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RASSFSC - ROSAT All-Sky Survey: Faint Sources

HEASARC
Archive

Overview

The ROSAT All-Sky Survey Faint Source Catalog (RASS-FSC) was first released by the Max-Planck-Institut fuer extraterrestrische Physik, Garching group (voges et al. 2000) in May 2000. It is derived from the All-Sky Survey performed during the ROSAT mission using the Position-Sensitive Proportional Counter (PSPC) in the energy range 0.1 to 2.4 keV. Over one hundred thousand (105,924 to be exact) sources are catalogued herein, representing the faint extension of the RASS Bright Source Catalog (RASS-BSC, cf. IAU Circular 6420 and Voges et al. 1999, A&A, 349, 389: this is also available at the HEASARC as the RASSBSC database). The sources in this catalog have a detection likelihood of at least seven, and contain at least six source photons. The likelihood L of source detection is defined as L = -ln (1 - P), where P = the probability of source detection. For each source, the ROSAT name, position and positional error, the source count rate and error, the background count rate, the exposure time, the date of observation, two hardness ratios and their associated errors, the source extent and the extent likelihood, and the likelihood of source detection are given, inter alia.

Catalog Bibcode

<IX/29/rass_fsc.dat>

References

The ROSAT All-Sky Survey Faint Source Catalog (RASS-FSC or 1RXS-F), W. Voges, B. Aschenbach, Th. Boller, H. Braeuninger, U. Briel, W. Burkert, K. Dennerl, J. Englhauser, R. Gruber, F. Haberl, G. Hartner, G. Hasinger, E. Pfeffermann, W. Pietsch, P. Predehl, J.H.M.M. Schmitt, J. Truemper, and H.-U. Zimmermann (Max-Planck-Institut fuer extraterrestrische Physik, Garching), May 26 2000 release. More information on the ROSAT All-Sky Survey Faint Source Catalog can be found at the URL http://www.xray.mpe.mpg.de/rosat/survey/rass-fsc/

Provenance

This HEASARC database was created in July 2000 based on the May 26 2000 release of the ROSAT All-Sky Survey Faint Source Catalog obtained from the Max-Planck-Institut fuer extraterrestrische Physik, Garching Website: http://www.xray.mpe.mpg.de/rosat/survey/rass-fsc/

Parameters

Name
The source name in the ROSAT All-Sky Survey Catalog.

RA
The right ascension of the X-ray source in the selected equinox: notice that this was provided in equinox 2000 in the originating table.

Dec
The declination of the X-ray source in the selected equinox: notice that this was provided in equinox 2000 in the originating table.

LII
Galactic Longitude.

BII
Galactic Latitude.

Positional_Error
The total positional error in arcseconds; this is the combined 1-sigma statistical and systematic error, where a systematic error of 6 arcsec has been adopted. A value of 0 means that this information is not available.

Screening_Flag
The flags from the visual and automatic screening, in the order NPEDM, according to the following scheme, where the possible values are 'T' for True, 'F' or '_' for False, and '.' for 'Not Used':

       N :  nearby sources affecting SASS flux determination
       P :  possible problem with position determination
       E :  source extended beyond SASS extraction radius
       D :  complex diffuse emission pattern
       M :  source missed by SASS
  

New_Data_Flag
Some additional flags, in the order RIV and a fourth flag that is currently not determined and unused, according to the following scheme, where the possible values are 'T' for True, 'F' or '_' for False, and '.' for 'Not Used':

       R :  source counts and extraction radius was recalculated
       I :  broad band image is available on MPE Website
       V :  variability flag (not yet filled by MPE)
  

Count_Rate
The vignetting-corrected source count rate in the broad energy band (pulse height amplitude (PHA) channels 11 - 235), in counts per second. A value of 0 means that this information is not available. The following conversion factors are suggested by MPE, assuming a photon spectrum which can be modeled by a power law with an index N and no absorption:

               1 count/sec  = 10.4E-12 erg/cm^2/s   for   N = -1
               1 count/sec  =  5.6E-12 erg/cm^2/s   for   N = -2
               1 count/sec  =  3.8E-12 erg/cm^2/s   for   N = -3
  

Count_Rate_Error
The error in the vignetting-corrected source count rate, in counts per second. A value of 0 for this parameter means that the error has not been determined.

Background_Count_Rate
The background vignetting-corrected count rate in counts per second per square arcminute. A value of 0 means that this information is not available.

Exposure
The exposure time in seconds. A value of 0 means that this information is not available.

Hardness_Ratio_1
The usual ROSAT PSPC HR1 hardness ratio defined as HR1 = ( B - A ) / ( B + A ) , where A = count rate in pulse height amplitude (PHA) range 11 - 41, and B = count rate in PHA range 52 - 201. The values for the hardness ratios HR1 and HR2, and their associated errors are not available, if all the values are 0.

Hardness_Ratio_1_Error
The error in the hardness ratio HR1. If the actual value of the error in HR1 exceeds 9.99, it is set to 9.99 in this catalog. Also note that the true error of HR1 is probably larger than this formal value. The values for the hardness ratios HR1 and HR2, and their associated errors are not available, if all the values are 0.

Hardness_Ratio_2
The usual ROSAT PSPC HR2 hardness ratio defined as HR2 = ( D - C ) / ( D + C ) , where C = count rate in PHA range 52 - 90, and D = count rate in PHA range 91 - 201. The values for the hardness ratios HR1 and HR2, and their associated errors are not available, if all the values are 0.

Hardness_Ratio_2_Error
The error in the hardness ratio HR2. If the actual value of the error in HR2 exceeds 9.99, it is set to 9.99 in this catalog. Also note that the true error of HR2 is probably larger than this formal value. The values for the hardness ratios HR1 and HR2, and their associated errors are not available, if all the values are 0.

Source_Extent
The source extent, in arcseconds. This is the amount by which the source image exceeds the point spread function.

Extent_Likelihood
The likelihood of source extent; if this exceeds 9999, it is set in this catalog to 9999. A value of 0 means that this information is not available.

Detect_Likelihood
The likelihood L-src of source detection, defined as L-src = -ln(Q), where Q is the probability that the observed distribution of photons originates from a spurious background fluctuation; in other words, L-src = -ln(1-P), where P is the probability of the source existence. If this exceeds 9999, it is set in this catalog to 9999. A value of 0 means that this information is not available.

Extraction_Radius
The extraction radius, in arcseconds. If this exceeds 9999 (e.g., as for the Vela SNR), it is set in this catalog to 9999. A value of 0 means that this information is not available.

Priority_Flags
A set of priority flags describing the sliding window detection history using either the background map (M) or the local background (L), where 0 = no detection, 1 = detection. The order of the flags is: M-broad, L-broad, M-hard, L-hard, M-soft, and L-soft. A value of 0 means that this information is not available.

High_Detect_Range
The PHA range with the highest detection likelihood: A: channels 11-41, B: 52-201, C: 52-90, D: 91-201, while empty or b means over the broad range of channels 11-235.

Vignetting_Factor
The Vignetting factor. A value of 0 means that this information is not available.

Date_Included
The date when the source was included: blank means that the source has been removed.

Date_Modified
The date when the source properties were changed: blank means that the source has not been changed.

Number_Ids
The number of identification candidates in the correlation catalog.

SASS_Field_ID
The identification number of the SASS field. An overview of the field structure is available at the URL: http://www.xray.mpe.mpg.de/rosat/survey/rass-bsc/sup/psplit.ps.gz

SASS_Source_Number
The SASS source number (MASOL number) in the SASS field specified in the parameter sass_field_id.

Proximity_Flag
The number of nearby RASS detections in three ranges of distances from the source: 0 - 5 arcmin (first digit), 5 - 10 arcmin (second digit), and 10 - 15 arcmin (third digit). A value of 9 for any of these digits indicates that there were 9 or more RASS detections.

Time
The start time of the observation.

End_Time
The end time of the observation.

Detect_Reliability
The reliability of the source detection, where this is in the range from 0 to 99, where 99 means the highest reliability.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 25-Jun-2008