J/ApJ/609/735 M31 Chandra X-ray sources (Williams+, 2004)
A synoptic X-ray study of M31 with the Chandra high resolution camera.
Williams B.F., Garcia M.R., Kong A.K.H., Primini F.A., King A.R.,
Di Stefano R., Murray S.S.
<Astrophys. J., 609, 735-754 (2004)>
=2004ApJ...609..735W 2004ApJ...609..735W
ADC_Keywords: Galaxies, nearby ; X-ray sources
Keywords: galaxies: individual (M31) - galaxies: spiral - X-rays: binaries -
X-rays: galaxies - X-rays: general
Abstract:
We have obtained 17 epochs of Chandra High Resolution Camera (HRC)
snapshot images, each covering most of the M31 disk. The data cover a
total baseline of ∼2.5yr and contain a mean effective exposure of
17ks. We have measured the mean fluxes and long-term light curves for
166 objects detected in these data.
Description:
The data for this project are originally part of a survey program to
look for X-ray transients in M31. Nearly every month from 1999
November to 2001 February, Chandra took HRC-I images of five fields
covering most of M31. Observations were then made every few months
until 2002 June.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 49 81 Summary of Chandra HRC-I observations
table2.dat 99 166 Luminosities, variability, other detections,
references and object types for the X-ray sources
notes.dat 80 31 Notes and references
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See also:
B/chandra : The Chandra Archive Log (CXC, 2002)
J/ApJ/577/738 : M31 Chandra X-ray point sources (Kong+, 2002)
J/ApJ/578/114 : Chandra HRC source in M31 (Kaaret, 2002)
J/ApJ/610/247 : M31 supersoft and quasi-soft X-ray sources (Di Stefano+, 2004)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ObsID Observation identification number
6- 15 A10 "YYYY/MM/DD" ObsDate Date of observation
17- 18 I2 --- Epoch Observation epoch number
20 I1 h RAh Hour of Right Ascension (J2000)
22- 23 I2 min RAm Minute of Right Ascension (J2000)
25- 29 F5.2 s RAs Second of Right Ascension (J2000)
30 A1 --- DE- Sign of the Declination (J2000)
31- 32 I2 deg DEd Degree of Declination (J2000)
34- 35 I2 arcmin DEm Arcminute of Declination (J2000)
37- 40 F4.1 arcsec DEs Arcsecond of Declination (J2000)
42- 49 F8.3 s ExpTime Exposure time
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- [KGP2002] Object identification (1)
8 I1 h RAh Hour of Right Ascension (J2000)
10- 11 I2 min RAm Minute of Right Ascension (J2000)
13- 17 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 33 I4 ct Cts Total counts in the detection
35- 39 F5.1 --- S/N Wavdetect measured signal-to-noise
41- 45 F5.1 10+29W Lum Mean luminosity in units of 10+36erg/s (2)
47- 49 F3.1 10+29W e_Lum Uncertainty in Lum
51- 57 F7.3 --- chi2 The χ2ν of the fit (3)
59- 88 A30 --- CP Counterpart found at other wavelengths
or X-ray surveys (4)
90- 92 A3 --- Rem Indicates a note detailed in files notes.dat
94- 98 A5 --- Type Object type (5)
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Note (1): Identical sources have the same names in Kong et al. (2002, Cat.
J/ApJ/577/738) and Di Stefano et al. (2004, Cat. J/ApJ/610/247).
The prefixes are:
- r1 designates objects in a square region 2'x2' centered on the nucleus;
- r2 designates objects outside of r1 but within a square region 8'x8'
centered on the nucleus;
- r3 designates objects outside of r2 but within a square region 23'x23'
centered on the nucleus;
- n1 designates objects outside of r3, north of the nucleus but south
of DE=42:01:00 (J2000);
- n2 designates objects north of DE=42:01:00 (J2000);
- s1 designates objects outside of r3, south of the nucleus but north
of DE=40:31:22 (J2000);
- s2 designates objects south of DE=40:31:22 (J2000).
New objects within these regions are numbered consecutively starting
from the highest published number in either Kong et al. (2002, Cat.
J/ApJ/577/738) or Di Stefano et al. (2004, Cat. J/ApJ/610/247).
The IAU sanctioned names for the sources can be formulated by applying
the right ascension and declination to the prefix CXOM31. For example,
the proper name of s1-74 is CXOM31 J003956.3+404100.
Note (2): Over all epochs. This luminosity was calculated by multiplying the
measured flux by the conversion factor discussed in Section 2.3.
Note (3): Resulting from a fit of the measured counting rate to a constant
source at the mean rate. A value greater than 1.47 indicates that
the source has a 90% chance of being variable.
Note (4): If the object was detected in previous X-ray surveys as well as in
other wavelengths, the optical (or, in one case, radio) counterpart
is listed. If the object has no known counterpart outside of the
X-ray band, the earliest detection is listed as the X-ray
counterpart. With the exception of the "mita" prefix, counterpart
names are IAU names taken from the Simbad database
(http://simbad.u-strasbg.fr/). X-ray sources with no previous
detections and no optical counterparts are labeled "new".
Note (5): Flag on [KGP2002], with the following meaning:
* = The source has a stellar counterpart.
X = The source has no optical counterpart, but a previous X-ray
detection is listed.
GC = The X-ray source lies in a known M31 globular cluster.
SNR = The X-ray source position is coincident with a known M31
supernova remnant.
PN = The X-ray source position is coincident with a known, unconfirmed
M31 planetary nebula. These may be misidentified SNR.
BLL = The X-ray source position is coincident with a BL Lac candidate.
Radio = The source has also been detected in the radio.
? = The source has a counterpart of unknown nature.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Rem Reference to the note
5- 80 A76 --- Text Note and reference
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 28-Jul-2005