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J/ApJ/577/738       M31 Chandra X-ray point sources          (Kong+, 2002)

X-ray point sources in the central region of M31 as seen by Chandra. Kong A.K.H., Garcia M.R., Primini F.A., Murray S.S., di Stefano R., McClintock J.E. <Astrophys. J. 577, 738 (2002)> =2002ApJ...577..738K
ADC_Keywords: Galaxies, nearby ; X-ray sources Keywords: galaxies: individual (M31) - X-rays: galaxies - X-rays: stars Abstract: We report on Chandra observations of the central region of M31. By combining eight Chandra ACIS-I observations taken between 1999 and 2001, we have identified 204 X-ray sources within the central ∼17'x17' region of M31, with a detection limit of ∼2x1035erg/s. Of these 204 sources, 22 are identified with globular clusters, two with supernova remnants, nine with planetary nebulae, and nine with supersoft sources. By comparing individual images, about 50% of the sources are variable on timescales of months. We also found 13 transients, with light curves showing a variety of shapes. We also extracted the energy spectra of the 20 brightest sources; they can be well fitted by a single power law with a mean photon index of 1.8. The spectral shapes of 12 sources are shown to be variable, suggesting that they went through state changes. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 114 204 CHANDRA ACIS catalog of the central region of M31 table4.dat 58 39 Optical IDs table5.dat 31 77 Cross-Correlation of Chandra and ROSAT Sources
See also: B/chandra : The Chandra Archive Log (CXC, 2002) J/ApJ/578/114 : Chandra HRC source in M31 (Kaaret, 2002) II/144 : Brightest stars in the field of M31 (Berkhuijsen+ 1988) J/A+A/373/63 : M31 second ROSAT PSPC survey (Supper+, 2001) J/A+AS/61/451 : The 37W catalogue of radio sources in M31 (Walterbos+ 1985) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 6 A6 --- [KGP2002] Object identification 8- 13 A6 --- --- [CXOM31] 14- 29 A16 --- CXOM31 Chandra name (JHHMMSS.s+DDMMSS) 31- 32 I2 h RAh Hour of Right Ascension (J2000) 34- 35 I2 min RAm Minute of Right Ascension (J2000) 37- 42 F6.3 s RAs Second of Right Ascension (J2000) 44 A1 --- DE- Sign of the 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- 60 F4.2 arcsec PosErr Positional error 62- 65 I4 ct NCts The net counts 67- 71 F5.2 10-2ct/s CRate The count rate in units of 10-2ct/s 73- 76 F4.2 10-2ct/s e_CRate Error in CRate 78- 82 F5.2 --- HR1 The first hardness ratio (1) 84- 87 F4.2 --- e_HR1 The error in HR1 89- 93 F5.2 --- HR2 The second hardness ratio (2) 95- 98 F4.2 --- e_HR2 The error in HR2 100-104 F5.2 10+30W LXray The 0.3-7keV luminosity in units of 1037erg/s (3) 106-113 A8 --- Notes Additional notes (4)
Note (1): HR1 = (M-S)/(M+S) where S is the 0.3-1.0keV energy band and M is the 1-2keV energy band. Note (2): HR2 = (H-S)/(H+S) where S is the 0.3-1.0keV energy band and H is the 2-7keV energy band. Note (3): Assuming an absorbed power-law model with a photon index of 1.7 and NH=1021cm-2. Note (4): Additional notes: e = Extragalactic objects f = Foreground stars g = Globular Cluster p = Planetary nebula r = ROSAT HRI sources s = Supernova remnant v = Variables sv = Spectral variables t = Transients
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 6 A6 --- [KGP2002] Object identification 9- 24 A16 --- CXOM31 Chandra Name (JHHMMSS.s+DDMMSS) 26- 29 A4 ---- MType Morphological type 31- 42 A12 --- Ident Identification (1) 44- 46 F3.1 arcsec Off Radial offset between the catalogued object and the ACIS source 48- 54 A7 --- Ident2 Second identification (1) 56- 58 F3.1 arcsec Off2 ? Radial offset between the catalogued object and the ACIS source
Note (1): Identifications as follows: mita = Magnier, 1993, Ph.D. thesis, MIT Bo = Battistini et al., 1987A&AS...67..447B Ha94 = Haiman et al., 1994, Cat. II/208 Ford = Ford & Jacoby, 1978ApJ...219..437F, Ciardullo et al., 1989ApJ...339...53 PB = Barmby, 2001, Ph.D. thesis, Harvard Univ. DO80 = d'Odorico et al., 1980A&AS...40...67D MLA = SIMBAD.
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 6 A6 --- [KGP2002] Object Identification 9- 24 A16 --- CXOM31 Chandra name (JHHMMSS.s+DDMMSS) 26- 27 I2 --- [PFJ93] ? ROSAT HRI Identification (Primini et al., 1993ApJ...410..615P 29- 31 F3.1 arcsec Off Radial offset between the HRI and ACIS objects
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Bauer [CDS] 06-Feb-2003
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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