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XCOLL: Help

XCOLL - Master X-Ray Collimators Catalog Database

Overview

The XCOLL database is a master catalog which contains selected parameters from HEASARC X-ray catalogs containing the results of surveys made with collimated detectors. In general these sources have error boxes that are relatively large and irregularly shaped. XCOLL was created by copying all of the entries and common parameters from the following catalogs:
---
 * A1 - HEAO 1 A-1 X-Ray Source Catalog   

 * A2LED - HEAO 1 A-2 LED Catalog 

 * 3ARIEL - 3A (Ariel V) Catalog 

 * 4UHURU - 4th UHURU X-ray Catalog (Forman et al. 1978) 
---
The XCOLL database has many entries but relatively few parameters; it provides users with a general overview of X-ray sources detected with collimated detectors. Each entry in XCOLL has a parameter called `database` which indicates from which original catalog database the entry was copied; users can "browse" that original catalog should they wish to examine ALL of the parameter fields for a particular entry.

Also, to obtain more detailed information about original catalog, or about the instrument used in the experiment, users should access the online help for that catalog. For example, to access the help for the A1 catalog while XCOLL is loaded as the current database, type "dbhelp/dbname=A1".

For some entries in XCOLL, certain of the parameter fields are blank (or have zero values); this indicates that the original database did not contain that particular parameter. (For example, the `flux (mCrab)` parameter is often blank for this reason.)


Parameters

Name
The commonly-used name of the sources.
Catalog_Designation
The catalog designation is the name of the source as assigned in the particular
catalog from which it comes.  
Serial_Number
This is a running serial number used within some of the catalogs to indicate
source order.
Database
The name of the HEASARC database from which this entry was taken.
(For more information on the contents of any of the HEASARC databases, type
`dbhelp/dbname=xxxxx` where `xxxxx` is the database name.)
RA
The Right Ascension of the X-ray source, in degrees.
Dec
The Declination of the X-ray source, in degrees.
LII
The galactic longitude of the X-ray source.
BII
The galactic latitude of the X-ray source.
RA1
Right Ascension of the first corner of the error box surrounding the source.
RA2
Right Ascension of the second corner of the error box surrounding the source.
RA3
Right Ascension of the third corner of the error box surrounding the source.
RA4
Right Ascension of the fourth corner of the error box surrounding the source.
Dec1
Declination of the first corner of the error box surrounding the source.
Dec2
Declination of the second corner of the error box surrounding the source.
Dec3
Declination of the third corner of the error box surrounding the source.
Dec4
Declination of the fourth corner of the error box surrounding the source.
Count_Rate
The count rate associated with the source (counts per second).  The associated 
error parameter is `count rate error`. 
Flux_mCrab
The flux in milliCrab.
Flux_mCrab_Error
`Flux mCrab error` parameter contains the error associated with `flux mCrab`,
also in milliCrab.
Flux
The flux in erg s**-1 cm**-2, usually obtained by multiplying the given count
rate by a conversion factor.  The `flux error` parameter contains the
associated error, in the same units.
Filter
The name of the filter used for the observation, if any.
Exposure_Time
The exposure time for the observation, in seconds.
Sequence_Number
The observation sequence number for the source, if present.
Detection_Significance
The probability that this source is a result of background fluctuation.  
Source_Size
The size of the source if it is extended, in arc seconds.
Class
The BROWSE object classification flag. 

Contact Person

Questions regarding the XCOLL 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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