2 2MASS CCFST ivo://irsa.ipac/2MASS/Catalog/CombCalFieldSource NASA/IPAC Infrared Science Archive 2MASS team 2003-03-26 IRSA Support Team

irsasupport@ipac.caltech.edu all sky survey Photometric calibration for 2MASS was performed using observations of calibration fields made at regular intervals during each night of survey operations. Measurements of standard stars in the fields were used to derive the photometric zero point offsets as a function of time during each night. Atmospheric extinction coefficients were derived from 2MASS observations made over long periods. 2MASS calibration fields, or tiles, are 1° long in declination and approximately 8.5' wide in right ascension. There are 35 regular survey calibration fields distributed at approximately two hour intervals in right ascension near declinations of approximately -30°, 0° and +30°. An additional five calibration fields were defined in and around the Large and Small Magellanic Clouds to support the deep observation (6x) campaign towards the end of survey operations. Over the course of the survey, the regular calibration fields were scanned between 562 and 3692 times in nominally photometric conditions. Equatorial fields were observed from both observatories, so were observed more frequently than those near ±30° which were observed with only one telescope. The special Magellanic Cloud calibration fields were observed 108 to 468 times between November 2000 and February 2001. The Combined Calibration Field Source Table contains the positions, aperture photometry, uncertainties, quality flags and cross-references to entries in the All-Sky Point and Extended Source Catalogs. A source was required to be detected on both the combined north-going and south-going images to be included in the extracted source database for a field. The positions and photometry provided are the average values measured on the north- and south-going combined images. https://irsa.ipac.caltech.edu/data/2MASS/docs/releases/allsky/doc/seca4_1.html Catalog Research served-by IRSA TAP service 2 https://irsa.ipac.caltech.edu/SCS?table=deepcal_src& 180 2147483647 false 28.630407 0.219977 0.0028 2 To access this resource via TAP, issue ADQL queries on the table named deepcal_src. https://irsa.ipac.caltech.edu/TAP 2 https://irsa.ipac.caltech.edu/cgi-bin/Gator/nph-dd?catalog=deepcal_src Infrared twomass 2MASS Calibration Scan Working Databases and Metadata deepcal_src2MASS Combined Calibration Field Source Table