that faint Lyman-break galaxies appear to be rarer at z ∼4than z ∼3.This might signal a large change in the faint-end slope of the Lyman-break galaxy luminosity function between redshifts z ∼3and z ∼4,or,more likely,be due to significant variance in the number counts within the small voluesprobed by the HDF at high redshifts(∼160times smaller than the ground–basedsurveys discussed here).If the true luminosity density at z∼4is somewhat higherthan implied by the HDF,as our ground-based sample suggests,then the emissivity ofstar formation as a function of redshift would appear essentially constant for all z>1once internally consistent corrections for dust are made.This suggests that there maybe no obvious peak in star formation activity,and that the onset of substantial starformation in galaxies might occur at z>∼4.5.Subject headings:galaxies:evolution—galaxies:formation—galaxies:distances andredshifts—large scale structure of the universe1.INTRODUCTIONWithin the last few years it has become possible to undertake large surveys of galaxies at very large redshifts(z>2).Simple photometric techniques keyed to the passage of the Lyman break through broad-bandfilters allow efficient selection of high redshift galaxy candidates (Steidel,Pettini&Hamilton1995;Steidel et al.1996a,b;Madau et al.1996)which can then be confirmed and studied thanks to the large spectroscopic throughput of the Low Resolution Imaging Spectrograph on the W.M.Keck10m telescopes(Oke et al.1995).It is now feasible to study the large-scale distribution of star-forming galaxies at high redshift(Steidel et al.1998;Giavalisco et al.1998;Adelberger et al.1998),and to obtain large enough samples of galaxies that accurate luminosity functions,color distributions,and the like for z∼3objects can be compiled(e.g., Dickinson1998;Steidel et al.1998b).The advantage of large and reasonably well defined samples is that they allow direct comparisons to the predictions of galaxy and structure formation models (e.g.,Baugh et al.1998;Governato et al.1998;Katz,Hernquist,&Weinberg1998;Wechsler et al.1998;Somerville,Primack,&Faber1998;Coles et al.1998;Bagla1998;Jing&Suto1998).Most of the work up to the present has concentrated on the redshift regime2.5<∼z<∼3.5,for primarily practical reasons.These are the lowest redshifts at which the so-called“Lyman-break”technique can be applied using ground-based photometry.Also,at z∼3the spectroscopic features that are most useful for determining the redshifts of Lyman-break galaxies(LBGs)fall within the wavelength range for which optical spectrographs are most efficient,and in which the night sky background is minimal.As discussed by Steidel et al.1998b,while conceptually it is straightforward to extend the Lyman-break technique to higher redshift(one simply uses afilter system that is shifted to longer wavelengths),the spectroscopic confirmation of photometrically selected objects becomes far more difficult.The Lyman-break technique has already been used in a very powerful way in the Hubble Deep Field to estimate the star formation history of the Universe in coarse redshift bins defined by galaxies’Lyman breaks passing through the F300W,F450W,and F606Wfilters(Madau etal.1996;Madau,Pozzetti,&Dickinson1998,hereafter MPD).It has now become a major industry to place any observation of high redshift objects in the context of their implied contribution to the history of star formation,using the Hubble Deep Field(HDF)observations as the basis for comparison at high redshifts(z>∼2).Possibly one of the most important results from a series of papers by Madau and others is the large apparent increase in ultraviolet luminosity density between redshift bins centered at z ≈4and z ≈2.75,which suggests a rapid increase in the co-moving volume-averaged rate of star formation over a rather short interval of cosmic time. This intriguing result appears to be consistent with what is observed for the space density of luminous,high redshift QSOs(e.g.Schmidt et al.1995,Kennefick et al.1995,Shaver et al.1998), and implies that at z>∼4one is entering the“dark ages,”the epoch when star formation wasfirst turning on in galaxies.Some other studies using photometric redshifts in the HDF,however,did notfind evidence for such a clear change in the UV luminosity density over this redshift range (e.g.Sawicki et al.1997;Pascarelle et al.1999).There are several reasons to be concerned about results based solely on the Hubble Deep Field,however.First,the HDF,while clearly the highest quality image of the sky ever obtained, is after all only a very small piece of sky(≃5arcmin2),and samples a relatively small volume at any redshift.Since observations of the Lyman-break galaxies at z∼3in ground-based surveys have shown that high redshift(luminous)star-forming galaxies are strongly clustered(Steidel et al.1998a,Giavalisco et al.1998,Adelberger et al.1998),one might be concerned about sample variance associated with a relatively small volume.Moreover,even if the HDF provided a fair sample of the universe,the redshift distributions of F300W and F450W dropouts are not well known empirically.As a result,the effective volumes used by Madau et al.to calculate the star-formation densities at z =2.75and z =4were based upon models of the spectral-energy distributions and Lyman-continuum opacities of galaxies,and not on spectroscopic redshifts.We have found,in our large survey at z∼3,that the effective redshift selection function imposed by a particular set of photometric selection criteria is not a simple“boxcar”as assumed by Madau et al.Objects near the assumed boundaries of the N(z)function are under–represented dueto photometric errors,and,more importantly,to the fact that there are substantial variationsin the spectra of galaxies at a given redshift.These variations are due,among other things,to the stochastic nature of the line blanketing in the Lymanαforest,to the amount of intrinsic reddening by dust,and to whether Lymanαis in emission or absorption.While such subtleties may not seem important for the rather crude luminosity densities estimated from photometric redshifts,they undoubtedly have at least some effect on the implied luminosity densities,and the magnitude of this effect is difficult to estimate without spectroscopic redshifts.In view of the importance of confirming the decline in the far-UV luminosity density between z∼3and z∼4,and the fact that we now have a substantial sample of galaxies in the redshift range2.6<∼z<∼3.4from our relatively wide-angle ground-based surveys,we have undertakento compile wide-field photometry and spectroscopic confirmation of Lyman-break galaxies in a redshift interval3.8<∼z<∼4.5.Although comparatively low spatial resolution and significantly brighter backgrounds make it difficult to reach the depth of the HDF from the ground,it is feasible to to survey much larger fields;our present survey aims to exploit this advantage.We have attempted to reach depths for z∼4LBGs that are comparable to our existing survey at z∼3,over a region∼160times larger than the HDF.The z∼3survey has been based entirely on the custom U n G Rfilter system(described in detail in Steidel&Hamilton1993),with effective wavelengths of3650,4750, and6930˚A,respectively.It turns out to be remarkably efficient,for the purposes of selecting Lyman-break galaxies at z>∼4,to add one passband(I,with an effective wavelength of8100˚A) to our existing imaging data,and to select G-band dropouts using the G R I system in a manner entirely analogous to the way we have used U n G R at z∼3.In this paper,we present the initial results of our galaxy survey with an expected median redshift of z =4.2,to demonstrate the feasibility of extending spectroscopic Lyman-break galaxy surveys to higher redshifts,and to make a preliminary estimate of the star formation luminosity density for comparison to the analogous value at z∼3,all based on data that are independent of the Hubble Deep Field.2.PHOTOMETRIC SELECTION CRITERIAThe photometric selection criteria,as for our z∼3sample,are based upon a combination of the expectations from modeling the spectral energy distributions of star-forming objects at high redshift,combined with practical considerations such as allowing for photometric errors,and steering away from regions in the G R I color–color plane that are obviously contaminated with objects that are not at very high redshift(i.e.,“interlopers”).Our intention initially was to err on the side of caution and obtain redshifts for objects with a rather broad range of colors,since we did not know a priori where in the G R I color–color plane the population of z∼4objects would lie.We defined the initial color selection criteria with the observed range of intrinsic z∼3galaxy colors in mind.As will be discussed elsewhere(Adelberger et al.1999),the colors of the galaxies in our z∼3sample are consistent with standard Bruzual and Charlot(1996)models of continuous star formation,altered by the statistical opacity of the IGM(following Madau1995)and a component of optically thick H I in the galaxy itself3,and reddened by applying a version of the starburst galaxy obscuration relation of Calzetti(1997)extrapolated to wavelengths shorter than 1200˚A4The range of UV colors observed in the z∼3sample is well represented by such modelswith E(B−V)ranging from zero to∼0.3magnitudes,with a median color(which can be thought of as the spectrum of the“typical”Lyman-break galaxy in the z∼3sample)corresponding to E(B−V)=0.15for the adopted reddening curve(note that this corresponds to an extinction at rest-frame∼1700˚A[the observed R band]of about a factor of4).All magnitudes and colors used in this paper are reported on the“AB”system(Oke&Gunn1983).Our G R I photometric selection criteria were designed to select galaxies at z∼4with a range of intrinsic SEDs similar to what is observed in our U n G R sample at z∼3.In Figure1a,we have plotted the tracks in the G R I color–color plane for the model spectra which closely match the observed galaxies at z∼3;the same model galaxies are plotted in Figure1b to show their location relative to the color selection window used for the z∼3sample.There are two different color selection windows indicated in Figure1a.The shaded region is the one actually used to select objects for spectroscopic follow-up,which was intended to be relatively broad in order to explore the color–color space(and the effects of photometric scatter)somewhat;the bold line encompasses the region which we will use as our primary selection window for comparison with the z∼3data. The latter was adopted because it would result in comparable effective volumes near z =4.2and z =3.05in our two surveys if galaxies had the same range of intrinsic colors at these redshifts, and also because(as we shall see below)it turns out that one can eliminate a substantial fraction of the interlopers by keeping the R−I colors relatively blue.This selection window is defined by G−R≥2.0,G−R≥2(R−I)+1.5,R−I≤0.6.The“median color”galaxy model(the middle of the three color-color tracks shown in Figure 1a)enters the primary selection window at z∼3.9,and exits again at z∼4.5,so that this would be the a priori expected redshift range of a galaxy sample similar to the one observed at z∼3.Thisfigure also shows that bluer(i.e.,less reddened)galaxies are expected to be biased somewhat toward the higher redshifts,and redder(i.e.,more reddened)ones toward the lower redshifts;this is the main effect that makes the realized N(z)function different from a“boxcar”(see,e.g.,Steidel et al.1998b,and Figure4).In Figure1a we have also plotted the color tracks for a template elliptical galaxy,with only k-corrections applied(i.e.,no spectral evolution).Note that the locus of unevolved early type galaxies comes very close to the selection window for the z∼4galaxies for z∼0.5−1.A combination of photometric errors and intrinsic variations in galaxy spectral-energy distributions can scatter some early-type galaxies at these redshifts into our selection window.It turns out that such objects are the sole source of“interlopers”for the z>∼4sample,and we suggest below ways that their contribution can be minimized.Note also that no contamination by stars is expected(unlike in the z∼3sample—see Figure1b).3.OBSER V ATIONS3.1.ImagingWith the exception of DSF1550,all of thefields included here have been part of our extensive survey for z∼3galaxies;thefield centers are given in Table1.The imaging data were obtained at the William Herschel telescope(3C324and B20902+34),Palomar200-inch Hale telescope (CDFa,CDFb,DSF2237a,DSF2237b,SSA22a,SSA22b,and B20902+34),and the CTIO4m telescope(DSF1550+08)during the interval1996-98.All of the imaging data and the photometric methods employed will be presented in detail elsewhere;in brief,the photometry was performed in a manner identical to that used for the z∼3galaxy searches,which is described(for example) in Steidel,Pettini,&Hamilton(1995),with the exception that we have used a modified version of the FOCAS(Valdes1982)image detection and analysis routines that one of us(KLA)has optimized for our purposes.Forfields in which existing U n G R catalogs were already on hand,we simply registered the I image onto the same coordinate system and obtained the I magnitudes and R−I colors through the same matched apertures.We have performed our object detection on the R band images because they are in most cases significantly deeper than in the I band.However,the selection of candidate z∼4galaxies has been made using the I band total magnitudes.(This procedure is unlikely to present any significant biases,given that the expected colors are quite blue in R−I, and our R images typically reach∼0.5magnitudes deeper than the I images).The typical depths of our images,in∼1′′seeing,are29.3,28.5,and28.0magnitudes per square arc second for G, R,and I,respectively,within a1′′aperture(1σ).Thus,an object with I=25is approximately a5−10σdetection in the I band,with considerable dynamic range available to measure colors in the G and R bands.We have chosen to limit the object catalogs to I≤25.0in order to provide a relatively high level of photometric completeness and ensure that there would be sufficient dynamic range to detect breaks in the G−R colors.We will discuss completeness issues in§4below.The photometric selection criteria summarized in Figure1a(shaded region)were used to isolate candidates for z>∼4objects.All such candidates were examined visually in order to remove objects that were clearly spurious(these usually were found near very bright stars).A summary of the number of remaining candidates in eachfield is given in Table1.A composite2-color diagram from the10fields included in this paper is shown in Figure2.3.2.SpectroscopyAll of the galaxy spectra were obtained using the Low Resolution Imaging Spectrograph (Oke et al.1995)on the Keck II10m telescope,between1997March and1998October.For the observing runs in1997,we generally included several slits targeting z∼4candidates on masks designed primarily for our z∼3LBG survey;as a consequence,most of these spectrawere obtained using the300line/mm grating blazed at5000˚A and with a grating tilt optimized for the4000–7000˚A range.A more efficient configuration,with better sensitivity in the crucial 6000-7500˚A range,was to use a150line/mm grating blazed at7500˚A;this was used in the1998 observing runs and increased the spectroscopic success rate by about a factor of2–3for both z∼4 galaxies and lower redshift interlopers(e.g.,a single slit mask,with16candidate objects,yielded 7successful redshifts in the3.9≤z≤4.5and one z=0.96interloper in the DSF1550field in 1998May—the remaining8candidates had inadequate S/N for identification).Slit widths on the masks were either1′′.0or1′′.4,resulting in spectral resolution ranging from10-12˚A for the300line configuration and20-25˚A for the150line configuration.Typical total exposure times per mask were2hours,usually broken into individual exposures of1200or1800s,with small dithers along the slitlets between exposures in order to sample different parts of the detector and to allow the option of various schemes for the removal of fringes at redder wavelengths.The data were reduced using a suite of custom IRAF scripts.Examples of z∼4galaxy spectra are shown in Figure3.The onset of strong Lymanαforest blanketing is very apparent in the spectra of these galaxies.As in the z∼3sample,there is a wide variety of spectroscopic properties,ranging from Lymanαin emission with rest-frame equivalent widths up to∼80˚A,to objects with very strong Lymanαabsorption and accompanying strong lines of various interstellar transitions of low ions,to objects that have Lymanαin both absorption and in emission(see,e.g.,the spectrum of HDF G4in Figure3).There is an obvious spectroscopic bias against objects that do not have strong emission lines,but even with this bias about half of our successful redshifts are based purely on absorption features.The substantial fraction of absorption-dominated spectra in our z∼4sample may be due in part to the large intrinsic luminosities of the galaxies;we see some evidence in our z∼3sample,which reaches fainter intrinsic luminosities,that brighter objects tend to have absorption-dominated spectra. These effects will will be quantified elsewhere.Unsuccessful redshifts were invariably due to lack of adequate S/N.This is a more serious problem at z∼4than at z∼3,largely because the spectral features used to identify redshifts are moved from4500–6000˚A to6500–7500˚A,where the sky is1.5–2magnitudes brighter.As a result our success rate for identifying redshifts is∼30–50%at z∼4,compared to>∼80%at z∼3. Objects with strong Lymanαemission lines are clearly less likely to fall into the“unsuccessful”category,as the continuum S/N is much less important than for the absorption line objects,and for this reason it is likely that most of the spectra which remain to be identified do not have Lymanαemission with large equivalent width.In the range of continuum luminosity that we are currently probing,even very sensitive narrow-band searches would turn up only a relatively small fraction of the galaxies(cf.Hu et al.1998).The magnitudes,colors,and redshifts of all48of the spectroscopically confirmed z>∼4 galaxies are summarized in Table2.Also summarized are the same quantities for the galaxies identified as interlopers;all73of the objects with redshifts are indicated with shaded“dots”on Figure2.From Figure2,it is clear that most of the objects in the selection window with redR−I colors are interlopers.As mentioned above,by tightening the color selection window to include only objects having R−I≤0.6,one immediately eliminates11of the25interlopers,most of which have z∼1,as expected from Figure1a;only2out of48of the bonafide high redshift galaxies are excluded5.In addition,applying the requirement that the galaxies must have I≥23.0 (this will tend to screen out z∼0.5early type galaxies,which will typically have I∼21−22) eliminates an additional2interlopers in the spectroscopic sample,and has no effect on the true high redshift sample for objects with redshifts.Thus,with this adjustment of the color selection criteria(which one would have chosen in any case in order to observe the same types of galaxies seen in the z∼3sample,as demonstrated in Figure1),the contamination of the spectroscopic sample can be reduced from25/73to12/60,with the loss of only2true high redshift galaxies.As can be seen from Table1,applying the new color cut reduces the number of candidates from244 to207.We regard this sample of207candidates as our primary photometric sample6,and the estimated contamination by interlopers is∼20%.4.DIFFERENTIAL COMPARISONS:z∼4VERSUS z∼34.1.Correcting for IncompletenessThe observed surface density of z∼4galaxies to a limit of I=25.0,Σ4(25)=0.20±0.02 arcmin−2,is significantly smaller than the observed surface density of z∼3galaxies to R=25.0,Σ3(25)=0.68±0.03arcmin−2.The I band samples the far–UV continuum of z∼4galaxies at very similar rest wavelengths as the R band at z∼3(by design),so that k-corrections between the two should be negligible;however,obviously one is sampling different parts of the luminosity function because of the larger luminosity distance for the z∼4sample.Our approach for comparing the two samples will be to truncate the z∼3sample at an apparent R magnitude that corresponds to an absolute far–UVflux density equivalent to I=25.0at z=4.13(the median redshift of the z∼4sample).This apparent magnitude is cosmology dependent:R=24.51for Einstein-de Sitter,R=24.31forΩ0=0.2open,and R=24.45forΩ0=0.3,ΩΛ=0.7.Thefirst step is to correct the samples for contamination by interlopers.The z∼4surface density was statistically corrected for contamination based on the spectroscopic results,as described above.At z∼3,the only known interlopers(other than QSOs,which we have also removed from the sample)are Galactic stars,which we have found empirically to have a surface density to R=24.0along the sightlines we sample ofΣstars=0.06arc min−2(and essentiallyzero at fainter apparent magnitudes).Thus,both samples have comparable contamination by interlopers,and both interloper populations(stars and early type galaxies)tend to populate the bright end of the apparent magnitude distribution;all corrections for contamination have been made as a function of apparent magnitude.Once interlopers have been removed from the samples,we can begin to estimate the comoving luminosity density at z∼3and z∼4from the observed surface density of U n and G dropouts. The main complication is that some fraction of the galaxies brighter than our magnitude limits at these redshifts are undoubtedly missing from our sample because of photometric errors,blending with foreground objects,and—more seriously—because they may have intrinsic colors which do not match our selection criteria.In order to investigate this incompleteness quantitatively,we have run Monte-Carlo simulations in which large numbers of artificial objects with a range of colors and magnitudes are added to our real images,and then recovered using the same methods employed for the real photometry.The complete results of these simulations will be presented in Adelberger et al.(1999,A99);but for the present they are useful mainly because they yield an estimate of the effective volume of our surveys as a function of apparent magnitude,V eff(m)≡ dz p(m,z)dV/dz,where p(m,z)is the probability a galaxy of apparent magnitude m(in R at z∼3and I atz∼4)at redshift z will be detected in our images and appear to match our photometric criteria, and dz dV/dz is the comoving volume per arcmin2at redshift z.As shown in A99,dividing the observed surface density of high redshift candidates by V eff(m)defined in this way compensates for our various selection biases and incompletenesses,and produces a maximum likelihood estimate of the comoving number density of galaxies with magnitude m at the observed redshifts.The galaxy number density estimated with this procedure is corrected not only for the usual“detection incompleteness”due to the declining probability of detecting a galaxy in our images at the faintest magnitudes(caused by both photometric errors and problems related to blending with foreground objects7),but also for“color incompleteness”due to detected galaxies having measured colors that may erroneously place them outside of our color-selection window,and even to some extent for the“template incompleteness”which would arise if some fraction of high-redshift galaxies had true colors that lay outside of our color-selection window.This last correction is possible because our U n G R sample(for example)could contain galaxies at z∼2.5much redder than the typical color we assume,and galaxies at z∼3.5much bluer,and we can therefore use data from these redshifts to estimate the fraction of galaxies whose colors will not match our selection criteria at z≃3,where most of our sample lies.We will return to this below.The effective volumes calculated from our Monte-Carlo simulations are provided,as a function of apparent magnitude,in Tables3and4.The incompleteness corrections implied by theseeffective volumes are significant,but because the corrections are comparable(to within∼30%)forthe z∼3and z∼4samples,they do not strongly affect our estimate of the change in luminosity density over this range of redshift.Very similar relative volumes at z∼3and z∼4would result, for example,from simply assuming a boxcar selection function with half-width given by the standard deviation(see Figure4)of the redshifts in each sample.The incompleteness corrections are important when we attempt to derive absolute UV luminosity densities at z∼3and z∼4, but this calculation is subject to other,probably larger,uncertainties,as we discuss below.4.2.Color and Luminosity DistributionsFrom these effective volumes it is straightforward to compute luminosity functions from the observed surface density of U n and G dropouts.It is of primary interest to compare the luminosity functions,and the integral luminosity densities,in the two redshift intervals.The most recent compilation from the Hubble Deep Field data is that of Madau,Pozzetti,&Dickinson(1998, MPD),which suggests a factor of∼2.5decline in the luminosity density between z∼2.75and z∼4(the original Madau et al.1996paper estimated the same decline at a factor of∼4).In contrast we see little evidence in our ground-based sample for luminosity density evolution from z∼4to z∼3.Figure5compares the U n-and G-dropout luminosity functions for an Einstein-de Sitter cosmology.The agreement in both the shape and normalization of the bright end of the luminosity functions at z∼3and z∼4is quite striking,and depends only mildly on cosmology(the other2cosmologies considered make the z∼4luminosity function slightly brighter relative to that at z∼3).To construct this plot from the comoving number densityof objects with apparent magnitude m AB,which we estimated above,we used the relationship Lν=10−0.4(48.60+m AB)4πd2L/(1+z)and adopted(for simplicity)Ωm=1luminosity distancesof d L=3.8×1028h−1cm for all objects in our z∼3sample,and d L=5.3×1028h−1cmfor all objects in our z∼4sample.These luminosity distances are appropriate for objects at the median observed redshifts of z =3.04and z =4.13.The corresponding luminosity distances forΩm=0.2open andΩm=0.3flat are d L=5.8,5.6×1028h−1cm at z =3.04and d L=9.0,8.1×1028h−1cm at z =4.13.The results of integrating the luminosity distributions over the same range of intrinsic luminosity(the smallest luminosity corresponds to the faintest objects in the z∼4sample,which is I=25.0,or M AB(1700˚A)=−21for the Einstein-de Sitter model H0=50km s−1Mpc−1[see Figure5]),as well as the ratios of the luminosity densities in the two redshift intervals,are given in Table5.In assigning errors to these luminosity densities,we have attempted to account for Poisson counting statistics,uncertainties in the contamination corrections,and for systematic uncertainties in the effective volumes discussed above.For all cosmologies we consider,the observed UV-luminosity density integrated to the luminosity equivalent of I AB=25.0at z=4.13shows no significant change between z =4.13 and z =3.04,in apparent conflict with several analyses based upon the HDF alone(e.g.Madau et al.(1996),MPD,Pozzetti et al.1998).We will return to this shortly.。

a r X i v :a s t r o -p h /9901140v 1 12 J a n 1999Mon.Not.R.Astron.Soc.000,1–8(1998)Printed 1February 2008(MN L A T E X style file v1.4)UBV I CCD photometry of two old open clusters NGC 1798and NGC 2192Hong Soo Park and Myung Gyoon Lee ⋆Department of Astronomy,Seoul National University,Seoul 151-742,KoreaAccepted 1998??.Received 1998??;in original form 1998July ??ABSTRACT We present UBV I CCD photometry of two open clusters NGC 1798and NGC 2192which were little studied before.Color-magnitude diagrams of these clusters show several features typical for old open clusters:a well-defined main-sequence,a red giant clump,and a small number of red giants.The main sequence of NGC 1798shows a distinct gap at V ≈16.2mag.From the surface number density distribution we have measured the size of the clusters,obtaining 8′.3(=10.2pc)for NGC 1798and 7′.3(=7.5pc)for NGC 2192.Then we have determined the reddening,metallicity,and distance of these clusters using the color-color diagrams and color-magnitude diagrams:E (B −V )=0.51±0.04,[Fe/H]=−0.47±0.15dex and (m −M )0=13.1±0.2(d =4.2±0.3kpc)for NGC 1798,and E (B −V )=0.20±0.03,[Fe/H]=−0.31±0.15dex and (m −M )0=12.7±0.2(d =3.5±0.3kpc)for NGC 2192.The ages of these clusters have been estimated using the morphological age indicators and the isochrone fitting with the Padova isochrones:1.4±0.2Gyrs for NGC 1798and 1.1±0.1Gyrs for NGC 2192.The luminosity functions of the main sequence stars in these clusters are found to be similar to other old open clusters.The metallicity and distance of these clusters are consistent with the relation between the metallicity and galactocentric distance of other old open clusters.Key words:Hertzsprung–Russell (HR)diagram –open clusters and associations:general –open clusters and associations:individual:NGC 1798,NGC 2192–stars:luminosity function.1INTRODUCTIONOld open clusters provide us with an important informationfor understanding the early evolution of the Galactic disk.There are about 70known old open clusters with age >1Gyrs (Friel 1995).These clusters are faint in general so thatthere were few studies about these clusters until recently.With the advent of CCD camera in astronomy,the numberof studies on these clusters has been increasing.However,there are still a significant number of old open clusters forwhich basic parameters are not well known.For example,metallicity is not yet known for about 30clusters amongthem.Recently Phelps et al.(1994)and Janes &Phelps (1994)presented an extensive CCD photometric survey of potentialold open clusters,the results of which were used in the studyon the development of the Galactic disk by Janes &Phelps(1994).In the sample of the clusters studied by Phelps et al.⋆corresponding author,E-mail:mglee@astrog.snu.ac.krthere are several clusters for which only the non-calibrated photometry is available.We have chosen two clusters among them,NGC 1798and NGC 2192,to study the characteristics of these clus-ters using UBV I CCD photometry.These clusters are lo-cated in the direction of anti-galactic centre.To date there is published only one photometric study of these clusters,which was given by Phelps et al.(1994)who presented non-calibrated BV CCD photometry of these clusters.From the instrumental color-magnitude diagrams of these clus-ters Phelps et al.estimated the ages of these clusters using the morphological age indicators,obtaining the values of 1.5Gyrs for NGC 1798and 1.1Gyrs for NGC 2192.However,no other properties of these clusters are yet known.In this paper we present a study of NGC 1798and NGC 2192based on UBV I CCD photometry.We have es-timated the basic parameters of these clusters:size,red-dening,metallicity,distance,and age.Also we have derived the luminosity function of the main sequence stars in these clusters.Section 2describes the observations and data re-duction.Sections 3and 4present the analysis for NGC 1798c 1998RAS2Hong Soo Park and Myung Gyoon Leeand NGC2192,respectively.Section5discusses the results. Finally Section6summarizes the primary results.2OBSER V ATIONS AND DATA REDUCTION 2.1ObservationsUBV I CCD images of NGC1798and NGC2192were obtained using the Photometrics512CCD camera at the Sobaeksan Observatory61cm telescope in Korea for several observing runs between1996November and1997October. We have used also BV CCD images of the central region of NGC1798obtained by Chul Hee Kim using the Tek1024 CCD camera at the Vainu Bappu Observatory2.3m tele-scope in India on March4,1998.The observing log is given in Table1.The original CCD images wereflattened after bias sub-traction and several exposures for eachfilter were combined into a single image for further reduction.The sizes of the field in a CCD image are4′.3×4′.3for the PM512CCD im-age,and10′.6×10′.6for the Tek1024CCD image.The gain and readout noise are,respectively,9electrons/ADU and 10.4electrons for the PM512CCD,and9electrons/ADU and10.4electrons for the Tek1024CCD.Figs.1and2illustrate grey scale maps of the V CCD images of NGC1798and NGC2192made by mosaicing the images of the observed regions.It is seen from thesefigures that NGC1798is a relatively rich open cluster,while NGC 2192is a relatively poor open cluster.2.2Data ReductionInstrumental magnitudes of the stars in the CCD images were obtained using the digital stellar photometry reduction program IRAF⋆/DAOPHOT(Stetson1987,Davis1994). The resulting instrumental magnitudes were transformed onto the standard system using the standard stars from Lan-dolt(1992)and the M67stars in Montgomery et al.(1993) observed on the same photometric nights.The transforma-tion equations areV=v+a V(b−v)+k V X+Z V,(B−V)=a BV(b−v)+k BV X+Z BV,(U−B)=a UB(u−b)+k UB X+Z UB,and(V−I)=a V I(v−i)+k V I X+Z V I,where the lower case symbols represent instrumental mag-nitudes derived from the CCD images and the upper case symbols represent the standard system values.X is the air-mass at the midpoint of the observations.The results of the transformation are summarized in Table2.The data ob-tained on non-photometric nights were calibrated using the photometric data for the overlapped region.The total number of the measured stars is1,416for NGC1798and409for NGC2192.Tables3and4list the⋆IRAF is distributed by the National Optical Astronomy Ob-servatories,which are operated by the Association of Universities for Research in Astronomy,Inc.under contract with the National Science Foundation.photometry of the bright stars in the C-regions of NGC1798 and NGC2192,respectively.The X and Y coordinates listed in Table3and4are given in units of CCD pixel(=0′′.50). The X and Y values are increasing toward north and west, respectively.We have divided the entire region of thefields into sev-eral regions,as shown in Figs.1and2,for the analysis of the data.The C-region represents the central region of the cluster,and the F-regions(F,Fb,Fir,and Fi regions)rep-resent the controlfield regions,and the N-region represents the intermediate region between the central region and the field region.The radius of the C-region is300pixel for NGC 1798and NGC2192.The ratio of the areas of the C-region, N-region,Fb-region,and(Fi+Fir)-regions for NGC1798is 1:1.50:1.00:1.07,and the ratio of the areas of the C-region, N-region,and F-region for NGC2192is1:1.26:0.98.3ANALYSIS FOR NGC17983.1The Size of the ClusterWe have investigated the structure of NGC1798using star-counts.The centre of the cluster is estimated to be at the po-sition of(X=710pixel,Y=1110pixel),using the centroid method.Fig.3illustrates the projected surface number den-sity profile derived from counting stars with V<19.5mag in the entire CCDfield.The magnitude cutofffor starcounts was set so that the counts should be free of any photometric incompleteness problem.Fig.3shows that most of the stars in NGC1798are concentrated within the radius of250pixel (=125′′),and that the outskirts of the cluster extend out to about500pixel(=250′′)from the center.The number density changes little with radius beyond500pixel,show-ing that the outer region of the observedfield can be used as a controlfield.Therefore we have estimated the approxi-mate size of NGC1798for which the cluster blends in with thefield to be about500′′in diameter,which corresponds to a linear size of10.2pc for the distance of NGC1798as determined below.3.2Color-Magnitude DiagramsFigs.4and5show the V−(B−V)and V−(V−I)color-magnitude diagrams(CMDs)of the measured stars in the observed regions in NGC1798.Thesefigures show that the C-region consists mostly of the members of NGC1798with some contamination of thefield stars,while the F-regions consist mostly of thefield stars.The N-region is intermediate between the C-region and the F-region.The distinguishable features seen in the color-magnitude diagrams of the C-region are:(a)There is a well-defined main sequence the top of which is located at V≈16 mag;(b)There is seen a distinct gap at V≈16.2mag in the main sequence,which is often seen in other old open clusters (e.g.M67);(c)There is a poorly defined red giant branch and these is seen some excess of stars around(B−V)=1.3 and V=15.6mag on this giant branch,which is remarked by the small box in thefigures.This may be a random excess of stars.However,the positions of the stars in the CMDs are consistent with the positions of known red giant clump in other old open clusters.Therefore most of these stars arec 1998RAS,MNRAS000,1–8UBV I CCD photometry of two old open clusters NGC1798and NGC21923probably red giant clump stars;and(d)There are a small number of stars along the locus of the red giant branch. 3.3Reddening and MetallicityNGC1798is located close to the galactic plane in the anti-galactic centre direction(b=4◦.85and l=160◦.76)so that it is expected that the reddening toward this cluster is significant.We have estimated the reddening for NGC1798 using two methods as follows.First we have used the mean color of the red giant clump.Janes&Phelps(1994)estimated the mean color and magnitude of the red giant clump in old open clusters to be (B−V)RGC=0.87±0.02and M V,RGC=0.59±0.09,when the difference between the red giant clump and the main sequence turn-offof the clusters,δV,is smaller than one. The mean color of the red giant clump in the C-region is estimated to be(B−V)RGC=1.34±0.01((V−I)RGC= 1.47±0.01,and(U−B)RGC=1.62±0.04),and the cor-responding mean magnitude is V RGC=15.57±0.05.δV is estimated to be0.8±0.2,which is the same value derived by Phelps et al.(1994).From these data we have derived a value of the reddening,E(B−V)=0.47±0.02.Secondly we have used the color-color diagram to es-timate the reddening and the metallicity simultaneously. We havefitted the mean colors of the stars in the C-region with the color-color relation used in the Padova isochrones (Bertelli et al.1994).This process requires iteration,because we need to know the age of the cluster as well as the red-dening and metallicity.We have iterated this process until all three parameters are stabilized.Fig.6illustrates the results offitting in the(U−B)−(B−V)color-color diagram.It is shown in thisfigure that the stars in NGC1798are reasonablyfitted by the color-color relation of the isochrones for[Fe/H]=−0.47±0.15 with a reddening value of E(B−V)=0.55±0.05. The error for the metallicity,0.15,was estimated by com-paring isochrones with different metallicities.As a reference the mean locus of the giants for solar abundance given by Schmidt-Kaler(1982)is also plotted in Fig.6.Finally we derive a mean value of the two estimates for the reddening, E(B−V)=0.51±0.04.3.4DistanceWe have estimated the distance to NGC1798using two methods as follows.First we have used the mean magnitude of the red giant clump.We have derived a value of the ap-parent distance modulus(m−M)V=14.98±0.10from the values for the mean magnitudes of the red giant clump stars described above.Secondly we have used the the zero-age main sequence (ZAMS)fitting,following the method described in Vanden-Berg&Poll(1989).VandenBerg&Poll(1989)presented the semi-empirical ZAMS as a function of the metallicity[Fe/H] and the helium abundance Y:V=M V(B−V)+δM V(Y)+δM V([Fe/H])whereδM V(Y)=2.6(Y−0.27)andδM V([Fe/H])=−[Fe/H](1.444+0.362[Fe/H]).Before the ZAMSfitting,we subtracted statistically the contribution due to thefield stars in the CMDs of the C-region using the CMDs of the Fb-region for BV photometry and the CMDs of the Fi+Fir region for V I photometry. The size of the bin used for the subtraction is∆V=0.25 and∆(B−V)=0.1.The resulting CMDs are displayed in Fig.7.We used the metallicity of[Fe/H]=–0.47as derived above and adopted Y=0.28which is the mean value for old open clusters(Gratton1982).Using this method we have obtained a value of the apparent distance modulus(m−M)V=14.5±0.2.Finally we calculate a mean value of the two estimates,(m−M)V=14.7±0.2.Adopting the extinction law of A V=3.2E(B−V),we derive a value of the intrinsic distance modulus(m−M)0=13.1±0.2.This corresponds to a distance of d=4.2±0.3kpc.3.5AgeWe have estimated the age of NGC1798using two methods as follows.First we have used the morphological age index (MAI)as described in Phelps et al.(1994).Phelps et al. (1994)and Janes&Phelps(1994)presented the MAI–δV relation,MAI[Gyrs]=0.73×10(0.256δV+0.0662δV2).From the value ofδV derived above,0.8±0.2mag,we obtain a value for the age,MAI=1.3±0.2Gyrs.Secondly we have estimated the age of the cluster us-ing the theoretical isochrones given by the Padova group (Bertelli et al.1994).Fitting the isochrones for[Fe/H]=–0.47to the CMDs of NGC1798,as shown in Fig.8,we estimate the age to be1.4±0.2Gyrs.Both results agree very well.3.6Luminosity FunctionWe have derived the V luminosity functions of the main sequence stars in NGC1798,which are displayed in Fig.9.The Fb-region was used for subtraction of thefield star contribution from the C-region and the magnitude bin size used is0.5mag.This controlfield may not be far enough from the cluster to derive thefield star contribution.If so,we might have oversubtracted thefield contribution,obtaining flatter luminosity functions than true luminosity functions. However,the fraction of the cluster members in thisfield must be,if any,very low,because the surface number density of this region is almost constant with the radius as shown in Fig.3.The luminosity function of the C-region in Fig. 9(a)increases rapidly up to V≈16.5mag,and stays almost flat for V>16.5mag.The luminosity functions of the N-region and the(R+Fir)-region are steeper than that of the C-region.A remarkable drop is seen at V=16.2mag(M V= 1.5mag)in the luminosity function of the C-region based on smaller bin size of0.2mag in Fig.9(b).This corresponds to the main sequence gap described above.4ANALYSIS FOR NGC21924.1The Size of the ClusterWe have investigated the structure of NGC2192using star-counts.We could not use the centroid method to estimatec 1998RAS,MNRAS000,1–84Hong Soo Park and Myung Gyoon Leethe centre of this cluster,because this cluster is too sparse. So we have used eye-estimate to determine the centre of the cluster to be at the position of(X=465pixel,Y=930 pixel).Fig.10illustrates the projected surface number den-sity profile derived from counting stars with V<18mag in the entire CCDfield.The magnitude cutofffor starcounts was set so that the counts should be free of any photomet-ric incompleteness problem.Fig.10shows that most of the stars in NGC2192are concentrated within the radius of200 pixel(=100′′),and that the outskirts of the cluster extend out to about440pixel(=220′′)from the centre.Therefore the approximate size of NGC2192is estimated to be about 440′′in diameter,which corresponds to a linear size of7.5pc for the distance of NGC2192as determined below.4.2Color-Magnitude DiagramsFigs.11and12show the V−(B−V)and V−(V−I)color-magnitude diagrams of the measured stars in the observed regions in NGC2192.The distinguishable features seen in the color-magnitude diagrams of the C-region are:(a)There is a well-defined main sequence the top of which is located at V≈14mag;(b)There are a group of red giant clump stars at(B−V)=1.1and V=14.2mag,which are remarked by the small box in thefigures;and(c)There are a small number of stars along the locus of the red giant branch. 4.3Reddening and MetallicityNGC2192is located11degrees above the galactic plane in the anti-galactic centre direction(b=10◦.64and l= 173◦.41)but higher than NGC1798so that it is expected that the reddening toward this cluster is significant but smaller than that of NGC1798.We have estimated the red-dening for NGC2192using two methods as applied for NGC 1798.First we have used the mean color of the red giant clump.The mean color of the red giant clump in the C-region is estimated to be(B−V)RGC=1.08±0.01((V−I)RGC=1.07±0.01,and(U−B)RGC=0.61±0.02),and the corresponding mean magnitude is V RGC=14.20±0.05.δV is estimated to be0.6±0.2,which is similar to the value derived by Phelps et al.(1994).From these data we have derived a value of the reddening,E(B−V)=0.19±0.03.Secondly we have used the color-color diagram to es-timate the reddening and the metallicity simultaneously. We havefitted the mean colors of the stars in the C-region with the color-color relation used in the Padova isochrones (Bertelli et al.1994).Fig.13illustrates the results offit-ting in the(U−B)−(B−V)color-color diagram.It is shown in thisfigure that the stars in NGC2192are rea-sonablyfitted by the color-color relation of the isochrones for[Fe/H]=−0.31±0.15dex with a reddening value of E(B−V)=0.21±0.01.The error for the metallicity,0.15, was estimated by comparing isochrones with different metal-licities.As a reference the mean locus of the giant for solar abundance given by Schmidt-Kaler is also plotted in Fig.13. Finally we derive a mean value of the two estimates for the reddening,E(B−V)=0.20±0.03.4.4DistanceWe have estimated the distance to NGC2192using two methods as for NGC1798.First we have used the mean magnitude of the red giant clump.We have derived a value of the apparent distance modulus(m−M)V=13.61±0.10 from the values for the mean magnitudes of the red giant clump stars described previously.Secondly we have used the ZAMSfitting.Before the ZAMSfitting,we subtracted statistically the contribution due to thefield stars in the CMDs of the C-region using the CMDs of the F-region.The size of the bin used for the subtraction is∆V=0.25and∆(B−V)=0.1.The resulting CMDs are displayed in Fig.14.We used the metallicity of[Fe/H]=–0.31as derived before and adopted Y=ing this method we have obtaineda value of the apparent distance modulus(m−M)V=13.1±0.2.Finally we calculate a mean value of the two estimates,(m−M)V=13.3±0.2.Adopting the extinction law of A V=3.2E(B−V),we derive a value of the intrinsic distance modulus(m−M)0=12.7±0.2.This corresponds to a distance of d=3.5±0.3kpc.4.5AgeWe have estimated the age of NGC2192using two methods as follows.First we have used the morphological age index. From the value ofδV derived above,0.6±0.2mag,we obtain a value for the age,MAI=1.1±0.2Gyrs.Secondly we have estimated the age of the cluster using the theoretical isochrones given by the Padova group(Bertelli et al.1994). Fitting the isochrones for[Fe/H]=–0.31to the CMDs of NGC2192,as shown in Fig.15,we estimate the age to be 1.1±0.1Gyrs.Both results agree very well.4.6Luminosity FunctionWe have derived the V luminosity functions of the main sequence stars in NGC2192,which are displayed in Fig.16.The F-region was used for subtraction of thefield star contribution from the C-region.The luminosity function of the C-region in Fig.16(a)increases rapidly up to V≈14 mag,and stays almostflat for V>15mag.The luminosity function of the N-region is steeper than that of the C-region. Fig.16(b)displays a comparison of the luminosity functions of NGC1798,NGC2192,and NGC7789which is another old open cluster of similar age(Roger et al.1994).Fig.16(b) shows that the luminosity functions of these clusters are similar in that they are almostflat in the faint part.The flattening of the faint part of the luminosity functions of old open clusters has been known since long,and is believed to be due to evaporation of low mass stars(Friel1995).5DISCUSSIONWe have determined the metallicity and distance of NGC 1798and NGC2192in this study.We compare them with those of other old open clusters here.Fig.17illustrates the radial metallicity gradient of the old open clusters com-piled by Friel(1995)and supplemented by the data in Wee&Lee(1996)and Lee(1997).Fig.17shows that thec 1998RAS,MNRAS000,1–8UBV I CCD photometry of two old open clusters NGC1798and NGC21925 mean metallicity decreases as the galactocentric distance in-creases.The positions of NGC1798and NGC2192we haveobtained in this study are consistent with the mean trendof the other old open clusters.The slope we have deter-mined for the entire sample including these two clusters is∆[Fe/H]/R GC=−0.086±0.011dex/kpc,very similar tothat given in Friel(1995),∆[Fe/H]/R GC=−0.091±0.014dex/kpc.There are only four old open clusters located beyondR GC=13kpc in Fig.17.These four clusters follow the meantrend of decreasing outward.However,the number of theclusters is not large enough to decide whether the metallictykeeps decreasing outward or it stops decreasing somewherebeyond R GC=13kpc and stays constant.Further studiesof more old open clusters beyond R GC=13kpc are neededto investigate this point.6SUMMARY AND CONCLUSIONSWe have presented UBV I photometry of old open clustersNGC1798and NGC2192.From the photometric data wehave determined the size,reddening,metallicity,distance,and age of these clusters.The luminosity functions of themain sequence stars in these clusters are similar to those ofthe other old open clusters.The basic properties of theseclusters we have determined in this study are summarizedin Table5.ACKNOWLEDGMENTSProf.Chul Hee Kim is thanked for providing the BV CCDimages of NGC1798.This research is supported in part bythe Korea Science and Engineering Foundation Grant No.95-0702-01-01-3.REFERENCESBertelli,G.,Bressan,A.,Chiosi,C.,Fagotto,F.,&Nasi,E.1994,A&AS,106,275Davis,L.E.,1994,A Reference Guide to the IRAF/DAOPHOTPackageFriel,E.D.1995,ARA&A,33,381Gratton,R.G.,1982,ApJ,257,640Janes,K.,&Phelps,R.L.1994,AJ,108,1773Landolt,A.U.,1992,AJ,104,340Lee,M.G.,1997,113,729Montgomery,K.A.,Marschall,L.A.,&Janes,K.A.1993,AJ,106,181Phelps,R.L.,Janes,K.,&Montgomery,K.A.,1994,AJ,107,1079Roger,C.M.,Paez,E.,Castellani,V.,&Staniero,O.1994,A&A,290,62Schmidt-Kaler,T.1982,in Landolt-Bornstein VI,2b(Berlin:Springer)Stetson,P.B.,1987,PASP,99,191VandenBerg,D.A.,&Poll,H.E.,1989,AJ,98,1451Wee,S.O.,&Lee,M.G.,1996,Jour.Korean Astro.Soc.,29,181This paper has been produced using the Royal AstronomicalSociety/Blackwell Science L A T E X stylefile.c 1998RAS,MNRAS000,1–86Hong Soo Park and Myung Gyoon LeeTable2.Transformation coefficients for the standard stars.Date Color a k Z rms n(stars) 96.11.11V0.003–0.101–6.0400.00919(B−V) 1.090–0.155–0.4670.01317(U−B) 1.008–0.154–1.7110.03416 97.02.11V0.028–0.198–6.0500.00934(B−V) 1.150–0.118–0.5930.01035(U−B) 1.079–0.324–1.5750.03226(V−I)0.983–0.1300.3020.00829 97.02.13V–0.007–0.176–6.0050.01034(B−V) 1.160–0.133–0.5880.01334(U−B) 1.079–0.349–1.5260.02320(V−I)0.986–0.0970.2710.01532 97.03.17V-0.019–0.225–6.0680.01548(B−V) 1.221–0.093–0.7810.01844(U−B) 1.008–0.309–1.4580.02735(V−I)0.956–0.1570.3140.02052Table 3.UBV I photometry of the bright stars in the C-regionof NGC1798.ID X[px]Y[px]V(B−V)(U−B)(V−I) 1723.21110.815.8600.7790.3240.9143680.51092.015.380 1.3250.627 1.5254746.01160.315.9050.7410.2200.9545741.81165.514.380 1.4830.880 1.6336684.61030.115.8140.8640.342 1.0427745.31073.315.3760.9200.237 1.0849707.21038.814.777 1.4860.723 1.653 11549.41153.715.305 1.5290.915 1.666 12547.91162.714.846 1.6270.947 1.764 13602.31068.015.325 1.5240.847 1.660 14598.11080.815.776 1.3340.575 1.490 15525.81116.815.510 1.0020.346 1.169 18833.91144.214.976 1.4940.866 1.578 21981.91125.114.711 1.510 1.031 1.440 26835.71098.015.706 1.3180.468 1.407 27656.51022.115.653 1.4160.180 1.571 28659.8955.915.216 1.2160.384 1.385 29656.4976.813.6670.6610.3100.777 30674.2822.512.0330.4450.0500.532 33668.7966.315.687 1.3130.641 1.446 34764.3879.915.460 1.3370.508 1.408 38749.01008.115.359 1.3220.744 1.426 39774.4965.915.545 1.3040.590 1.402 43571.8930.612.875 1.970 1.264 2.252 45512.8908.715.810 1.3480.474 1.485 46642.1949.515.622 1.3290.590 1.477 48732.61211.315.821 1.3530.643 1.492 50678.81210.515.297 1.3680.770 1.501 51742.11244.414.7990.747-0.046 1.216 52673.11250.215.180 1.3060.780 1.457 56728.21183.415.665 1.4050.803 1.545 57614.91229.413.085 2.1770.635 3.581 62563.01338.415.9090.7060.6380.778 65913.91203.013.686 1.2490.851 1.354 67792.71314.215.6010.9750.470 1.275 68932.61268.414.4660.7170.1970.763 70801.11338.715.561 1.3270.785 1.442 72827.61315.513.5260.9670.521 1.161 78444.01094.814.605 1.5790.825 1.723 82684.3822.615.8280.9510.128 1.189 97598.51330.315.580 1.3360.710 1.483Table4.UBV I photometry of the bright stars in the C-region of NGC2192.ID X[px]Y[px]V(B−V)(U−B)(V−I) 4502.4879.614.9830.4320.1140.424 5537.5891.712.9690.9240.4750.930 7535.1931.315.1700.598-0.2010.483 9434.8947.613.6760.570-0.0560.648 10562.3991.914.037 1.0960.612 1.043 11412.9884.814.165 1.0780.608 1.072 12598.4778.715.1840.464-0.0300.477 13595.9930.014.4800.5020.1720.549 14625.8971.814.7430.7200.0890.741 16614.3684.214.3970.7660.1750.758 17463.3689.514.7660.4660.0120.480 18553.3710.715.4920.447-0.1350.428 19591.7723.814.4660.5450.0930.566 21623.0867.712.634 1.1020.713 1.108 22648.0929.015.3380.3940.1150.399 26461.1711.314.162 1.0860.670 1.091 29583.9802.315.0940.600-0.0160.644 32720.4889.515.3260.3700.0710.410 37395.9778.315.2640.3960.0310.379 38405.5778.514.8900.4810.1010.409 40258.21042.915.4310.4240.1200.484 42376.6883.915.1870.4550.1360.470 44180.1908.714.3200.2870.1120.295 47367.1938.314.8970.4030.2520.459 51183.3998.714.202 1.1140.552 1.108 55475.81052.514.6370.3880.1670.465 56389.11055.113.6060.6520.2560.777 58481.41074.114.3470.4500.1150.520 59514.91085.115.0970.4290.1370.517 60478.51089.614.2360.5280.1590.582 61498.51127.914.6090.5090.1350.578 63278.71154.414.372 1.0700.599 1.053 64527.41158.715.4180.4460.2450.510 65343.41167.814.266 1.0120.618 1.035 66362.21169.314.2660.8790.4690.879 74346.91039.814.5810.4520.1240.510 77688.91124.215.4200.3900.2900.400 83678.91079.715.4950.4640.1070.504 84624.21042.813.5010.3850.2170.389 88579.61028.914.8250.4560.1620.530 Table5.Basic properties of NGC1798and NGC2192.Parameter NGC1798NGC2192RA(2000)5h11m40s6h15m11sDEC(2000)47◦40′37′′39◦51′1′′l160◦.76173◦.41b4◦.8510◦.64Age1.4±0.2Gyrs1.1±0.1GyrsE(B−V)0.51±0.040.20±0.04[Fe/H]−0.47±0.15dex−0.31±0.15dex(m−M)013.1±0.212.7±0.2distance4.2±0.3kpc3.5±0.3kpcR GC12.5kpc11.9kpcz355pc646pcdiameter10.2pc(8′.3)7.5pc(7′.3)c 1998RAS,MNRAS000,1–8UBV I CCD photometry of two old open clusters NGC1798and NGC21927 Table1.Observing log for NGC1798and NGC2192.Date Target Filter Seeing Telescope Condition96.11.11NCC1798UBV2′′.3SAO a-61cm Photometric97.01.12NCC1798UBV I2′′.2SAO-61cm Non-photometric97.02.12NCC1798,NGC2192UBV I3′′.3SAO-61cm Photometric97.02.13NCC1798,NGC2192UBV I2′′.5SAO-61cm Non-photometric97.03.17NCC2192UBV I2′′.2SAO-61cm Photometric97.10.21NCC1798BV I2′′.3SAO-61cm Non-photometric97.10.24NCC2192BV I2′′.7SAO-61cm Non-photometric97.03.04NCC1798BV2′′.7VBO b-2.3m Non-photometrica Sobaeksan Astronomical Observatoryb Vainu Bappu Observatoryc 1998RAS,MNRAS000,1–8。