[daip] explain shift

[Lorant Sjouwerman]

it says
--
of a sin-projection image.  Use IMXY to give you RA and Dec and then
compute the shifts as:
         SHIFT(1) = cos (Dec_0) * (RA - RA_0)
         SHIFT(2) = Dec - Dec_0
in arc seconds.  The _0 refers to the reference coordinate.
--
which is correct if one doesn't forget to multiply shift(1) or RA and
RA_0 by 15 ["/s], though I think most people will forget; maybe it
should be added as a reminder.. Anyway


Regards,

Loránt Sjouwerman - Scientific Services - lsjouwerman at nrao.edu
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