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J/ApJS/184/158           Chandra COSMOS survey I.                 (Elvis+, 2009)

The Chandra COSMOS survey. I. Overview and point source catalog. Elvis M., Civano F., Vignali C., Puccetti S., Fiore F., Cappelluti N., Aldcroft T.L., Fruscione A., Zamorani G., Comastri A., Brusa M., Gilli R., Miyaji T., Damiani F., Koekemoer A.M., Finoguenov A., Brunner H., Urry C.M., Silverman J., Mainieri V., Hasinger G., Griffiths R., Carollo M., Hao H., Guzzo L., Blain A., Calzetti D., Carilli C., Capak P., Ettori S., Fabbiano G., Impey C., Lilly S., Mobasher B., Rich M., Salvato M., Sanders D.B., Schinnerer E., Scoville N., Shopbell P., Taylor J.E., Taniguchi Y., Volonteri M. <Astrophys. J. Suppl. Ser., 184, 158-171 (2009)> =2009ApJS..184..158E
ADC_Keywords: X-ray sources ; Surveys Mission_Name: Chandra Keywords: catalogs - cosmology: observations - galaxies: evolution - quasars: general - surveys - X-rays: general Abstract: The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8Ms, Chandra program that has imaged the central 0.5deg2 of the COSMOS field (centered at 10h, +02d) with an effective exposure of ∼160ks, and an outer 0.4deg2 area with an effective exposure of ∼80ks. The limiting source detection depths are 1.9x10-16erg/cm2/s in the soft (0.5-2keV) band, 7.3x10-16erg/cm2/s in the hard (2-10keV) band, and 5.7x10-16erg/cm2/s in the full (0.5-10keV) band. Here we describe the strategy, design, and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of <2x10-5 (1655 in the full, 1340 in the soft, and 1017 in the hard bands). By using a grid of 36 heavily (∼50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (±12%) exposure across the inner 0.5deg2 field was obtained, leading to a sharply defined lower flux limit. The widely different point-spread functions obtained in each exposure at each point in the field required a novel source detection method, because of the overlapping tiling strategy, which is described in a companion paper. This method produced reliable sources down to a 7-12 counts, as verified by the resulting logN-logS curve, with subarcsecond positions, enabling optical and infrared identifications of virtually all sources, as reported in a second companion paper. Description: A summary of the Chandra ACIS-I C-COSMOS observations as carried out is given in Table 3. The observations took place in two main blocks: 2006 December-2007 January and 2007 April-June. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 61 49 Chandra-COSMOS observation summary catalog.dat 289 1761 C-COSMOS bright source catalog
See also: II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007) J/ApJS/172/29 : XMM-Newton survey in COSMOS field. I. (Hasinger+, 2007) J/A+A/497/635 : XMM-Newton wide-field survey in COSMOS field (Cappelluti+ 2009) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Obs Observation number 6- 8 A3 --- Field COSMOS field 10- 19 A10 "YYYY/MM/DD" Date Observation start (UT) 21- 25 A5 --- Time Time of observation start (hh:mm) 27- 30 F4.1 ks Exp Exposure time (1) 32- 33 I2 h RAh Hour of right ascension (J2000) 35- 36 I2 min RAm Minute of right ascension (J2000) 38- 42 F5.2 s RAs Second of right ascension (J2000) 44 A1 --- DE- Sign of declination (J2000) 45- 46 I2 deg DEd Degree of declination (J2000) 48- 49 I2 arcmin DEm Arcminute of declination (J2000) 51- 55 F5.2 arcsec DEs Arcsecond of declination (J2000) 57- 61 F5.1 deg Roll Roll angle of the COSMOS field
Note (1): After GTI and high-background filtering for two affected obsids. Intervals of 8.50ks and 2.45ks (respectively) were eliminated from the two affected ObsIDs (8003, 8014).
Byte-by-byte Description of file: catalog.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [CXOC] 6- 21 A16 --- CXOC Chandra-COSMOS source name (JHHMMSS.s+DDMMSS) 23- 27 I5 --- Seq Source identification 29- 38 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000) 40- 47 F8.6 deg DEdeg Declination in decimal degrees (J2000) 49- 52 F4.2 arcsec ePos Positional uncertainty 54- 62 E9.2 ct/s FRate ?=-99 Full 0.5-7keV count rate (1) 64- 71 E8.2 ct/s e_FRate Error in FRate 73- 81 E9.2 mW/m2 FFlux ?=-99 Full 0.5-10keV flux; gamma=1.4 (1) 83- 90 E8.2 mW/m2 e_FFlux Error in FFlux 92- 97 F6.2 --- FSNR ?=-99 Full 0.5-7keV signal-to-noise (1) 99-104 F6.2 ks FExp ?=-99 Full 0.5-7keV exposure time (1) 106-111 F6.1 ct FctsA ?=-99 Full 0.5-7keV aperture photometry net counts 113-117 F5.1 ct e_FctsA ?=-99 Error in FctsA (1) 119-124 F6.2 ks FExpA ?=-99 Full 0.5-7keV exposure time from aperture photometry 126-134 E9.2 ct/s SRate ?=-99 Soft 0.5-2keV count rate (1) 136-143 E8.2 ct/s e_SRate Error in SRate 145-153 E9.2 mW/m2 SFlux ?=-99 Soft 0.5-2keV flux; gamma=1.4 (1) 155-162 E8.2 mW/m2 e_SFlux Error in SFlux 164-169 F6.2 --- SSNR ?=-99 Soft 0.5-2keV signal-to-noise (1) 171-176 F6.2 ks SExp ?=-99 Soft 0.5-2keV exposure time (1) 178-183 F6.1 ct SctsA ?=-99 Soft 0.5-2keV aperture photometry net counts (1) 185-189 F5.1 ct e_SctsA ?=-99 Error in SctsA (1) 191-196 F6.2 ks SExpA ?=-99 Soft 0.5-2keV exposure time from aperture photometry 198-206 E9.2 ct/s HRate ?=-99 Hard 2-7keV count rate (1) 208-215 E8.2 ct/s e_HRate Error in HRate 217-225 E9.2 mW/m2 HFlux ?=-99 Hard 2-10keV flux; gamma=1.4 (1) 227-234 E8.2 mW/m2 e_HFlux Error in HFlux 236-241 F6.2 --- HSNR ?=-99 Hard 2-7keV signal-to-noise (1) 243-248 F6.2 ks HExp ?=-99 Hard 2-7keV exposure time (1) 250-255 F6.1 ct HctsA ?=-99 Hard 2-7keV aperture photometry net counts 257-261 F5.1 ct e_HctsA ?=-99 Error in HctA (1) 263-268 F6.2 ks HExpA ?=-99 Hard 2-7keV exposure time from aperture photometry 270-275 F6.2 --- HR ?=-99 Hardness ratio; (H-S)/(H+S) (1) 277-282 F6.2 --- HRup ?=-99 The 90% lower limit on HR (1) 284-289 F6.2 --- HRlow ?=-99 The 90% upper limit on HR (1)
Note (1): A -99 indicates a NULL value. In cases where the main value is -99 but its error is not -99 the given error value represents the 90% upper limit.
History: From electronic version of the journal References: Puccetti et al. Paper II. 2009ApJS..185..586P.
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 08-Feb-2010
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