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Detailed Description of J/ApJS/192/10 :
Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)

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Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.
J/ApJS/192/10     Chandra ACIS survey in 383 nearby galaxies. I.     (Liu, 2011)
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Chandra ACIS survey of X-ray point sources in 383 nearby galaxies.
I. The source catalog.
    Liu J.
   <Astrophys. J. Suppl. Ser., 192, 10 (2011)>
   =2011ApJS..192...10L
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ADC_Keywords: X-ray sources ; Galaxies, nearby ; Surveys

Keywords: catalogs - galaxies: general - X-rays: binaries - X-rays: galaxies


Abstract:
    By 2007 December 14, 383 galaxies within 40Mpc with isophotal major
    axis above 1arcmin had been observed by 626 public Chandra/ACIS
    observations, most of which were for the first time analyzed by this
    survey to study the X-ray point sources. Uniform data analysis
    procedures are applied to the 626 ACIS observations and lead to the
    detection of 28099 point sources, which belong to 17599 independent
    sources. These include 8700 sources observed twice or more and 1000
    sources observed 10 times or more, providing us a wealth of data to
    study the long-term variability of these X-ray sources.
    Cross-correlation of these sources with galaxy isophotes led to 
    8519 sources within the D25 isophotes of 351 galaxies, 3305 
    sources between the D25 and 2D25 isophotes of 309 galaxies, and
    additionally 5735 sources outside 2D25 isophotes of galaxies. This
    survey has produced a uniform catalog, by far the largest, of 11824
    X-ray point sources within 2D25 isophotes of 380 galaxies.
    Contamination analysis using the log N-log S relation shows that 74%
    of sources within 2D25 isophotes above 1039erg/s, 71% of sources
    above 1038erg/s, 63% of sources above 1037erg/s, and 56% of all
    sources are truly associated with galaxies. Meticulous efforts have
    identified 234 X-ray sources with galactic nuclei of nearby galaxies.
    This archival survey leads to 300 ultraluminous X-ray sources (ULXs)
    with LX(0.3-8keV)>=2x1039erg/s within D25 isophotes, 179 ULXs
    between D25 and 2D25 isophotes, and a total of 479 ULXs within 188
    host galaxies, with about 324 ULXs truly associated with host galaxies
    based on the contamination analysis.

Description:
    The nearby galaxy sample is extracted from the Third Reference Catalog
    of Galaxies (RC3; de Vaucouleurs et al. 1991, Cat. VII/155). The 626
    ACIS observations selected for this survey include 83 ACIS-I
    observations and 543 ACIS-S observations. We have placed the 626 ACIS
    observations into 320 groups based on the proximity of the pointings.
    Observations are listed in table 2.

File Summary:

FileName Lrecl Records Explanations
× 80 . This file × ReadMe 80 . This file × table1.dat 123 391 Properties of surveyed galaxies × table2.dat 74 667 Groups of surveyed galaxies and ACIS observations × table3.dat 164 52542 Individual observations of X-ray sources × table4.dat 164 17559 X-ray point sources in nearby galaxies × table5.dat 104 391 X-ray identifications for galactic nuclei of nearby galaxies × table6.dat 157 480 Ultraluminous X-ray sources in nearby galaxies × table7.dat 157 70 Ultraluminous supersoft X-ray sources in nearby galaxies × refs.dat 116 32 References for table 1
See also: B/chandra : The Chandra Archive Log (CXC, 1999-) J/MNRAS/376/960 : X-ray emission from the Sombrero galaxy (Li+, 2007) J/ApJ/662/525 : LMXBs in globular clusters of 5 galaxies (Kundu+, 2007) J/AJ/132/1372 : Chandra observation of NGC 6822 (Tennant+, 2006) J/MNRAS/362/1065 : XMM/Chandra study of IC 10 (Wang+, 2005) J/ApJS/150/19 : ChaMP. I. First X-ray source catalog (Kim+, 2004) J/ApJ/610/247 : M31 supersoft and quasi-soft X-ray sources (Di Stefano+, 2004) J/ApJ/602/231 : Chandra X-ray point sources in nearby galaxies (Colbert+ 2004) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Gal Galaxy name (NGC, IC or PGC) 10- 18 A9 --- r_Gal Galaxy reference(s) (1) 20- 25 F6.2 deg GLON Galactic longitude of the galaxy 27- 32 F6.2 deg GLAT Galactic latitude of the galaxy 34- 38 F5.2 arcmin R25 Semimajor axis of the D25 isophotal ellipsis 40- 44 F5.2 arcmin r25 Semiminor axis of the D25 isophotal ellipsis 46- 53 E8.3 cm-2 nH Galactic HI column density (2) 55- 61 F7.4 Mpc Dist Distance 63- 65 A3 --- r_Dist Distance reference; see refs.dat file 67- 76 A10 --- MType Morphological type from RC3 (3) 78- 81 F4.1 --- TT ? Hubble type T of galaxies taken from RC3 83- 89 E7.2 Lsun LB ? Blue luminosity (4) 91 A1 --- l_F60um Limit flag on F60um 92- 99 E8.2 Jy F60um ? 60um flux density from IRAS (5) 101-103 I3 --- Group [1/320]? Group number as in table 2 105-111 E7.2 10-7W Flim 0.3-8keV flux of the faintest X-ray source in this galaxy 113-123 A11 --- Class NED classification (6)
Note (1): Point source catalogs of 50 galaxies are present in the VizieR service; see refs.dat file. Note (2): taken from the dust map by Dickey & Lockman (1990) Note (3): In the type code S stands for spiral, E for elliptical, S0 for lenticular, I for irregular; (r) for inner ring, (s) for S-shaped, (rs) for mixed; B for barred, A for non-barred, AB for mixed; Im for Magellanic irregular, I0 for non-Magellanic irregular; the trailing -/o/+ for early/intermediate/late stage, etc. The detailed explanations can be found in the RC3 catalog (p. 15, Vol. I). Note (4): The blue luminosity calculated from the apparent blue magnitude taken from RC3. The luminosity is expressed in unit of solar luminosity assuming an absolute blue magnitude of 5.47 for the Sun. Note (5): The flux density at 60um taken from the IRAS point source catalog (IPAC, 1986), with some nearby galaxies from Rice et al. (1988). When the galaxy is below detection, the 3{sigma} upper limit is calculated by adopting noise levels of 8.5mJy/arcmin2 for 60um (Rice et al. 1988). Note (6): Whether the galaxy is an HII/starburst/LINER/Seyfert galaxy, as extracted from the NED classification.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Group [1/320] Group number 5- 12 A8 --- Gal Galaxy name 14- 15 I2 --- Nobs Number of observations 17- 23 I7 s ExpTot Total exposure time 25- 28 I4 --- ObsID Observation number 30- 39 A10 "YYYY/MM/DD" ObsDate Observation date 41- 49 F9.3 d MJD Modified Julian Date of observation 51- 56 I6 s Exp ? Exposure time 58- 64 A7 --- Chip Chips used for analysis 66- 70 F5.2 --- Bkgd ? Average background (1) 72- 74 I3 --- Npt ? Total number of point sources detected
Note (1): The average background for the on-axis chip in unit of photons per 100 pixels, computed using 0.1-8keV photons outside three times of the source regions of detected sources.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Group [1/320] Group number 5- 7 A3 --- --- [CXO] 8- 28 A21 --- CXO Source name (JHHMMSS.sss+DDMMSS.ss) (1) 30- 47 A18 --- IDet Individual detection designation (2) 49- 54 I6 s Exp Exposure time after deadtime correction 56- 64 F9.3 d MJD Modified Julian Date of observation 66- 68 I3 arcsec OAA Off-axis angle 70- 74 F5.3 --- VigF Vignetting factor (3) 76- 79 F4.2 arcsec eRA ? Right Ascension statistical positional error 81- 84 F4.2 arcsec eDE ? Declination statistical positional error 86- 89 F4.1 arcsec ePos ? Source positional uncertainty (4) 91- 96 F6.1 --- Sigma Detection significance (5) 98-104 F7.1 ct Cts Background-subtracted photon counts (6) 106-110 F5.1 ct e_Cts Uncertainty in Cts 112-118 F7.1 ct bgct ? Expected background counts (7) 120-124 F5.2 --- CMS ? The (M-S)/(H+M+S) X-ray color (8) 126-129 F4.2 --- e_CMS ? Uncertainty in CMS 131-135 F5.2 --- CHM ? The (H-M)/(H+M+S) X-ray color (8) 137-140 F4.2 --- e_CHM ? Uncertainty in CHM 142-149 E8.2 mW/m2 FX Source flux; in erg/s/cm2 (9) 151-159 E9.2 --- PKS ? Kolmogorov-Smirnov variability probability (10) 161-164 A4 --- SQH Source description (11)
Note (1): Composed from their positions following CXO naming conventions. Note (2): In the form of IIIi.ss.nn, with IIIi as the observation ID, ss as the CCD chip, and nn as the source number from wavdetect (nn=u if the source was not detected in an observation). Enclosed in parenthesis is the split fraction, which is less than unity if the source is a split component of a merged source in an observation. Note (3): Derived from the exposure map as the ratio between the local and the maximum map value. Note (4): Computed from the scheme of Kim et al. (2004, Cat. J/ApJS/150/19). Note (5): From wavdetect. For the upper limit, it is computed as (net count)/(count error) and prefixed with a minus sign. Note (6): From wavdetect or computed from a circular region equivalent to the PSF enclosing 95% of the energy at 1.5keV for the upper limit. Note (7): Within the source region as computed in Section 3.2 for detected sources. Note (8): H/M/S stands for background-subtracted photon counts in hard (2-8keV), medium (1-2keV) and soft (0.3-1keV) bands. Note (9): Computed from the vignetting corrected count rate in 0.3-8keV assuming a power law of {Gamma}=1.7 and Galactic nH absorption. Note (10): Probability that a source is constant within an observation. A source is considered as variable if PKS<0.01. Note (11): Sources as follows: SSS = supersoft; QSS = quasi-soft; hard = hard phase; dim = too dim, i.e. below 10 counts.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Group [1/320] Group number 5- 7 A3 --- --- [CXO] 8- 28 A21 --- CXO Source name (JHHMMSS.sss+DDMMSS.ss) (1) 30- 34 F5.2 arcsec ePos Source positional uncertainty (2) 36- 47 A12 --- Name Galatic source name (3) 49- 54 F6.3 arcmin alpha ? Galactic source nuclear separation 56- 59 F4.2 --- r25 ? Galactic source nuclear separation (4) 61- 68 F8.4 Mpc Dist Distance to source 70- 74 A5 --- V/D Ratio of time source was observed to detected 76- 84 E9.4 10-7W LX Maximum computed luminosity; in erg/s 86- 93 E8.3 mW/m2 FX Average computed X-ray flux; in erg/s/cm2 95-100 F6.1 --- F/F The Fmax/Fmin flux ratio (5) 102-108 F7.3 --- E_F/F ? Positive error in F/F 110-116 F7.3 --- e_F/F ? Negative error in F/F 118-125 F8.3 --- Sigmax Maximum detection significance 127-135 F9.3 --- Cmax Maximum photon counts from detections 137-148 A12 --- SQH Phase statistics (6) 150-153 A4 --- PKS K-S criterion variability statistics (7) 155-164 A10 --- Note Source identification (8)
Note (1): Composed from their positions following CXO naming conventions. Note (2): Computed from the scheme of Kim et al. (2004, Cat. J/ApJS/150/19). Note (3): Numbered sequentially by its maximum detection significance. Note (4): In units of the elliptical radius. Note (5): As a variability indicator. Fmax is the maximum 0.3-8keV flux from all detections and Fmin is the minimum flux from all detections and upper limits. The ratio is unity without errors if Fmax and Fmin are the same. Note (6): Statistics for supersoft/quasisoft/hard/dim phases. For example, s2 means supersoft in two observations, q3 means quasisoft in three observations, h4 means hard in four observations, and d1 means too dim (below 10 counts) in one observations. Note (7): Statistics for variability within single observations by the K-S criterion. For example, v/3 means the source was variable by the K-S criterion (i.e., PKS<0.01, more than 10 counts, and the background fraction is <10%) in three observations. Note (8): Sources as follows: ULX = ultraluminous X-ray source; ULS = ultraluminous supersoft source; NGC3031 = the galactic nucleus for NGC1313.
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Group [1/320] Group number 5- 12 A8 --- Gal Galaxy name 14 I1 --- N6 ? Number of X-ray sources within 6" of the galactic nucleus 16- 17 I2 --- N12 ? Number of X-ray sources within 12" of the galactic nucleus 19- 20 I2 --- Nf ? Number of HST images in different filters available for the galactic nuclei region 22- 45 A24 --- XID CXO counterpart 47 I1 --- pos ? Position flag (1) 49 I1 --- ext ? X-ray source extendness flag (2) 51- 52 I2 --- V Numbers the source was observed 54- 55 I2 --- D Numbers the source was detected 57- 65 E9.4 10-7W LXmax Maximum X-ray luminosity in 0.3-8keV among all detections 67- 74 E8.3 10-7W LXmin ? Minimum X-ray luminosity in 0.3-8keV among all detections 76- 83 F8.2 ct CntMax ? Maximum X-ray photon counts among all detections 85- 91 F7.2 --- Sigmax ? Maximum detection sigma among all detections 93-104 A12 --- SQH Statistics for supersoft/quasi-soft/hard/dim phases (3)
Note (1): Position flag as follows: 1 = the X-ray and optical positions align up within the X-ray positional error, 2 = offset in excess of the X-ray positional error presents when there is a clear optical nucleus from DSS or HST images; 3 = alignment 4 = misalignment when the optical nucleus is extended. Note (2): X-ray source extendness flag as follows: 1 = perfect point source, 2 = there is slight extended emission, 3 = extended emission is moderate, 4 = the source is dominantly extended emission. Note (3): For example, s2 means supersoft in two observations, q3 means quasi-soft in three observations, h4 means hard in four observations, and d1 means too dim (below 10 counts) in one observations.
Byte-by-byte Description of file: table6.dat table7.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Group [1/320] Group number 5- 7 A3 --- --- [CXO] 8- 29 A22 --- CXO CXO designation (JHHMMSS.sss+DDMMSS.ss) 30- 33 F4.2 arcsec ePos Source positional uncertainties computed from the scheme of Kim et al. (2004) 35- 46 A12 --- Name Galactic source name (1) 48- 53 F6.3 arcmin alpha Galactic source nuclear separation 55- 58 F4.2 --- r25 Galactic source nuclear separation in unit of the elliptical radius 60- 66 F7.3 Mpc Dist Distance for the source 68- 69 I2 --- V Numbers the source was observed 71- 72 I2 --- D Numbers the source was detected 74- 81 E8.3 10-7W LXmax Maximum luminosity in erg/s computed from detections 83- 90 E8.3 10-3W/m2 FX Average flux in erg/s/cm2 computed from detections 92- 97 F6.1 --- F/F Fmax/Fmin ratio as a variability indicator (2) 99-104 F6.3 --- E_F/F ? Positive error in F/F 106-111 F6.3 --- e_F/F ? Negative error in F/F 113-121 F9.4 --- Sigmax The maximum detection significance 123-131 F9.3 --- Cmax The maximum photon counts from detections 133-144 A12 --- SQH Statistics for supersoft/quasi-soft/hard/dim phases (3) 146-148 A3 --- PKS K-S criterion variability (4) 150-157 A8 --- Notes Source identification (ULX/ULS)
Note (1): numbered sequentially by its maximum detection significance. Note (2): Fmax is the maximum 0.3-8keV flux from all detections, and Fmin is the minimum flux from all detections and upper limits. The ratio is unity without errors if Fmax and Fmin are the same. Note (3): For example, s2 means supersoft in two observations, q3 means quasi-soft in three observations, h4 means hard in four observations, and d1 means too dim (below 10 counts) in one observations. Note (4): Statistics for variability within single observations by the K-S criterion. For example, v:3 means the source was variable by the K-S criterion (i.e., PK-S<0.01, more than 10 counts, and the background fraction is <10%) in three observations.
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 3 A3 --- Ref Reference code 5- 23 A19 --- BibCode Bibcode 25- 42 A18 --- Aut Author's name 44-116 A73 --- Note Comment or catalog reference in VizieR
History: From electronic version of the journal ================================================================================ (End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 30-Mar-2011