[vsnet-chat 3600] Re: re NSV 12041 [UCAC1 data]

[aah@nofs.navy.mil]

Oops.
  I forgot that USNO-A1.0 and USNO-A2.0 had different
crossover points between northern and southern surveys.
The -21 degree zone in USNO-A2.0 is from the southern
Schmidts, and those plates are what John Graves mentioned:
1976 and 1987, non-contemporaneous.  The USNO-A1.0 catalog
used Palomar POSS-I plates for this zone, and these were
contemporaneous.  Yet another difference to keep in mind.
Sorry!  This Northern observer keeps neglecting his
southern sky studies!
Arne

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