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M31ROSXRAY - ROSAT PSPC M31 Source Catalog |
This catalog is the complete ROSAT PSPC Source List of X-ray
sources found in two surveys of M 31 reported by Supper et al. (1997, 2001).
These papers reported the results of the analysis of the two ROSAT PSPC surveys
of M 31 performed in the summers of 1991 and 1992, respectively.
summer 1992. Supper et al. (2001) compare and combine the results from the two
surveys. In the first survey, 396 X-ray point sources were detected, and an
identical number in the second survey, although this equality is coincidental,
as the source lists are different and contain only 239 sources in common.
Within the approximately 10.7 square degrees field of view of the second
survey, 396 individual X-ray sources were detected, of which 164 sources were
new detections. When combined with the first survey, this resulted in a total
of 560 X-ray sources in the field of M 31. Their (0.1 keV-2.0 keV) fluxes range
from 7 x 10^(-15) to 7.6 x 10^(-12) erg cm^(-2) s^(-1), and of these 560
sources, 55 are tentatively identified with foreground stars, 33 with globular
clusters, 16 with supernova remnants, and 10 with radio sources and galaxies
(including M 32). A comparison with the results of the Einstein M 31 survey
reveals 491 newly detected sources, 11 long-term variable sources, and 7
possible transient sources. Comparing the two ROSAT surveys, Supper et al.
come up with 34 long-term variable sources and 8 transient candidates. For
the M 31 sources, the observed X-ray luminosities range from 4 x 10^(35) to
4 x 10^(38) erg s^(-1). The total (0.1 keV-2.0 keV) luminosity of M 31 is
(3.4 +/- 0.3) x 10^(39) erg s^(-1), distributed approximately equally
between the bulge and disk. Within the bulge region, the luminosity of a
possible diffuse component combined with faint sources below the detection
threshold is (2.0 +/- 0.5) x 10^(38) erg s^(-1). An explanation in
terms of hot gaseous emission leads to a maximum total gas mass of
(1.0 +/- 0.3) x 10^6 solar masses.
The conversion of PSPC count rates into X-ray fluxes depends on the assumed
spectral shape. For M 31-sources, a power law with photon index of -2.0 and
an intervening column density pf 9 x 10^(20) H atoms cm^(-2) may be used,
leading to the conversion factor of 1 ct/ksec = 3.00 x 10^(-14) erg cm^(-2)
s^(-1) in the 0.1-2.0 keV broad band. For foreground stars, the application
of this conversion factor leads to an over-estimate of the fluxes.
2001A&A...373...63S
ROSAT PSPC survey of M31.
Supper R., Hasinger G., Pietsch W., Truemper J., Jain, A., Magnier E.A.,
Lewin W.H.G., and van Paradijs J.,
<Astron. Astrophys. 317, 328 (1997)>
=1997A&A...317..328S
The second ROSAT PSPC survey of M31 and the complete ROSAT PSPC source list.
Supper R., Hasinger G., Lewin W.H.G., Magnier E.A., van Paradijs J.,
Pietsch W., Read A.M., Truemper J.
<Astron. Astrophys. 373, 63 (2001)>
=2001A&A...373...63S
This online catalog was created by the HEASARC in October 2001
based on machine-readable tables obtained from the ADC/CDS data centers
(their catalog J/A+A/373/63, and table table6.dat).
Source_Flag
Source classification flag with the following meanings:
a: Foreground star
b: Galaxy
c: Supersoft source candidate
d: Globular cluster
e: SNR
f: Bulge source
v: Variable source (ref. Table2, 3 and footnote in Sect. 4.1.1)
u: Source with uncertain count rate
Notice that the HEASARC has changed the last three symbols (f, v, and u) from
their non-alphabetic values (*, ~, and +, respectively) in the original
catalog.
Name
The M 31 X-ray source name derived from the standard prefix for ROSAT
X-ray sources of 'RX' and a numeric string based on the J2000 positional
coordinates.
Einstein_Flag
A flag that is set to 'Y' to indicate that the source was
correlated with an Einstein X-ray source. Notice that the HEASARC has changed
this value from the non-alphabetic value of '*' in the original catalog.
S2_Number
The source number in the Second Survey (S II) of M31 as given
in Table 5 of Supper et al. (2001).
S1_Number
The source number in the First Survey (S I) of M31 as given
in Table 5 of Supper et al. (1997).
Survey_Flag
This is a data identification marker flag with possible
values of '+', '-', or ' ' corresponding to the following rubric:
'+' = Source was seen in both surveys and listed data are
from the first survey.
'-' = Source was seen in both surveys and listed data are
from the second survey.
blank = Source was *only* seen in one of the surveys (the one with the
non-null survey number), and the listed data are from it
RA
The Right Ascension of the X-ray source in the selected equinox. This
was given in J2000 coordinates to a precision of 0.1 seconds of time in the
original catalog.
Dec
The Declination of the X-ray source in the selected equinox. This
was given in J2000 coordinates to a precision of 1 arcsecond in the
original catalog.
LII
The Galactic Longitude of the X-ray source.
BII
The Galactic Latitude of the X-ray source.
Error_Radius
The 1-sigma uncertainty in the source position, in arcseconds.
The calculation of this positional uncertainty is based on the maximum
likelihood algorithm and incorporates the effects of statistical errors
depending on the number of source counts, together with the blur radius of
the point spread function (PSF) at the off-axis angle and the mean photon
energy of the source. A minimum threshold of 5 arcseconds is also set to
account for a systematic positional error.
Quality_Flag
A classification of the quality of the detection.This is
differently defined for sources in the two surveys, notice.
For sources found in the first survey, the classification parameter is as
follows: class 1 identifies sources detected in the central region of the
PSPC with off-axis angles <= 20 arcminutes, class 2 defines locations of
sources found between 20 and 40 arcminutes, and class 3 contains sources with
off-axis angles > 40 arcminutes. As mentioned in Sect. 2 of Supper et al.
(1997), the source position was derived from the pointing in which it appears
at the lowest off-axis angle, i.e., with the best class (though not under a
PSPC rib). For sources in class 2 and especially class 3, any upper limit in
the listed count rates can even be an underestimation due to the wider PSF
and the therefore higher possibility of rib influencies.
For sources found in the second survey, the listed classification parameter
is defined class 1 for sources detected in the inner PSPC region (20 arcminutes
radius) and class 4 for sources outside this region.
The caveats for the first survey source catalogue mentioned in Supper et al.
(1997) are still valid whenever these sources are not replaced by second
survey detections.
Max_Likelihood
The highest likelihood of existence found in any of the five
energy bands as computed with the maximum likelihood method.
Rate_B_Flag
A flag that is set to '<' to indicate an upper limit on
the broad-band count rate.
Rate_B
The broad-band (0.1-2.0 keV) count rate in counts per second (ct/s).
This was converted by the HEASARC from the counts per kilosecond unit given in
the original catalog. Because some faint sources were not detected in all
energy bands (i.e., these sources had a likelihood below the threshold value
of 10 in one or more energy bands), in such cases 1-sigma upper limits to
the count rates are presented. These upper limits are computed from the
1-sigma fluctuations (Poissonian statistics) of the background counts at the
source position and are indicated by the corresponding rate flag parameter
(rate_b_flag in this case) having a value of <.
Rate_B_Error
The statistical 1-sigma Error in the broad-band count rate,
in counts per second (ct/s). This was converted by the HEASARC from the counts
per kilosecond unit given in the original catalog. Notice that the listed
count rate errors are only the statistical errors, whereas the systematical
errors are expected to be less than +/- 15%.
Rate_S_Flag
A flag that is set to '<' to indicate an upper limit on
the soft-band count rate.
Rate_S
The soft-band (0.1-0.4 keV) count rate in counts per second (ct/s).
This was converted by the HEASARC from the counts per kilosecond unit given in
the original catalog. Because some faint sources were not detected in all
energy bands (i.e., these sources had a likelihood below the threshold value
of 10 in one or more energy bands), in such cases 1-sigma upper limits to
the count rates are presented. These upper limits are computed from the
1-sigma fluctuations (Poissonian statistics) of the background counts at the
source position and are indicated by the corresponding rate flag parameter
(rate_s_flag in this case) having a value of <.
Rate_S_Error
The statistical 1-sigma Error in the soft-band count rate,
in counts per second (ct/s). This was converted by the HEASARC from the counts
per kilosecond unit given in the original catalog. Notice that the listed
count rate errors are only the statistical errors, whereas the systematical
errors are expected to be less than +/- 15%.
Rate_H_Flag
A flag that is set to '<' to indicate an upper limit on
the hard-band count rate.
Rate_H
The hard-band (0.5-2.0 keV) count rate in counts per second (ct/s).
This was converted by the HEASARC from the counts per kilosecond unit given in
the original catalog. Because some faint sources were not detected in all
energy bands (i.e., these sources had a likelihood below the threshold value
of 10 in one or more energy bands), in such cases 1-sigma upper limits to
the count rates are presented. These upper limits are computed from the
1-sigma fluctuations (Poissonian statistics) of the background counts at the
source position and are indicated by the corresponding rate flag parameter
(rate_h_flag in this case) having a value of <.
Rate_H_Error
The statistical 1-sigma Error in the hard-band count rate,
in counts per second (ct/s). This was converted by the HEASARC from the counts
per kilosecond unit given in the original catalog. Notice that the listed
count rate errors are only the statistical errors, whereas the systematical
errors are expected to be less than +/- 15%.
Rate_H1_Flag
A flag that is set to '<' to indicate an upper limit on
the 0.5-0.9 keV band count rate.
Rate_H1
The Hard1-band (0.5-0.9 keV) count rate in counts per second (ct/s).
This was converted by the HEASARC from the counts per kilosecond unit given in
the original catalog. Because some faint sources were not detected in all
energy bands (i.e., these sources had a likelihood below the threshold value
of 10 in one or more energy bands), in such cases 1-sigma upper limits to
the count rates are presented. These upper limits are computed from the
1-sigma fluctuations (Poissonian statistics) of the background counts at the
source position and are indicated by the corresponding rate flag parameter
(rate_h1_flag in this case) having a value of <.
Rate_H1_Error
The statistical 1-sigma Error in the 0.5-0.9 keV band count
rate, in counts per second (ct/s). This was converted by the HEASARC from the
counts per kilosecond unit given in the original catalog. Notice that the
listed count rate errors are only the statistical errors, whereas the
systematic errors are expected to be less than +/- 15%.
Rate_H2_Flag
A flag that is set to '<' to indicate an upper limit on
the 0.9-2.0 keV count rate.
Rate_H2
The hard2-band (0.9-2.0 keV) count rate in counts per second (ct/s).
This was converted by the HEASARC from the counts per kilosecond unit given in
the original catalog. Because some faint sources were not detected in all
energy bands (i.e., these sources had a likelihood below the threshold value
of 10 in one or more energy bands), in such cases 1-sigma upper limits to
the count rates are presented. These upper limits are computed from the
1-sigma fluctuations (Poissonian statistics) of the background counts at the
source position and are indicated by the corresponding rate flag parameter
(rate_h2_flag in this case) having a value of <.
Rate_H2_Error
The statistical 1-sigma Error in the 0.9-2.0 keV band count
rate, in counts per second (ct/s). This was converted by the HEASARC from the
counts per kilosecond unit given in the original catalog. Notice that the
listed count rate errors are only the statistical errors, whereas the
systematic errors are expected to be less than +/- 15%.
Class
The HEASARC Browse Object Classification, derived in this case
from the value of the source_flag parameter. Only a small fraction of the
sources in this catalog have classification information.
Questions regarding the M31ROSXRAY database table can be addressed to the
HEASARC User Hotline.
If you have any problems, please consult the help
page or mail ledas-help@star.le.ac.uk
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