The 2MASS 6x Working Databases/Catalogs in GATOR

A special set of observations that utilized exposure times six times longer than the main 2MASS survey measurements were conducted in the final year of 2MASS observatory operations. The 2MASS "6x" observations achieved sensitivities ~1 mag deeper than the main 2MASS survey, and covered approximately 590 deg² of sky in 30 discrete regions.

The 2MASS 6x Point and Extended Source Working Databases (6x-PSWDB and 6x-XSWDB) contain all detections extracted from the raw 6x imaging data during pipeline data reduction. The 6x WDB entries include reliable detections of astrophysical sources, as well as spurious detections of noise excursions, image artifacts and transient events such as meteor trails, cosmic rays and hot pixels. In addition, the WDBs may contain multiple, independent detections of objects scanned more than once during the 6x observations.

The 2MASS 6x Point and Extended Source Catalogs (6x-PSC and 6x-XSC) are a subset of extractions in the 6x-PSWDB and 6x-XSWDB that have been identified to be high reliability source detections, with only one measurement of sources detected multiple times for uniformity. In the case of the 6x-XSC, the catalog entries are selected to be objects that are truly extended with respect to the 2MASS point spread function.

i. How to Access the 6x Catalogs using GATOR

Unlike the 2MASS All-Sky Release Point and Extended Source Catalogs, the 6x-PSC and 6x-XSC are not released as separate tables, but are integrated into the respective 6x Point and Extended Source WDBs. Entries comprising the Catalogs are denoted in the WDBs with the cat flag, and have a value of cat="1".

Queries on the 2MASS 6x source tables with GATOR default to searches of the full 2MASS 6x-PSWDB or 6x-XSWDB, with the additional constraint of selecting only database entries with the highest probability of reliability (rel="A"). To search the subset of rows that constitute the 6x-PSC or 6x-XSC:

1. Enter cat=1 in the "Additional Constraints (SQL)" dialog box at the bottom of the GATOR query page, and


2. Change the "Reliability Limit" to "A-F(all)" by clicking that radio button in the "Reliability Limit" dialog box in the center of the query page.

The second step is necessary because the catalog selection rules for the 6x catalogs are different than the reliability scoring rules, and result in the inclusion of a small fraction of sources in the catalogs that have reliability scoring lower than "A".

For more information about the 2MASS 6x observations and data products, please see Appendix 3 of the Explanatory Supplement to the 2MASS All-Sky Data Release and Extended Mission Products