Corrections to USNO-B plates from PPMX
This table contains, for each field that went into USNO-B1, a
correction derived from matching the USNO-B1 positions for that plate
with the PPMX ones (used as a representation of ICRS) and deriving a
mean offset of the objects from that particular plate for them. We did
not attempt to derive magnitude-dependent corrections (although it is
known that the true residuals depend on both magnitude and color).
This service uses code provided by Astrometry.net. For more details
visit http://astrometry.net. The field metadata were, in part, taken
from CDS' Vizier service.