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A4: Help

A4 - HEAO 1 A-4 Catalog of High-Energy X-Ray Sources


Overview

The HEAO 1 A-4 Catalog of High-Energy X-ray Sources represents results from an all-sky survey carried out at high X-ray energies (13-180 keV) from August 1977 until January 1979 using data obtained with the UCSD/MIT Hard X-Ray and Low-Energy Gamma-Ray Instrument on the HEAO 1 satellite. Quantitative results from a model-dependent fitting procedure are given in the form of fitted count rates in four broad energy bands for about 70 sources. The survey is complete, except in regions of source confusion, down to an intensity level of about 1/75 of the Crab Nebula in the 13-80 keV energy band. Forty-four sources were detected in the 40-80 keV energy band, and 14 in the 80-180 keV band. Most of the sources are galactic; seven are extragalactic.

Catalog Bibcode

1984ApJS...54..581L

References

The instrumentation, observations, and analysis techniques used to produce the A-4 catalog are described in detail in "The HEAO 1 A-4 Catalog of High-Energy X-Ray Sources", A.M.Levine et al., Ap.J.Suppl., 54:581-617, 1984 April.

Description

One of the primary goals of the HEAO 1 mission was to survey the sky at high X-ray energies (E>10 keV) with the UCSD/MIT Hard X-Ray and Low-Energy Gamma-Ray instrument (A-4). Over 16 months were spent carrying out this survey.

The A-4 catalog database includes those sources which were clearly evident in the sky-survey data (i.e., detected at a level of statistical significance greater than approximately 6 sigma), as well as sources which were of particular interest but were not detected at a 6-sigma significance level. For each scan of a source, the fitted count rates (and their associated 1 sigma errors) are listed for the various energy bands. The entire set of data for a source, from the whole mission, was also fitted, to produce "All Data" count rates and errors for each energy band. Most, but not all, of the sources in the catalog were scanned three times during the mission.

In the original catalog, some count rates were listed as "NF" (negative flux); this indicates that the corresponding estimated intensity was negative. In such cases the corresponding source position was removed from the model for that broad energy band, and the intensities of the other sources were reestimated. In the A4 database, the "NF" notation has not been used; instead, count rates with associated negative fluxes have been given values of zero.

As mentioned, some of the sources were scanned only twice, and thus no data was present for a third scan. The database system conventions for "NO DATA" were used for such cases; that is, the scan 3 count rate, flux, and error values are listed as -1.2E-34, and the scan start and end dates are listed as 31 December 1999.


Parameters

Alla_Count_Rate
Fitted count rate for the source, taking into account all of the data from the mission, for channel A (13 to 25 keV). `AllA count rate error` is the associated error.

Alla_Count_Rate_Error
All data 13-25 keV count rate error

Alla_Flux
The energy flux corresponding to count rate for the source, taking into account all of the data from the mission, for channel A (13 to 25 keV), in ergs cm**-2 s**-1 keV**-1. `AllA flux error` is the associated error.

Alla_Flux_Error
13-25 keV flux error

Allb_Count_Rate
Fitted count rate for the source, taking into account all of the data from the mission, for channel B (25 to 40 keV). `AllB count rate error` is the associated error.

Allb_Count_Rate_Error
All data 25-40 keV count rate error

Allb_Flux
The energy flux corresponding to count rate for the source, taking into account all of the data from the mission, for channel B (25 to 40 keV), in ergs cm**-2 s**-1 keV**-1. `AllB flux error` is the associated error.

Allb_Flux_Error
25-40 keV flux error

Allc_Count_Rate
Fitted count rate for the source, taking into account all of the data from the mission, for channel C (40 to 80 keV). `AllC count rate error` is the associated error.

Allc_Count_Rate_Error
All data 40-80 keV count rate error

Allc_Flux
The energy flux corresponding to count rate for the source, taking into account all of the data from the mission, for channel C (40 to 80 keV), in ergs cm**-2 s**-1 keV**-1. `AllC flux error` is the associated error.

Allc_Flux_Error
40-80 keV flux error

Allcont_Count_Rate
Contamination count rate; an estimate of the magnitude of the contributions from other sources to the raw count rate data for the source, taking into account all of the data from the mission, given for channel A (13 to 25 keV).

Alld_Count_Rate
Fitted count rate for the source, taking into account all of the data from the mission, for channel D (80 to 180 keV). `AllD count rate error` is the associated error.

Alld_Count_Rate_Error
All data 80-180 keV count rate error

Alld_Flux
The energy flux corresponding to count rate for the source, taking into account all of the data from the mission, for channel D (80 to 180 keV), in ergs cm**-2 s**-1 keV**-1. `AllD flux error` is the associated error.

Alld_Flux_Error
80-180 keV flux error

Alt_Name
Alternate name of source, if present.

BII
Galactic latitude

Count_Rate
Fitted count rate for the source, taking into account all of the data from the mission, for channels A+B+C (13 to 80 keV). `Count rate error` is the associated error.

Count_Rate_Error
All data 13-80 keV count rate error

Dec
The declination, in degrees, of the celestial position which was used in the fitting procedure to estimate count rates for the source.

Elat
The ecliptic latitude corresponding to the given right ascension and declination.

Elong
The ecliptic longitude corresponding to the given right ascension and declination.

LII
Galactic Longitude

Name
The name of the source. The numerical names, given without prefixes because no previously unknown sources are included in the catalog, are based on celestial position.

Object_Codes
The letters listed indicate previous X-ray catalog designators or prefixes, or indicate the satellite which was used in the observations leading to an identification of the object. The codes are summarized as follows:

     U = Uhuru;  M = OSO 7;  A = Ariel 5;  S = SAS 3;  H = HEAO 1;
     E = Einstein Observatory;  C = Copernicus.
  

Opt_Radio_Name
The name of the associated optical or radio counterpart of the X-ray source, if present.

RA
The right ascension, in degrees, of the celestial position which was used in the fitting procedure to estimate count rates for the source.

S1_End
The end time of the first scan, listed as `year/daynumber hr:min`.

S1_Start
The start time of the first scan (the time at which the source came, during spacecraft spinning, within +/-10 degrees of the detector view axis), listed as `year/daynumber hr:min`.

S1a_Count_Rate
Fitted count rate for first scan, channel A (13 to 25 keV). The associated error is `S1A count rate error`.

S1a_Count_Rate_Error
Scan 1, 13-25 keV count rate error

S1abc_Count_Rate
Fitted count rate for first scan, channels A+B+C (13 to 80 keV). The associated error is `S1ABC count rate error`.

S1abc_Count_Rate_Error
Scan 1, 13-80 keV count rate error

S1b_Count_Rate
Fitted count rate for first scan, channel B (25 to 40 keV). The associated error is `S1B count rate error`.

S1b_Count_Rate_Error
Scan 1, 25-40 keV count rate error

S1c_Count_Rate
Fitted count rate for first scan, channel C (40 to 80 keV). The associated error is `S1C count rate error`.

S1c_Count_Rate_Error
Scan 1, 40-80 keV count rate error

S1cont_Count_Rate
Contamination count rate; an estimate of the magnitude of the contributions from other sources to the raw count rate data, given for channel A (13 to 25 keV).

S1d_Count_Rate
Fitted count rate for first scan, channel D (80 to 180 keV). The associated error is `S1D count rate error`.

S1d_Count_Rate_Error
Scan 1, 80-180 keV count rate error

S2_End
The end time of the second scan, listed as `year/daynumber hr:min`.

S2_Start
The start time of the second scan (the time at which the source came, during spacecraft spinning, within +/-10 degrees of the detector view axis), listed as `year/daynumber hr:min`.

S2a_Count_Rate
Fitted count rate for second scan, channel A (13 to 25 keV). The associated error is `S2A count rate error`.

S2a_Count_Rate_Error
Scan 2, 13-25 keV count rate error

S2abc_Count_Rate
Fitted count rate for second scan, channels A+B+C (13 to 80 keV). The associated error is `S2ABC count rate error`.

S2abc_Count_Rate_Error
Scan 2, 13-80 keV count rate error

S2b_Count_Rate
Fitted count rate for second scan, channel B (25 to 40 keV). The associated error is `S2B count rate error`.

S2b_Count_Rate_Error
Scan 2, 25-40 keV count rate error

S2c_Count_Rate
Fitted count rate for second scan, channel C (40 to 80 keV). The associated error is `S2C count rate error`.

S2c_Count_Rate_Error
Scan 2, 40-80 keV count rate error

S2cont_Count_Rate
Contamination count rate; an estimate of the magnitude of the contributions from other sources to the raw count rate data, given for channel A (13 to 25 keV).

S2d_Count_Rate
Fitted count rate for second scan, channel D (80 to 180 keV). The associated error is `S2D count rate error`.

S2d_Count_Rate_Error
Scan 2, 80-180 keV count rate error

S3_End
The end time of the third scan, listed as `year/daynumber hr:min`.

S3_Start
The start time of the third scan (the time at which the source came, during spacecraft spinning, within +/-10 degrees of the detector view axis), listed as `year/daynumber hr:min`.

S3a_Count_Rate
Fitted count rate for third scan, channel A (13 to 25 keV). The associated error is `S3A count rate error`.

S3a_Count_Rate_Error
Scan 3, 13-25 keV count rate error

S3abc_Count_Rate
Fitted count rate for third scan, channels A+B+C (13 to 80 keV). The associated error is `S3ABC count rate error`.

S3abc_Count_Rate_Error
Scan 3, 13-80 keV count rate error

S3b_Count_Rate
Fitted count rate for third scan, channel B (25 to 40 keV). The associated error is `S3B count rate error`.

S3b_Count_Rate_Error
Scan 3, 25-40 keV count rate error

S3c_Count_Rate
Fitted count rate for third scan, channel C (40 to 80 keV). The associated error is `S3C count rate error`.

S3c_Count_Rate_Error
Scan 3, 40-80 keV count rate error

S3cont_Count_Rate
Contamination count rate; an estimate of the magnitude of the contributions from other sources to the raw count rate data, given for channel A (13 to 25 keV).

S3d_Count_Rate
Fitted count rate for third scan, channel D (80 to 180 keV). The associated error is `S3D count rate error`.

S3d_Count_Rate_Error
Scan 3, 80-180 keV count rate error


Contact Person

Questions regarding the A4 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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