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## RASSFSC - ROSAT All-Sky Survey: Faint Sources |
HEASARC Archive |

**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.