AAVSO Photometric All-Sky Survey (APASS), underway since 2010,
covers the entire sky from 7.5 < V < 16.5 magnitude, and in the BVugrizY
bandpasses. A northern and a southern site are used, each with twin ASA
20cm astrographs and Apogee Aspen CG16m cameras, covering 2.9x2.9 square
degrees with 2.6arcsec pixels. Landolt and SDSS standards are used for
all-sky solutions, with typical 0.02mag calibration errors on the bright
end.
Data Release 10 is a complete reprocessing of all 500K images taken with
the system, including hundreds of nights not part of DR9. Sextractor is
used for star finding and centroiding; DAOPHOT is used for aperture
photometry; the astrometry.net plate-solving library is used for basic
astrometry, supplanted with more precise WCS that utilizes knowledge of the
optical train distortions. With these changes, DR10 includes many more
stars than prior releases.
More information is available at http://www.aavso.org/apass.
