Mark Pitts and Eugene Magnier have generated a synthetic grizy DVO database using the 2MASS PSC JHK photometry, the Tycho photometry, and (to a limited extent) the USNO-B photometry. The IPP is using this database as the main initial astrometric and photometric reference for the PS1 GPC1 observations. The photometry is synthetic in the sense that the grizy magnitudes are generated by fitting an extinction and main sequence spectral class to the JHK (and other) photometry, then determining the grizy photometry for such an object.

The complete catalog is rather larger (~100GB); please contact us for assistance in downloading it if you need it. We also have a bright-end catalog available which is limited to 15th magnitude -- if any of the five filters is brighter than 15th mag, then the object is accepted. This catalog is available as a 3GB tarball, and is only 15GB when uncompressed.

catdir.synth.bright.tgz

In addition, we are making available a subset of the IPP code needed to read and visualize the data from that catalog:

Ohana.20081024.tgz

To build this suite, unpack the tarball and run configure. It will warn you of any missing libraries. It does not need anything exotic: libreadline, libjpeg, libpng, libz, libX11, libpthread, and libm. Most Linux boxes will have these already, but some may have only the runtime, not the developer versions (eg, Ubuntu or RedHat? basic installations). If you have trouble getting your libraries, please look at the installation instructions for the full IPP.

See the DVO pages for examples of using DVO to interact with this database. For a simple extraction of a region on the sky, you can use the command getstar as follow:

getstar -D CATDIR (path to catdir.synth.bright) -format PS1_DEV_1 -photcode g -o test.fits -region 0 0 1 1

to extract the 'g' measurements from the region RA,DEC = 0,0 to 1,1 (in decimal degrees). Or:

getstar -D CATDIR (path to catdir.synth.bright) -format PS1_DEV_1 -photcode g -o test.fits -radius 0 0 1.5

for the measurements from the 1.5 degree region around the coordinate 0,0.