The traditional pointing model corrects for repeatable pointing errors
that change on timescales of months but not days. These errors can
typically be associated with physical imperfections in the telescope
structure (e.g., tilt of the azimuth track). Nonrepeatable pointing
errors are more difficult to characterize and may vary on timescales
of tens of minutes and with telescope position. They are frequently
dominated by thermal effects. Offset pointing using nearby
calibrators can be used to correct for nonrepeatable errors.
J. J. Condon and Q. F. Yin have generated a list of 3399 calibrators
for large radio telescopes from the NRAO VLA Sky Survey (NVSS) which
uniformly covers the sky north of declination -40 deg (Condon & Yin,
2001, ASP 113, 362). The NVSS pointing catalog can be accessed using
the GBT observing interface. Below are links to the catalog.
NVSS Caltalog Information (ASCII)
NVSS Caltalog (ASCII)
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Last modified: Wed Oct 23 22:12:59 EDT 2002
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