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ARIEL3A - 3rd Ariel-V SSI Catalog |
HEASARC Archive |
McHardy, I.M., et al. 1981, MNRAS, 197, 893 Warwick, R.S., et al. 1981, MNRAS, 197, 865
Name
The 3rd Ariel (3A) catalog designation of the X-ray source.
This designation consists of a "3A" followed by the celestial coordinates
of the source position (1950 equatorial coordinates).
Alt_Names
Alternative names for the X-ray source. Up to three other names
are given for the X-ray source. These designations are generally derived
from observations by the following satellites:
A Ariel V; both earlier SSI and rotation collimator observations.
2A Ariel V; see Cooke et al. (1978, MNRAS, 182, 489).
H HEAO-1; A2 and A3 experiments.
1E Einstein observatory
MX OSO-7 or SAS-3; see Markert et al. (1976, ApJ, 206, 265).
4U Uhuru; see Forman et al. (1978, ApJS, 38, 357).
In addition, common names (e.g. Sco X-1, Cen X-3) and source names obtained
from earlier, mainly rocket, observations derived from the galactic
coordinates of the source, e.g. GX 301-2, are listed in this field. References
to these names may be found in Forman et al. (1978) or Bradt et al. (1979),
respectively. Otherwise, a reference identification enclosed in brackets
may be listed here or in the Comments field; the key to these references
is only available in the published version of the 2 papers that
comprise the 3A Catalog (q.v.). The references are all listed in the file
https://heasarc.gsfc.nasa.gov/FTP/heasarc/dbase/misc_files/ariel3a/refs.dat,
but, unfortunately, under a different (alphabetically coded) scheme.
RA
The right ascension of the position of maximum probability density for
the X-ray source location in the selected equinox. This was given in degrees
in 1950.0 equinox to a precision of 0.01 degrees in the original table.
Dec
The declination of the position of maximum probability density for
the X-ray source location in the selected equinox. This was given in degrees
in 1950.0 equinox to a precision of 0.01 degrees in the original table.
LII
The Galactic longitude of the position of maximum probability density for
the X-ray source location in the selected equinox. This was given in degrees
to a precision of 0.01 degrees in the original table.
BII
The Galactic latitude of the position of maximum probability density for
the X-ray source location in the selected equinox. This was given in degrees
to a precision of 0.01 degrees in the original table.
RA1
The right ascension of an error box corner, i.e., one of the four
corners of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
Dec1
The declination of an error box corner, i.e., one of the four corners
of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
RA2
The right ascension of an error box corner, i.e., one of the four
corners of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
Dec2
The declination of an error box corner, i.e., one of the four corners
of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
RA3
The right ascension of an error box corner, i.e., one of the four
corners of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
Dec3
The declination of an error box corner, i.e., one of the four corners
of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
RA4
The right ascension of an error box corner, i.e., one of the four
corners of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
Dec4
The declination of an error box corner, i.e., one of the four corners
of a rectangle enclosing an elliptical approximation to a 90%
confidence contour for the source location, in decimal degrees (equinox 1950
in the Browse CLI environment; equinox 2000 in the W3Browse environment).
The error box coordinates are listed only for sources for which the SSI
observations provide information of a precision which is comparable to, or
better than, previously reported X-ray measurements (above 2 keV). These are
sources with a position code of "3A".
Error_Area
The area within the 90% confidence contour, in square degrees.
Position_Code
A position code indicating in what manner the position of
the X-ray source was obtained. Thus, the source positions are not limited to
those derived from SSI observations. Accurate X-ray positions (notably from
SAS-3 and HEAO-1 satellite observations) as well as optical and radio positions
are available for many of the bright, low latitude X-ray sources. The position
codes are as follows:
3A Position based on SSI observations
X-RAY Position obtained from other published X-ray observations
OPT Position obtained from published observations of the optical
counterpart of the X-ray source.
RAD Position obtained from published observations of the radio
counterpart of the X-ray source.
References to these published source positions may be found in the Bradt et
al. (1979) X-Ray Source Catalog, unless a reference identification enclosed
in brackets follows a "POS" flag in the Comments field; the key to these
references is only available in the published version of the 2 papers that
comprise the 3A Catalog (q.v.). The references are all listed in the file
https://heasarc.gsfc.nasa.gov/FTP/heasarc/dbase/misc_files/ariel3a/refs.dat,
but, unfortunately, under a different (alphabetically coded) scheme.
Count_Rate
The average count rate for the X-ray source, in SSI count s-1.
All count rate determinations and variability code assignments were made from
summed-orbit records.
Count_Rate_Error
The one-sigma error in the average count rate for the
X-ray source, in SSI count s-1.
Flux
The average flux for the X-ray source in the 2 - 6 keV band, in
erg/cm2/s. This was calculated by the HEASARC using the conversion formula
given in the published papers: 5.3 x 10-11 erg/cm2/s = 1 SSI count/s.
This conversion factor was computed assuming a Crab-like spectrum, and
has an uncertainty of ~15%.
Flux_Error
The one-sigma error in the average flux for the X-ray source in
the 2 - 6 keV band, in erg/cm2/s.
Flux_mCrab
The average flux for the X-ray source in the 2 - 6 keV band, in
milliCrabs. This was calculated by the HEASARC using the conversion formula:
2.4814 milliCrab = 1 SSI count/s. The conversion factor was chosen so that
the flux of the source 3A0531+219 associated with the Crab is 1000 milliCrabs.
Flux_mCrab_Error
The one-sigma error in the average flux for the X-ray
source in the 2 - 6 keV band, in milliCrabs.
Min_Count_Rate_Limit
This flag indicates that the minimum count rate is actually an upper limit.
Min_Count_Rate
The minimum count rate for the X-ray source, in SSI count s-1. All count
rate determinations and variability code assignments were made from
summed-orbit records.
Min_Count_Rate_Error
The error in the minimum count rate for the X-ray source, in SSI count s-1.
Max_Count_Rate
The maximum count rate for the X-ray source, in SSI count s-1. All count
rate determinations and variability code assignments were made from
summed-orbit records.
Max_Count_Rate_Error
The error in the maximum count rate for the X-ray source, in SSI count s-1.
Variability_Code
A coded flag with information on the variability of
the X-ray source as follows:
S Steady: The average count rate is the weighted mean value from all
observations. The minimum and maximum count rate fields
contain no data.
I Irregular: The average, minimum, and maximum count rate values are
listed. These are sources which the SSI determined to be
periodic (e.g. HER X-1). This class also includes those
sources seen to exhibit flaring where emission was also
observed by the SSI outside of the flares (e.g. 3A 1102+385
= MKN 421) and those with a formal probability <1% that the
X-ray light curve could result from steady X-ray emission.
T Transient: Only the maximum count rate is listed. This class includes
sources that would generally not be detected by SSI
observations because of their short duration (<= 50 days).
Such outbursts often exhibit dramatic flux increases (see
Kaluzienski 1977, PhD thesis or Cominsky et al. 1978, ApJ,
224, 46), some of which are recurrent (e.g., A0535+26). For
a transient source, the SSI did not detect any X-ray emission
except for that which was a result of the outburst.
Optical_ID
The suggested identification of the X-ray source. The method
by which these were obtained in the high latitude survey is described in
section 5 of McHardy et al. (1981). The sources in the high latitude survey
part of this catalog also contain an identification code within this parameter
field which expresses the level of confidence in the identification as follows:
**** Almost certain: There are three categories of evidence which support
the identification. They are as follows: (a) correlated X-ray/optical
or X-ray/radio variability; (b) the X-ray emission has been spatially
resolved, e.g. sources proposed as clusters of galaxies; (c) the object
is inside a very precise (dimension approx. few arc seconds) X-Ray
error box. More than one category of evidence may support any given
identification.
*** Very likely: the source is contained within a very small (dimensions
<= 1 arcmin) error box.
** Probable: the source is contained within or very close to a small
(<= 0.1 square deg) 3A error box or inside a larger 3A error box and
has supporting evidence.
* Possible: the source identification is a result of positional
coincidence only.
The supporting evidence may be referenced in the Comments field.
Comments
This field mainly contains additional information which is often
followed by a reference identification in brackets. References for the
identification and position code fields are listed in a similar fashion.
The latter is always indicated by a "POS" flag. The sources in the low
latitude survey may contain references to earlier papers based on SSI
observations of sources in the catalog; these are indicted by a "SSI" flag
followed by the reference identification in brackets. The key to these
references is only available in the published version of the 2 papers that
comprise the 3A Catalog (q.v.). The references are all listed in the file
https://heasarc.gsfc.nasa.gov/FTP/heasarc/dbase/misc_files/ariel3a/refs.dat,
but, unfortunately, under a different (alphabetically coded) scheme.
Also listed is any periodic behavior in the X-ray emission from the source. Note that "Seyfert" indicates a "Seyfert type I" galaxy, and "Hexelg" refers to any other type of high extinction emission line galaxy. It is probable that almost all of the latter are, in fact, "Seyfert type II" galaxies. See the 3A published papers (Warwick et al. 1981, McHardy et al. 1981) for additional information concerning this field.
Class
The HEASARC Browse object classification (not yet populated).
