Astrometry forums full#
Astrometry forums registration#

The quality of data and sky coverage south of -30 deg are very uneven. DR1 did include some objects south of the nominal survey limit. Note that the DR2 version of the catalog also has a sharp cut (almost everywhere) at a declination limit of -30 degrees. The approximate boundaries of the missing data are given in the table below.

The most noticeable missing areas are long narrow strips in declination. The other two plots show closeups with more detail. The first figure shows a schematic plot with the locations of missing data. The figures below show where data are missing. Note that an earlier issue where the MeanObject objects were missing (over a much larger area) has been fixed. The missing regions lie in areas where no sources were ingested into the ObjectThin table (only ~1.5 sq deg). The current version of the database is missing data over about 0.016% of the survey (4.9 square degrees). The headers also lack the TIMESYS = 'TAI' keyword, which is important if you care about the image observation dates at an accuracy of 30 seconds. The fix is to insert the keyword RADESYS = 'FK5' in the header.

Astrometry forums full#

The full skycell FITS images do not have a RADESYS keyword, which leads some software (including DS9 v8) to incorrectly interpret the coordinates as being equinox 1950 rather than equinox 2000. The files also use the tile-compressed image format. The fluxes have been non-linearly scaled using an asinh transformation.

FITS image headers use the obsolete PC001001, PC001002, etc., keywords for the WCS.

There will also be errors in the stack positions (but not mean epoch positions) in the catalogues. As a result, both warp and stack images may have incorrect WCS, and in extreme cases double objects may be visible in the stacks.

There are some astrometry issues at the ~0.5' level near the pole (mostly above 85 deg declination) which have caused problems with the stacking.

Astrometry forums registration#

Some images near the celestial pole have registration issues that lead to poor photometry and astrometry.The catalog quantities are more accurate due to post-image-processing improvements. The astrometric and photometric keywords in the image headers are slightly inconsistent with the astrometry and photometry for catalog objects.The stack positions (raStack, decStack) have considerably larger systematic astrometric errors than the mean epoch positions (raMean, decMean).These are expected to be filled in during the coming months. Approximately 4.9 square degrees (0.016% of the survey area) has sources that are missing due to various issues in the database population procedures.Users of the current PS1 DR2 data should be aware of a few issues and inconsistencies in the data.