Appendix 3. Long Exposure (6x) Scan Databases, Catalogs and Images
6. 6x Catalog Generation
a. Overview
Figure 1 - Illustration of 6x Catalog Generation Results
A 3-color (J/H/Ks) composite 6x Atlas Image, centered at approximately ra,dec=93.07°,+48.56°, showing a section of one 6x scan of the Abell 553 field. This scan is one of 11 contiguous 1° 6x scans of the field acquired on the night of 2000 November 17 UT from Mt. Hopkins.
Rolling the cursor over the image switches between overlays showing the location of 6x point and extended source WDB extractions and sources selected for the 6x-PSC and 6x-XSC. 6x-PSWDB and 6x-XSWDB extractions are denoted by the red squares and cyan circles in the first view, respectively. In the second view, sources selected for the 6x-PSC and 6x-XSC are denoted with green or white boxes and yellow or white circles, respectively.
The source selection phase of catalog generation filters out low SNR extractions, most of which are unreliable noise detections, extractions that are identified with image artifacts produced by bright stars, and extended source candidates that have a low confidence extended classification.
Objects that fall in overlap region between adjacent scan may have more than one, independent detections in the 6x-WDBs. The multiple source resolution process selects one unique detection of multiply-detected sources for the Catalogs using a simple geometric decision algorithm. 6x-PSC and 6x-XSC sources shown in white along the east and west edges of the image are the source detected in and selected from the two adjacent scans.
| Figure 1 - 3-color composite 6x Atlas Image showing a section of one scan of the Abell 553 field. Red and cyan overlays show 6x-PSWDB and 6x-XSWDB entries in the first view. Greens and yellow overlays show sources selected for the 6x-PSC and 6x-XSC in the second view. White square and circles show 6x-PSC and 6x-XSC sources that are selected from adjacent scans. |
[Last Updated: 2007 January 8 by R. Cutri]