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ARIEL3A - 3rd Ariel-V SSI Catalog

HEASARC
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Overview

The 3rd Ariel-V SSI Catalog contains a list of X-ray sources detected by the University of Leicester's Sky Survey Instrument (SSI) on the Ariel-V satellite, and published (in 2 papers) as the Ariel-V (3A) Catalog: Warwick et al. 1981, MNRAS, 197, 865 (the low galactic latitude sources) and McHardy et al. 1981, MNRAS, 197, 893 (the high galactic latitude sources). The catalog is based on observations extending over a 5.5 year period from 1974 October until 1980 March. The SSI had a field of view of 0.75 by 10.6 degrees (FWHM) and had an energy range from 2 to 18 keV. A detailed description of the SSI is given by Villa et al. 1976, MNRAS, 176, 609. For a more detailed discussion of how the 3A Catalog was created, please refer to the Warwick et al. (1981) and McHardy et al. (1981) papers.

Catalog Bibcode

1981MNRAS.197..865W

References

McHardy, I.M., et al. 1981, MNRAS, 197, 893

Warwick, R.S., et al. 1981, MNRAS, 197, 865

Provenance

This online catalog was created by the HEASARC in March 2003 based on the merger of two original tables originally obtained from the ADC website (ftp://legacy.gsfc.nasa.gov/heasarc/dbase/misc_files/ariel3a/hilat.dat and ftp://legacy.gsfc.nasa.gov/heasarc/dbase/misc_files/ariel3a/lowlat.dat).

HEASARC Implementation

One source (3A0327+348, GK Per) is listed in both Warwick et al. 1981, MNRAS, 197, 865 (the low galactic latitude sources), and in McHardy et al. 1981, MNRAS, 197, 893 (the high galactic latitude sources). To avoid having a duplicate entry in this HEASARC table, the Warwick et al. entry for this source has been deleted. The HEASARC also added flux and flux_error parameters, and flux_mcrab and flux_mcrab_error parameters, which were calculated using conversion factors as described in the help descriptions for these parameters. The HEASARC also added the parameter min_count_rate_limit, based on information from the published catalog but apparently missing from the ADC version.

Parameters

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 ftp://legacy.gsfc.nasa.gov/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 ftp://legacy.gsfc.nasa.gov/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/cm^2/s. This was calculated by the HEASARC using the conversion formula given in the published papers: 5.3 x 10^-11 erg/cm^2/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/cm^2/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 ftp://legacy.gsfc.nasa.gov/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).


Contact Person

Questions regarding the ARIEL3A database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 8-Nov-2004