Subject: 05/19/03 APO 3.5m User's Committee Meeting Minutes


Submitted: Sun, 25 May 2003 13:55:22 -0400 (EDT)

Message number: 673 (previous: 672, next: 674 up: Index)

		APO 3.5m User's Committee Phone Conference
		    May 19, 2003

Attending: Ed Turner, Alan Uomoto, Bruce Balick, Jon Morse, Bruce
Gillespie, Rene Walterbos, Mike Shull, Don York, Al Harper, Stephane
Belande, Chris Stubbs, Michael Strauss

************The Status of NIC-FPS
Jon Morse: Rockwell, who is supplying both the engineering chip and
the control electronics, is running late.  They have had to redesign
some of their electronics, which has fallen behind.  We were supposed
to get delivery by mid-April; it now looks more like July, but we told
them that we're poised to take delivery of focal-plane assembly at any
time.  So we can work with the chip, even without the electronics.
They should be able to deliver engineering chip alone by the end of
May.  The science-grade chip may arrive closer to July.

  The optics have arrived from Janos.  Some of the retaining tabs
holding the lenses in place in the collimator look bent (!); it looks
like the assembly had been dropped in shipping.  It will be sent back
to fix this problem; it will be hand-carried back to Janos in Vermont.
These lenses are not on the critical path.  The camera itself looks

  All the dewar parts are here; assembly is starting. 

  Filter wheel mechanisms are designed and assembled; testing is
starting.  Motors are on order.

*************Observing Software:
    Russ Owen and Craig Loomis have been working for some time on a
Python-based replacement for Remark, which could work on multiple
platforms.  The software, TUI (Telescope-User Interface) has
successfully been used to observe; however, it does not yet have all
the instruments incorporated in.  The DIS interface in particular
still needs to be done, which will be about 2-3 person-months of work.
Once it is commissioned, it will need to be tested properly at each

*************Last week's shutdown
  We had a planned shutdown last week: it was to repair enclosure drive and
shutter mechanisms.  It went quite well; see the summary by Mark
Klaene in apo35-general #671.  Jon Davis said that
everything intended to be accomplished was accomplished.  The mountain
staff also worked on the DIS electronics in collaboration with Jeff
Morgan and Peter Douherty, and the recently reported enhanced noise
seems to have gone away.  Hooray!  In particular, both the noise
spikes, and the low-amplitude pattern noise seem to have been
eliminated.  It was "just" a matter of finding the proper grounding. 

************More news on DIS
  There are two major concerns with the throughput of DIS.  The
dichroic splits the light to send to the two cameras at a wavelength
of about 5500A.  However, the coatings of the optics in the DIS II
cameras assume a split at about 5300A; the blue camera in particular
transmits very little light redwards of 5300A.  This means that the
200A stretch from 5300 to 5500A is very poorly detected with our new
system.  We discussed whether it makes sense at this point to replace
the dichroic, to more accurately match what the cameras deliver.
There is a possibility that the UV throughput problem we've had from
day one in part is due to a bad coating at the dichroic; if so, fixing this is
a possibility as well.  Replacing the dichroic would not be terribly
expensive either financially or in terms of the time required to do

  There is a separate concern about throughput: Jon Holtzman has
consistently been finding a throughput across the wavelength coverage
that is 10-20% lower since the optics upgrade.  The cause of this
remains unclear, and is continuing to be studied. 

****************Echelle guider: 
  The echelle guider has now entered service, and is working well.
Remember that it guides on the light spilling out of the slit on the
object in question; because of field rotation, one can't guide on
objects off the slit jaws.  Anecdotally, people have had no problem
guiding on 13th mag objects through clouds in 20 sec exposures; 16th
mag should be fine in good conditions.  There is still a sense that it
does not guide as efficiently as does the DIS guider; York and Stubbs
will discuss this.  York: many thanks to the folks on the mountain for
their work on this!

  Gillespie: Work on baffling and cateye mask are continuing; the
metal is being cut now.  We're now weeks away from installation!

   Harper: the double images seen on some earlier GRIM runs may be due
to a focus problem: when the telescope goes out of focus in good
seeing, astigmatism makes it look like double images (if you're out of
collimation).  Keeping the telescope in critical focus is quite a
chore.  Russet would make corrections between images, so this
double-image problem would appear to come and go.

  Following the focus is the limiting factor in image quality.  What
we really need is an auto-focus capability, especially in the near-IR.
The problem is that hysteresis in the secondary means that we can't
focus during exposures.  The new topend will address this.

  There is a Board of Governor's meeting coming up.  A fair fraction
of the present group will be there.  The focus of the meeting will be
on long-term plans for the telescope.  As representatives of the APO 
user communities at each institution, we need to make sure we have
received input from our institutions about the future directions we'd
like to see the observatory go. 

  Rene Walterbos has sent around a memo describing the
agenda/questions that will be discussed at the meeting; you can find
them below. Anyone should discuss these issues with their
representative at this meeting.

  Last month's minutes are approved. 

  Next meeting to be held on Monday, June 16, 11:30 AM EDT. 

*********Appendix: Memo from Rene Walterbos describing the questions
to be addressed on the future of the APO 3.5m:

Each institution will be asked to make a brief presentation on their
viewpoints regarding a number of issues. These presentations will take
place in the morning of the Tuesday Board meeting.

It is important that the presentation advocates the institutional view
point, not that of any one or a few individuals. Therefore, we
encourage discussion of these issues with your department members.

1. What are your institution's major goals for involvement with the ARC
3.5-m telescope? Possible topics may include: particular (large)
science projects to pursue; educational objectives, such as graduate
student training; facility to test and develop instrumentation or
pursue other programmatic priorities; or general purpose 3.5-m
telescope with broad-based instrumentation.

2. Would you like to see your institutional share of the 3.5-m
telescope increase, decrease, or maintain at the current level?

3. What would drive this choice? For example:

- a larger share of the telescope time going to a few dedicated large
projects might be appealing to some, less appealing to others.

- increasing funding levels to improve instrumentation might make a
significant difference in the competitiveness of the facility and the
science it can do. Would your institution be willing to support this,
or should we look for new members if we need to go this way?

4. If the future of the SDSS requires significant blocks of 3.5-m
follow-up, would this be an issue or would you support such a
direction if that would be one or a major way to make the future of
one or both projects viable? Even if instititutional shares are not
affected by this (e.g. for non-SDSS participants), it could still
drive the future instrumentation or other support for the 3.5-m.

5. General issues regarding ARC and APO:

- Does the structure of ARC set up almost 20 years ago remain viable?

- Should ARC actively try to recruit new members. What should be the
main motivation for doing this (e.g. new projects, financial
resources, etc)?

- Should we actively pursue location of other facilities on the
mountain under certain circumstances, for example to offset site
operations cost, or should ARC stick to its initial concept and
operate only its own facilities at APO?

6. Other issues you would like to discuss regarding ARC and APO.

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