Message-ID: <33099.192.33.116.167.1134502439.squirrel@webmail.gb.nrao.edu>
Date: Tue, 13 Dec 2005 14:33:59 -0500 (EST)
Subject: VLBI run BB184 in Green Bank
From: "Toney Minter" <tminter@nrao.edu>
To: gbtlocal@nrao.edu, gbtops@nrao.edu, analysts@aoc.nrao.edu,
        vlbaops@aoc.nrao.edu
Cc: jbraatz@nrao.edu
Reply-To: tminter@nrao.edu
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We were late getting the GBT observing going due to several
reasons.  We had to do emergency changes to a receiver's
cyrogenics which took a little longer than planned.  We also
had to do some follow-up checks of the GBT pointing to make
sure that we could participate in the observations due to
snow and ice on the dish surface and on the sub-reflector.
We started observing at about 12:16 UT.

During the whole observing run it was snowing in Green Bank.
There was significant snow and ice build-up on the surface
of the dish (5-6 inches [13-15 cm] is reported in some places
on the surface during maintenance the day after the observations).
The Tsys values were typically between 50 and 60 K during
the run.  The apperature efficiency was down from the
expected 70%  to values in the 50-55% range - via back of the
envelope calculations and assuming that the pointing source
flux was correct.

The data from the GBT should be treated with some caution
due to the observing conditions.
Toney Minter