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COSMOS Sloan Digital Sky Survey (SDSS) Data                     Version 2.0
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The Cosmic Evolution Survey (COSMOS) is an HST Treasury Project to survey
a 2 square degree equatorial field, centered on RA=10:00:28.6 and
DEC=+02:12:21.0, using the ACS camera. The project also incorporates major
commitments from other observatories around the world, including the VLA
radio telescope, ESO's VLT in Chile, ESA's XMM X-ray satellite, and the
Japanese 8-meter Subaru telescope in Hawaii.

These data are imaging taken as part of the Sloan Digital Sky Survey (SDSS)
project.  The data were downloaded from the DR2 archive, and calibrated 
using the best photometry in the tsField files.  They were combined into a 
single image using the COSMOS astrometric frame generated from the VLA data 
and CFHT i* image.  These data are psf homogenized.  The filter transmission
profiles for each filter are included in the files SDSS_filter_N.txt, where 
"N" is the filter name.

The u' filter has a known red leak, however it is not given in the filter
profile provided by SDSS.

The PSF homogenization of these SDSS data are not perfect.  For a 3"
aperture, variations of approximately +/-0.05 mag are observed in the aperture
correction as a function of position .  The effect is smaller for colors
measured between two SDSS bands because the offsets are similar in all bands.

The key characteristics of these data are:

Telescope:		SDSS 2.5m Telescope
Instrument:		SDSS Camera
Data Release:		DR2
Integration time:	53.9s
Effective Wavelength:	472.3nm (g)
                        752.3nm (i)
                        621.3nm (r)
                        359.1nm (u)
                        885.5nm (z)
Filter Width:		130.0nm (g)
                        130.0nm (i)
                        120.0nm (r)
                         55.0nm (u)
                        100.0nm (z)
Flux unit:		nJy
Zero Point		31.4
Area:			4 sq degrees
Resolution:		0.15"/pix
Seeing:			1.97" (g, i, u, z)
                        1.0-1.7" (r)

PSF Homogenized:	YES

The data products available here include the following at each of
144 tiled positions:

    1) an image in units of nJy
    2) a map of the image RMS in units of nJy

A tile diagram is included with the data.

Reduced data were provided by the Sloan Digital Sky Survey Second Data
Release (SDSS DR2) http://www.sdss.org/. Images were combined by
Peter Capak (capak@astro.caltech.edu) using the IMCAT software package.
More information on IMCAT can be found at:

    http://www.ifa.hawaii.edu/~kaiser/imcat/

This data was prepared for release by:

Peter Capak (capak@astro.caltech.edu)
Patrick Shopbell (pls@astro.caltech.edu)

Further information may be obtained from the COSMOS web page:

    http://cosmos.astro.caltech.edu/

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