HRICFA - Einstein Catalog HRI CFA Sources
This database table consists of a preliminary source list for the Einstein
Observatory's High Resolution Imager (HRI). The source list, obtained from
EINLINE, the Einstein On-line Service at the Smithsonian Astrophysical
Observatory (SAO), contains basic information about the sources detected
with the HRI.
The HRI was one of the four focal-plane instruments in the Einstein
Observatory. The HRI, supplied by SAO, had the highest spatial resolution on
Einstein but had relatively low quantum efficiency.
The HRI source list contained in the Einline database is version #1, released
on 17 November 1989. Results taken from this list should be used with caution,
as the list is in a more primitive state than the IPC source list (contained in
the IPC database). The data were taken essentially unchanged from the results
of the HRI Rev 1 processing at SAO. The HRI source list has been screened
manually for obvious errors, but not as thoroughly as the IPC list. In
particular, a number of extended sources were not picked out by the standard
source detection algorithm and so are not included in the HRI list. As of
spring 1991 (when this database was created), the final version of the HRI
Source Catalog, the analog of the IPC Source Catalog, had yet to be released.
The galactic latitude of the source, calculated from the given RA
Each source has been assigned a `catalog designation`. The catalog designations
have the format `HRIhhmmss+ddmm`, with `hhmmss` representing hours, minutes and
seconds of RA and `+ddmm` representing degrees and minutes of declination.
The corrected count rate. For the HRI source list, the count rate is obtained
by summing all counts within a circle of radius 18 arc seconds centered on the
source position, and then applying the HRI correction factors for exposure
time, vignetting, deadtime, mirror scattering, and quantum efficiency.
The count rate error is estimated with this equation:
Error = ((BCTS^1/2)/BCTS) * Count Rate
where `BCTS` is the sum of all counts inside the detection box of side = 12 arc
The declination of the source.
Field number for the source.
The galactic longitude of the source, calculated from the given RA
The common name of the source, assigned by cross-correlating the HRICFA database
with other online catalogs.
90-percent uncertainty in the coordinates in arc seconds. It includes a
statistical contribution added in quadrature to a systematic term.
The right ascension of the source.
HRI source flag.
The source flag codes are as follows:
* X = This source shows obvious extent.
* U = The count rate for this source has been underestimated, because it is
either extended, confused, or at the edge of the field of view.
* C = The source lies in a confused region; its position and count rate may be
seriously in error.
This is a sequence number for the observation associated with each source. The
sequence number is a unique numeric identifier for an observation, allocated
sequentially at time of proposal submission.
The signal-to-noise ratio of the detection.
For the HRI source list, this is a conservative estimate, since for small
numbers of counts the Poisson errors are significantly asymmetric.
Questions regarding the HRICFA database table can be addressed to the
HEASARC User Hotline.
If you have any problems, please consult the help
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