Subject: Minutes of 3/13/00 3.5m User's Committee meeting
From: strauss@astro.Princeton.EDU
Submitted: Wed, 22 Mar 2000 08:45:07 -0500 (EST)
Message number: 423
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Apache Point Observatory 3.5m User's Committee Meeting
March 13, 2000
Attending: Jeff Brown, Lew Hobbs, Ed Turner, Michael Strauss, Bruce
Gillespie, Chris Stubbs, Alan Uomoto, Rene Walterbos
Agenda:
The situation with telescope image motion
A proposal to set aside time for SDSS follow-up
Cleaning up the APO User's list
A proposal to upgrade the DIS slit viewer
The vBNS situation
****************Telescope tracking and image motion********************
Stubbs: With new secondary, image quality is much better. However,
the image in the focal plane of all instruments has been bouncing
around. This is due to a variety of things, but the most important is
the fact that the telescope makes an adjustment to the secondary
position as a function of elevation (to keep things in focus). This
causes motion in the image plane, which may be due to problems with
the piezos that control the secondary. The correction to the
secondary position is also not being done consistently; the tilt is
not properly taken into account.
The immediate workaround, which seems to make things somewhat
better, is to invoke the secondary adjustment only during slews, and
not during guiding. This means that if you do a long exposure on an
object, you should ask the observing specialist to update the
secondary every, say, 1/2 hour.
To do this *right*, we need to do some further work on the topend,
so that these corrections are done correctly. There may need to be a
replacement of the piezos, there may be a broken flex pivot. We
definitely didn't have this with the old secondary, so there must be
something broken with the new secondary support.
Gillespie: The primary shows some astigmatism, due to stresses (of
unknown cause). We need to track this down. In April, we plan to
carry out an experiment of playing with some of the vent tubes to see
if they might be the cause of this.
There is a consensus that with the guider working, this is not a
showstopper for peoples' science, but there is a lot of momentum on
this problem, and we'd like to get it all cleaned up.
**************Set-aside time for SDSS follow-up work?*********
The SDSS is soon to start routine operations, with a corresponding
flood of interesting objects. Shall we take advantage of this by
setting aside a predefined block of time for follow-up of SDSS
targets? Alternatively, shall we ask SDSS institutions to set aside
their time explicitly for this? The consensus was that we already
have a mechanism in place, director's discretionary time, for fast
response to hot discoveries from the SDSS, and any time set aside
specifically for SDSS science would bypass the peer review of
proposals already happening at each institution. As a group, we were
not enthusiastic about this idea, although the concept is still alive
at the Director's level.
************Cleaning up the list of observers*********************
The observatory maintains a list of people:
http://www.apo.nmsu.edu/traininglist.html
of people certified to use the 3.5m telescope remotely. Many of those
people have not used the telescope in many years, and we would like to
trim it down to only those people who are relatively recently familiar
with the operation of the telescope.
We need to have a set of formal rules about how people might lose
their certification as an observer (e.g., not having been to the site
in X years, not having observed remotely in Y years....). In the
meantime, the User's Committee members from each institution are
requested to go through the list of certified people from their
institution, and indicate which are the active users.
There is a matter of observing efficiency here: people who haven't
observed for several months need some time to get back up to speed: spend an
afternoon before the night starts to get the rust off. The real issue
is that the proficiency of the median observer seems to be going
downhill recently. People are getting out of practice... The typical
time since the person was last at the site is getting longer and
longer.
**********Upgrading the DIS slit-viewing camera****************
Jom Holtzman has put out a proposal to upgrade the slit-viewing
camera, to improve read-out time (and the need for time-consuming
darks) and to make it remotely operable. This would greatly increase
observing efficiency, especially for short exposures/bright objects.
Jon is asking for money from the observatory (~$10K) to buy the
instrument. Check out the proposal at
http://ganymede.NMSU.edu/holtz/slitview/
We are enthusiastic about Jon's proposal.
****************The future of vBNS********************************
vBNS, which supplies the high-speed internet connection to the
observatory, is vanishing at the end of March. This will remove the
high-speed access we've been enjoying for the last 1.5 years. This
may take us back to bad old days when connectivity was the limiting
factor for remote observing. All institutions, with the exception of
Princeton, will be going over to Abeline (although this needs to be
confirmed), which is the vBNS successor. NMSU has left-over vBNS
money to get Abeline. In a year, it is unclear where this is going;
if NMSU drops Abeline at that time, then everyone will be in trouble
again, as both ends of the internet connection must be connected to
Abeline in order to receive the full benefit.
We discussed the possibility of leasing bandwidth for connections
between nodes of a geographically spread "private wide-area network", this
could be of order $1.5 K per month per institution.
We briefly discussed a face-to-face meeting, in which the major
issues facing the observatory (aka, the next three-year plan goals)
could be hashed out. This will be discussed further in future User's
Committee meetings.
No corrections to last month's meeting minutes.
The next User's Committee meeting will be held on April 3 at 11:30
AM East Coast Time.
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