[daip] Coordinate system of antenna table in FITS file produced by FITTP

[Bojan Nikolic]

Hello,

I have recently been working with "AIPS AN" tables in FITS files,
produced both by AIPS and other systems. I would like to confirm the
coordinate system that AIPS writes this information in. 

As far as I understand the FITS-IDI document, the coordinate system
should be that such that the x-axis runs from centre-of-mass of the
Earth to the intersection of Equator and the Greenwich meridian. This
coordinate system should apply both to ARRAYX, ARRAYY, ARRAYZ keywords
and the STABXYZ column values.

Looking at output of AIPS, it seems to me that (ARRAYX, ARRAYY,
ARRAYZ) are indeed in this coordinate system, but that somehow for the
STABXYZ values the coordinate system x-axis is redefined to run from
centre of Earth to the intersection of *local* meridian and the
equator. 

It would be great if you could confirm what the coordinate system used
is.

Thanks in advance,
Bojan

PS. It would be very useful if there was a way to search the daip
archives! Perhaps just eliding the email addresses and letting them be
indexed by major the search engines?



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Bojan Nikolic               Tel:  +44 1223 339991
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