Appendix 6. Merged Working Database Source Information
3. Merged Database Table Formats
c. Merged Source Cross-Reference (Link) Tables
The following table contains brief descriptions of the entries in the Survey, 6x and Calibration Merged Source Cross-Reference Tables. The Cross-Reference Tables for the Merged Point and Extended Sources have the same format.
The Cross-Reference tables contain information linking each merged group with its individual extractions in the respective WDB. The tables contain one row for each WDB extraction that has been associated with a merged source group. Each row in the tables contains the unique merged group identifier (gcntr), the unique WDB identifier (cntr/pts_key for Point Source WDBs and cntr/ext_key for Extended Source WDBs) and the number of groups with which that WDB extraction has been associated (ngrp). A WDB extraction may be associated with more than one merged group in confused situations. The cntr/pts_key/ext_key values for such WDB extractions will appear more than once in the Cross-Reference Tables, accompanied by the gcntr of each of the groups to which it has been associated.
Searching this table for all entries with a particular value of gcntr returns the identifiers of all WDB entries in a particular merged group. Alternately, searching this table for a particular value of cntr/pts_key/ext_key returns a list of all groups to which a particular WDB extraction belongs.
The order of the entries in this table is the same as that presented in the IRSA/GATOR query page for these tables.
The columns in the following table are:
- Column Name: The parameter name in the Merged Source Information Cross-Reference table. Click on this to go to the section of the Explanatory Supplement where the derivation and/or usage of that parameter is described in more detail.
- Format: The ascii-equivalent format of the field in the PSWDB, expressed in "C" readable notation. This is useful when parsing the aligned tabular output from IRSA/GATOR. Although the data values will conform to these formats, the actual width of the field in the GATOR output may be padded with extra blank spaces to accommodate column headers. Note that some fields contain null values that will require special handling when parsing tables drawn from IRSA/GATOR output.
- Units: The units of the parameter. A value of "---" in this column means that the parameter is dimensionless.
- nulls: A "yes" in this column means that this parameter can be null in the Merged Source table. A "no" means that there will always be a value in this column in the table. Note that null values are represented differently in the IRSA/GATOR output and the ascii DVD-ROM or ftp versions of the Merge Source tables.
- Description: A brief description of the parameter and its values.
| Column Name | Format | Units | nulls | Description |
|---|---|---|---|---|
| gcntr | %10d | --- | no | Unique identifier of the merged group within
a given database. This value is set to be the
cntr/pts_key value of the "seed" extraction for the group (see
A6.2).
Gcntr is not unique within a Cross-Reference Table. There are as many entries with the same value of gcntr as there are extractions in the group (napp). The gcntr identifier is cross-referenced in the individual WDBs and the Merged Source Information Tables (VI.4.a and VI.4.b). Note: Gcntr is unique only within a given database. Sources in the Merged Survey, 6x and Calibration Tables with the same gcntr identifiers are not the same object on the sky. |
| cntr/pts_key or cntr/ext_key | %10d | --- | no | Unique identifier of the extraction in the respective Point or Extended Source WDB that is associated with the group identified by gcntr. Cntr is not necessarily unique within the Cross-Reference table because an extraction may be associated with more than one merged group in confused situations. |
| ngrp | %3d | --- | no | Number of merged groups in which this
extraction is found. ngrp > 1 indicates confusion. |
[Last Updated: 2006 September 28; by S. Wheelock & R. Cutri]
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