Subject: APO 3.5m User's Commitee meeting, 5/8/00

From: strauss@astro.Princeton.EDU

Submitted: Mon, 15 May 2000 17:47:48 -0400 (EDT)

Message number: 434 (previous: 433, next: 435 up: Index)

  Apache Point Observatory 3.5m User's Committee Meeting
		May 8, 2000

Attending: Jeff Brown, Lew Hobbs, Ed Turner, Michael Strauss, Chris
Stubbs, Bruce Gillespie, Rene Walterbos

 Not attending: Alan Uomoto

Accomplishments of the April shutdown:

  Worked on mounting of new secondary.  Various parts were replaced
and tests carried out.  A few engineers who are working on the new
topend came to the site, and were able to see the details of the
current system.  Things appear to be better, but there are problems
with image motion that started appearing over the weekend.  Problems
Might these be due to water in the PMSS hydraulic lines?

  May shutdown plans (May 15-18) are described in the appendix below
(from Mark Klaene).  
There may be work both on baffling and on the DIMM, by Chris Stubbs
and his team.  They will be using an instrument that measures rapid
image motion, to determine what is causing some of the problems we've
been seeing recently.

  July shutdown (July 10-28) will focus on work on the astigmatism on
the primary mirror, as well as service work on the bearings of the
telescope.  See the appendix for the list of topics to be addressed at
this time. 

  The status of the new topend: There are a lot of resources in place
at the site, UW, and UC, but there needs to be some coordination of
the various people.  There is a plan to go ahead and order the square
truss for the end of the telescope, to get things rolling.  

  Right now, the secondary is held up with steel rod tubes under
tension, as opposed to the traditional metal vanes.  It is not clear
which should be used for the new top end. 

  There is a phone con tomorrow to make decisions of which ports each
of the new instruments planned (in particular, Chris Stubbs'
wide-format camera, and the laser for Chaos) will go.  There is a fair
amount of engineering details to go through to get this straight.  To
permanently mount an instrument at a non-Nasmyth port gives very good
efficiency, but then you needed a dedicated rotator and guider, an
additional $50 to $100K expense.  If we hang too many instruments on,
it is possible it will cause troubles with the telescope drives. 

Stubbs: this ties directly into questions of the long-range plan for
the telescope.  Therefore, it would be very good for the user's
committee to put together a straw-man five-year plan for

Gillespie: If we could get a rotator in place, we could put GRIM onto
a non-Nasmyth port right now.  Stubbs is thinking about switching
rotators between what he's building for his large camera, and the
current one at the Nasmyth port.

Gillespie will get center of mass and inertial parameters for the
existing instruments, information necessary to understand the
specifications of the rotators we would need to get. 

Observing efficiency enhancement effort: We are thinking about using a
tool from the SDSS folks whereby you can clock how much time you spend
doing different activities, to see where overheads are going.  This
would be very useful to figure out which items can be tackled to try
to improve efficiency. 

Director's Discretionary time for SDSS and other follow-up is getting
used; 5 or 6 proposals were received, and four half-nights were
assigned this quarter.

Strategic plan for the 3.5m once the SDSS finishes (roughly 5 years
from now) is something that we should start thinking about now.  The
issue is that there are a lot of people on the SDSS payroll who are
taking part in 3.5m activities (some of whom are split 50-50 between
the two projects).  Moreover, there are a lot of fixed operating costs
on the mountain (plowing the road to the observatory, the phone
system, etc), which the 3.5m would have to take on by itself.  We need
to maintain a critical mass of people and expertise on the mountain;
without the SDSS, this will all become more expensive.  Should we go
to much more austere operations?  Should we make this a more
specialized (as opposed to general-purpose) telescope?  This is an
issue for all the participating institutions to start thinking about.

Stubbs: DIS upgrade: we're going to leave the existing optics, and
replace detectors and electronics.  We will not buy off-the-shelf
electronics (which was the initial plan); rather, we'll borrow from
electronics of the wide-field camera.  We're talking to Alan Uomoto
about a SITE detector on the blue side; the red side will use a chip
available at UW. 

  No corrections to last month's meeting minutes.

  The next User's Committee meeting will be held on June 19 at 11:30
AM East Coast Time.


From Mark Klaene, May shutdown plans. 

1. repair rotator runaways (R&R motor?) (daytime 1-2 days JD,MK,DW)
2. drop vent tubes 1/2" to see effect on astigmatism and high freq
   oscillations (1/2 night all)
3. S-H dat on full altitude sweep ( 1/2 night Jeff M)
4. further 2dry  testing TBD  (1/2 night JD and Jeff M)
5. Install datec monitor for PMSS  (daytime peter D and Dave woods)
6. mirror cell warping test TBD   (daytime  JD and Tim Rennick)
7. fast guiding metrology testing  (3/4 night)

From Mark Klaene: Tasks for the July shutdown: 

pull M1
repair hardpoint dimples
Wash M1
remove perimeter seal
install encoders on M1 and perhaps M3. 
clean up PMSS wiring
service main  az bearing
cont work on mirror cover automation

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