• 2011-06-08 (MD): Silent update: 6169 objects copied from PPMX were affected by a PPMX bug that computed Ru magnitudes although at least one 2MASS magnitude was NULL. This resulted in large negative r1mags for these objects in PPMXL. The erroneous magnitudes have been set to NULL.
• 2016-04-20 (MD): Added vickers_pmra and vickers_pmde columns based on a global correction model for PPMXL proper motions as discussed in 2016AJ....151...99V.
• 2017-12-15 (MD): The corrections to USNO-B1 published in the the ppxml.usnocorr table had originally been computed against the original USNO-B rather than the version cleaned with Barron's list of spurious detections as advertised. This is now corrected. Individual corrections changed by up to 10%. If you used the table or the service ivo://org.gavo.dc/ppmxl/q/corr to correct positions obtained against USNO-B1, we advise to repeat the procedure with the corrected values.

Differences between USNO-B and PPMXL in positions and proper motions, on an all-sky one-degree grid. At each gridpoint we give the differences X(PPMXL)- X(USNO-B1.0) averaged over all stars in a sqrt(2)/2-degrees environment around the gridpoint given. The corrections given here should bring USNO-B based astrometry to the ICRS.

• stars
• Surveys
• Astrometry
• Proper motions

• PPMXL
• USNO-B

• Röser, S.
• Demleitner, M.
• Schilbach, E.
• Vickers, J. J.

• To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to PPMXL. For details, see the Creative Commons CC0 1.0 Public Domain dedication. Of course, you should still give proper credit when using this data as required by good scientific practice.

  
• https://spdx.org/licenses/CC0-1.0.html