******************************************************************* README file for the GALEX/COSMOS EM-photometry catalog, version 3 ******************************************************************* Note: version 3 is the first released version This catalog was created using u*-band priors and the EM-algorithm. Appropriate references for a description of the method are: Guillaume, M., Llebaria A., Aymeric, D., Arnouts, S., & Milliard, B. 2006, Proceedings of the SPIE, Volume 6064, pp. 332-341 This is the current reference, and contains all the basics of the method and algorithm. A more specific reference for this catalog will be available soon. Zamojski, Arnouts, Vibert, Schiminovich & Milliard (2008, in preparation) The algorithm was run on the four NUV and the four FUV GALEX images covering the COSMOS field. It was run on the "-int" images (intensity maps) obtained as a product of the GALEX pipeline processing, version 1.61. The u*-band mosaic image and SExtractor catalog used as priors in this run were generously provided by Henry McCracken (IAP) and are based on CFHT-u* observations of the COSMOS field. These are NOT included with the release. People interested in the priors should contact both Henry and myself for more information. ***************************** Description of the columns ***************************** Column 1 - Number: This is the ID of the object in the u*-band prior catalog. This is NOT the same as the ID in the general COSMOS photometry catalog. Column 2,3 - Ra & Dec (in degrees) Column 4,5 - Image from which the photometry was measured. (GALEX covers the COSMOS field in 4 pointings) Column 6,7,8 & 9 - Position of the object in the NUV and FUV images. (in pixels; 1 pix ~ 1.5") Column 10,11 - Measured background around the object (in counts/s). Column 12,13 - Measured flux of the object (in counts/s). Column 14,15 - Error in the flux measurement (counts/s). Column 16,17 - AB-magnitude corresponding to the measured flux. Column 18,19 - Magnitude error. Column 20 - u*-band magnitude used as the prior magnitude to start the iterative algorithm. This is a MAG_AUTO with additional deblending, and can differ from the u*-band aperture magnitude in the general COSMOS photometry catalog. Column 21, 22 - NUV and FUV mask flags. 0 means ok. 1 means that the photometry of the object could be problematic due to either a nearby bright object, or image defects. Column 23 - The SExtractor CLASS_STAR from the u*-band prior catalog. Objects with a CLASS_STAR > 0.8 were modeled with a simple PSF whereas the ones with a CLASS_STAR < 0.8 were modeled with a profile based on their u*-band image convolved with the GALEX PSF. **************************************************************************** Written by Michel Zamojski, June 5th, 2008 (SSC)