Subject: APO 3.5m User's Committee meeting, 4/10/00

From: strauss@astro.Princeton.EDU

Submitted: Fri, 14 Apr 2000 09:45:45 -0400 (EDT)

Message number: 428 (previous: 427, next: 429 up: Index)

  Apache Point Observatory 3.5m User's Committee Meeting
		April 10, 2000

Attending: Jeff Brown, Lew Hobbs, Jon Holtzman, Ed Turner, Michael
Strauss, Bruce Gillespie, Chris Stubbs

Recent results from and future plans for engineering time

Stubbs: The engineering nights have been used to tackle two major
issues: (1) Time-varying astigmatism due to something binding up on
the primary.  (2) Instabilities in the secondary mounting structure is
causing image jumping around.  On item (2), one of the 3 mount-points
(Actuator C) of the secondary is defective; we're going to fix that
this week during shutdown; it is not clear whether its the flex pivot
or the piezos that's the problem, but we'll get it fixed.
[Update: We have found 1, and maybe 2 broken flex pivots; they are
being replaced.]

The primary mirror problems are adding 0.2-0.3" in quadrature to the
seeing; this is not as serious, so it's somewhat lower priority.  It
also seems to be getting better (although no-one knows quite why).  In
mid-May, we might use engineering time to track this down. 

Plans for upgrading DIS

(1) We want to replace the slit-viewing camera; Jon Holtzman is taking
the lead on this; this should be completed by June. 
(2) We want to replace the current detectors with modern 2Kx4K
detectors (which is what we have in house)
(3) We also would like to get improved optics.  The design of the current
optics says that the images should be quite good.  But we haven't seen
such good images in practice: is this due to poor alignment, or poor

Everyone is very happy with the idea to get the upgraded detectors
into the instrument as soon as they are ready.  Much enthusiasm all around.

  Turner: There have been some problems with the way people indicate
which of the DIS gratings they want to use.  If you're going to use
only one, *please* let the observing specialist know this as *early*
as possible; changing these things in and out is a labor-intensive
activity.  Please do not specify a second grating in your observing
proposal if you don't need it!  An idea: Why not put the third grating
in the current slot for imaging mode?  A question: how many people
actively use imaging mode for DIS?  It is useful for those doing
multi-object spectroscopy (although no-one is actively doing this
now); none of us were aware of any other programs carrying out DIS
imaging observations.

  Holtzman is now ordering the upgraded slit-viewing camera, and hopes to
have it in hand by late May. 

  Turner would like schedulers to do sanity checks on the proposals
sent in, for such things as the DIS gratings (see above), and
inconsistencies on the dates requested.

Visitor Instruments:

  Sean Casey's InSb near-IR camera was on the telescope in the last
month.  It will still be a long way before it is user-friendly and
remotely useable; it requires a number of people on the observing
floor to keep it running.  There is interest in upgrading it to make
it into an integral field spectrograph.  This instrument has a field
of view of 37" (tiny pixels).

  Bernie Rauscher says one could buy a MerCadTel array and electronics
off the shelf to upgrade GRIM to something competitive: lower-noise
and better sensitivity (although still 256x256).  It would cost of
order $100K.  It would not be very difficult to switch this in.

  In one week, LLNL is bringing an instrument to the mountain: A
Fourier Transform spectrometer, working in the optical (but with
proper detectors, could be work in IR).  It could live at APO for an
extended period of time.  It fills the same niche as the Goddard
Fabry-Perot instrument.  We had a brief discussion of which of the two
has better performance; there is little conventional wisdom on this,

  Movement is starting to happen on the new topend; it could conceivably
happen as early as this summer. 

Training list of people certified to use the telescope remotely:
  It has been updated recently based on feedback from the User's
Committee.  Gillespie and Turner are still considering a policy about
how long one stays on this list without a visit to the mountain or
observing remotely. Strauss will send e-mail to all those people on
list who are not on apo35-general, to find out whether they are still
active users. 

  Two free nights are available for Target of Opportunity observations
(SDSS and otherwise). Demand for these has not yet been overwhelming.

  No corrections to last month's meeting minutes.

  The next User's Committee meeting will be held on May 8 at 11:30
AM East Coast Time.

APO APO APO APO APO  Apache Point Observatory 3.5m  APO APO APO
APO  This is message 428 in the apo35-general archive. You can find
APO  the archive on
APO  To join/leave the list, send mail to
APO  To post a message, mail it to