Subject: Minutes, 5/10/99, of APO 3.5m User's Committee

From: strauss@astro.Princeton.EDU

Submitted: Wed, 19 May 1999 12:12:49 -0400 (EDT)

Message number: 349 (previous: 348, next: 350 up: Index)

  Apache Point Observatory 3.5m User's Committee Meeting
		May 10, 1999

Attending: Ed Turner, Jeff Brown, Bruce Gillespie, Chris Stubbs, Rene
Walterbos, Ed Kibblewhite, Michael Strauss, Alan Uomoto, Jeff Morgan

*******************Anniversaries and Science************************
Today is the 5th anniversary of the official dedication of the 3.5m.
Yesterday was the 1st anniversary of the first light for the SDSS. 

There has been a lot of recent science from the synergy of SDSS and
3.5m. Among the discoveries: a z=5 quasar, a distant carbon star, a
series of substellar objects, nearby low-surface brightness
galaxies (this latter not connected with the SDSS), etc.  Science is
happening!  The telescope is now producing roughly 1 publication/week.  

**********Tertiary Rotation Shutdown Report (Stubbs/Morgan)********
Stubbs: The tertiary rotation was motorized, in order to achieve
efficient instrument changes.  This work happened over the last few
weeks.  The UW and APO staff worked well together.  The overhead in
the switching between echelle and an instrument on the other port is
now down to essentially zero.  The motion is very reproducible, with
fields coming back after a rotation to within an arcsec.   There is
still some tests to be done, but things look good.  There is still
also some software integration work to be done; once this is done, the
operators will have simpler operations to carry out the rotation. 

Many kudos for Jeff Morgan and those who worked with him for the
design and execution. Everyone is very pleased.  This was a major
to-do of the 3-year plan.

  The eyelids are not yet automated, but Morgan et al are working on
it.  This will make life easier for the operators. 

  Brown: Can you take echelle lamps while someone else observes on
another instrument?  Answer: No, not yet.  But Craig Loomis (APO) and
Bob Lowenstein (Yerkes) are working on the necessary software
upgrades, and this may be implemented in a few months. 

  Note that at the moment, all the instruments other than the echelle
use the same port, and so switching between them is no faster now than
it was before.  To be able to switch between all instruments quickly
will require equipping other ports with rotators and guiders.  This
will not be cheap.
  During this shutdown, there were a number of upgrades made to the
TCC software, and the echelle was recollimated.  

*************Engineering plans for rest of this year****************
-New secondary
  Uomoto: We may want to pick up mirror from Steward, even though we
don't have the final report from them yet.  The final payment will be
sent once they send the final report.  This would allow us to get an
earlier start on getting things ready for the top-end; there are some
new fixtures that need to be fabricated, so there are several weeks of
configuration work to do. 
 [Late Update:] Jon Davis and Dave Woods are in transit back to APO
with the mirror, and the final report from Steward. 

  Jeff Morgan and others will be working on this soon.  
  The WIYN example shows that a telescope of this type can be
well-baffled, but it is non-trivial.  

-Summer shutdown
Turner:  It will start roughly mid-August, and last for one month. 
			   Goals include:
			   - Installation of new secondary.
			   - Work on skirt of primary
			   - Altitude drive needs to be rebuilt
			   - Aluminization of primary?
			       Need throughput measurements 
			   - Will recollimate the telescope well, after
			   the installation of the secondary, using
			   a new-fangled Shack-Hartman device. 
			   (It would be useful to get a baseline by
			   carrying out such an analysis with the
			   existing system.)
[Late Update:] The Shack-Hartman device is scheduled for delivery and
installation on 20 June 1999. 

-New top end design/plans 
 Kibblewhite: Preliminary design is in place.  The most radical
feature is that the top of the top-end structure is open.  This allows
more room for instrumentation. Ed will be going down to APO to talk to
people there next month about specific issues.

  Idea is to have this built over summer and fall; we need to figure
when it would be good to install this.  Also, does one simply build a
new secondary support unit, or a whole new topend?  We know of
deficiencies with the current topend, so doing everything over could
allow us to ameliorate these problems, perhaps using some ideas from
the SDSS telescope topend.

  Stubbs: This new topend should much improve the mechanical stability
of the telescope, and give us new degrees of freedom to help with
collimation.  A concern: will the topend stay stable when tip-tilt is
working?  That is, will the whole structure rattle?

  All this is going to affect image quality.  So once secondary is in
place, we can figure out what the next dominant term in the seeing
budget is.  We need more engineering monitoring information on the
telescope, to diagnose this. 

-DIS detector upgrade
  Stubbs and Gunn are eager to work together. Stubbs is planning a
trip to Princeton to work with Gunn on this. 

-Visitor instruments
	Woodgate has a Fabry-Perot which he is interesting in bringing
	to APO.  There is modest interest in the 3.5m community in
	using it. 

	Casey has a large-format near-infrared camera. 
	[Late update:] Turner and Gillespie had a telecon with Casey
	and his team; substantial progress was made on arranging
	another test run of the instrument on the 3.5m in the fall. 

	Folks at LNLL have a near-IR Fourier Spectrometer
	   They have this instrument, and are thinking of building a
	   larger version for NGST.  All of incoming photons are
	   detected, and used.

There was a lengthy discussion of the trade-offs involved in getting
visitor instruments, where the telescope time comes from, and the
imperative not to overburden the site staff.

  Stubbs: We have a near-term need for IR instruments; we should
approach the IR heavyweights: Hawaii, UCLA, Ohio State, Florida for
  Don't forget the AOTF instrument, which has a 1024^2 chip. Could it
be made into a more general-purpose instrument? Gillespie is checking
with the AOTF team on this. 

Users report that the echelle is very straightforward to use.  It has
a very small acquisition field, so be prepared with good finding
charts.  Given the accurate reproducibility of the tertiary rotator,
one possibility would be to use SPICAM as an acquisition camera for
the echelle. 

**************Beyond the Three Year Plan*********************

The three-year plan is amazingly on track!  Given that funds will be
available in the outyears for further development, we need plans
for what we want to do over the next three-someodd years.  We'll
discuss this in more detail next time.  Everyone start thinking about
this, and talking to your communities about this. 

  Next meeting:  12 noon, Monday, June 21.

  Previous month's minutes are approved. 

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