Notes from the GBT Commissioning Coordination Meeting
15 November 2002

1.  GBT Review Meeting Summary

Phil discussed the GBT Review and some changes in priorities arising from
it.  The review meeting appeared to be very successful in informing staff
from around the Observatory of the status of the GBT.  There also appears
to be an opportunity for increased participation by scientists from other
sites.  The largest immediate benefit to the commissioning and development
program is that we received some very useful input on priorities.  We
intend to act on this input, and will make the following changes:

We will have only one top priority at a time in each major activity
area.  The top priority in an area means that project gets first call on
the resources necessary to accomplish its tasks, including people and
telescope time.  Top priorities in three major areas are

Commissioning -> Spectral Baseline Improvements
Development Projects -> PTCS
Antenna work -> Azimuth Track Work

There are several implications of these priorities, the most important of
which are the things that are in second priority, and those things we will
not do at all.  K-band commissioning is second priority and remains very
important.  We will carefully review the K-band plan and do the things
that enable the most observing programs first.  We will worry less about
completeness in the near term.  Work on the Spectrometer also remains very
important (and is essential for the baseline investigations, as well as
general observing needs).  To allow adequate resources for the baseline
investigations, work on the 3 mm and 1 cm receivers will be temporarily
suspended.  The Beam Forming Array project will remain suspended until the
baseline work is completed.  An assessment of that project will be made in
March or April.

There may be occasional conflicts between priorities in the major areas
listed above, but for the most part, different people are involved.  Such
conflicts should not be major and will be resolved case by case.

We will also be making some changes in program and project management to
allow the projects above to proceed efficiently.  These changes are still
under discussion.

2.  Commissioning work

The week was largely taken up with the GBT Review meeting.  There have
been some realignments of the observing schedule in regard to the pulsar
spigot card work and baseline investigations.

Jim Braatz reported some of his experiences in recent observations with
the Spectrometer.  Mark Clark noted that he and others working on the
Spectrometer would like to be called whenever problems arise.  They are at
work to improve Spectrometer reliability, and need to see problems as they
happen, as they often cannot be reproduced later.

3.  Program activities

John reported on RFI work.  He noted that the RFI group has had one person
working full time on the new visitor center for the past month testing the
shielded rooms there and the various appliances that are being installed.
Two techs are at work on RFI work on the telescope.  Work on RFI
mitigation of the laser rangefinders is presently on hold.

4.  Baseline work

Roger described some work in which he used the DCR to examine the total
power stability of various components in the IF chain.  The new optical
modulator that may have reduced 2.4 MHz standing wave has been received,
but has not been installed.  Tests are also underway on the old modulators
that do not have the gain feedback loop.  The X-band receiver will be
pulled off the telescope early next week to begin work to install the new
generation, 3-13 GHz indium phosphide HFETs.  The CDL believes they can
have these amplifiers for us in a couple of weeks.  Gain instabilities in
the amplifiers are believed to be a major source of the baseline problems
in that band.  Rick noted that the IF noise source is being kept on all
the time now so that it is fully warmed up and stable when needed.  He
stated that progress is being made in narrowing down the list of
components that can contribute to gain instability.

5.  Spectrometer

Rich reported that Ray Escoffier had been out this week to work on the
pulsar spigot card.  The pulsar data is scrambled when it comes out of the
Spectrometer, but can probably be de-scrambled.  Rich also noted that they
have found that data can bleed across phase bins and that some additional
blanking techniques will be required.

Rich and John reported that the LO blanking problem has probably been
solved.  As John described in a later email, "the bug was that the machine
cycle count for bin 0 (switching signal phase == bin in this context) was
always being used to normalize the lag, instead of the proper count value
for each bin."  This was a significant find, and should fix one class of
spectral baseline problem that has been observed.


6.  Software status

Joe B. reported that he had provided a script to move the antenna to snow
dump position.  It was tested on Thursday and appeared to work.  Amy
reported that she was working on Spectrometer multi-bank capability and
had successfully run 450 scans.

7.  AIPS++

Joe M. and Steve Myers were in transit following their visit to Green Bank
this week.  Jim reported that there was no new Stable yet.  Work on Filler
profiling has been underway.  The students working on Ed Churchwell's
program had some difficulties in their data reduction and had sent a
report.  Joe has been in contact with them.  Joe and Nicole took advantage
of the Review Meeting visit to work on improving coordination of AIPS++
and M&C releases.

					PRJ  // 16 November 2002