Appendix 1. Introduction to the 2MASS Extended Mission and Ancillary Data Products


4. Cautionary Notes

All 2MASS survey, 6x and calibration observations were made with the same facilities using essentially the same observing mode, and the raw imaging data acquired from these observations were all processed with variants of the same software pipeline. As a result, the reduced image and extracted source data from all 2MASS observations share similar characteristics and limitations. However, the 2MASS Extended Mission Ancillary Products are fundamentally different by design than the highly reliable and uniform All-Sky Release Catalogs and Image Atlas. Because of these differences, the Extended Mission products should not be used the same way as the All-Sky Release PSC and XSC. Instead, the Ancillary Products should be used as a resource to learn more about individual objects where detailed follow-up is possible, or to conduct studies over small regions of the sky that do not require the high degrees of uniformity and reliability that characterize the All-Sky Catalogs.

Some of the key differences between the Extended Mission and All-Sky Release products about which you should be aware are:

Because of the common heritage of the 2MASS Extended Mission and All-Sky Release data products, users are strongly encouraged to first review Section I.6 of the Explanatory Supplement that contains detailed Cautionary Notes pertaining to the 2MASS All-Sky Release products. Sections A1.4a-d that follow below contain high-level summaries of key limitations and features of the Survey Reject Tables and Full Image Atlas, the 6x Working Databases, Catalogs and Image Atlas, and the Calibration Working Databases and Image Atlas. However, these are not complete descriptions of all limitations and features for each product, and they do not include summaries for the Merged Source Information Tables or the Combined Calibration Scan Images and Source Lists. Please see the Appendices that describe each of the Extended Mission data products for comprehensive listings of the Cautionary Notes:



A1.4.a. General Cautionary Notes for the Extended Mission Ancillary Data Products

A1.4.b. Cautionary Notes for the Extended Mission Point Source Reject Tables, Working Databases and 6x Catalog

A1.4.c. Cautionary Notes for the Extended Mission Extended Source Reject Tables, Working Databases and 6x Catalog

A1.4.d. Cautionary Notes for the Extended Mission Atlas Images

[Last Updated: 2006 December 20; by R. Cutri]


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