Subject: Minutes of July 8, 1996 APO User's Committee Meeting

From: strauss@astro.Princeton.EDU

Submitted: Mon, 8 Jul 1996 15:21:35 -0400 (EDT)

Message number: 73 (previous: 72, next: 74 up: Index)

    Minutes of APO 3.5m User's Committee Phone Conference
			July 8, 1996

  Attending: Alan Uomoto, Bruce Gillespie, Ed Turner (Chair), Lew
Hobbs, Julie Lutz, Michael Strauss (taking minutes), Rene Walterbos

Last month's minutes are approved. 

        o Refurbishment of DIS in the fourth quarter of 1996. 

        o afternoon and weekend site support--until 3rd Observing Specialist is
          rehired, need to curtail some weekday and all weekend daytime
          observing support at site (e.g., afternoon cals and instrument setups,

        o secondary
        o project finances
        o data archiving at the site--carryover topic from previous meetings;

o DIS refurbishment: 
  It has been suggested to take DIS out of service for something like
entire 4th quarter, to work on electronics, detectors, optical
throughput.  Alan Uomoto has agreed supervise or manage this effort to
be done by combination of people at JHU and site engineers at APO,
with input from the Princeton folk.  Alan has manpower available to do
this; it would not take effort away from SDSS.  Most of the work would
actually happen on site (see below).  It is not yet clear how to pay
for this.

  Alan points out that most of the work that needs to be done can be
done while the instrument stays on the telescope (especially chip
problems).  The thing it needs to come off for is recoating the
optics, which is at least a three-month commitment of time.
 It remains unclear whether we would get new chips for the camera, as
opposed to improving the existing chips.

  There is also some desire to have another grating to choose from. 

  Alan will write up a detailed plan for the suggested improvements,
to be distributed soon. 

  Most users seem happy to have the instrument taken off for improved
performance.  Don York wants to use DIS over the next year for a
program of following up quasars from FUSE, and he is the only person
who has explicitly expressed concern about the loss of use of DIS for
some period. 

  JHU has plans to build a multi-object spectrograph for APO, but it
is still 3 years away, so there is definitely a need to upgrade DIS in
the meantime. 

  We decided that there will be no formal limitations on DIS usage in
the 4th quarter of 1996.  Uomoto et al will work on the instrument
during this time in ways that do not require it being off the
telescope for lengthy periods of time, and Ed Turner will try to make
a schedule which will maximize the periods in which DIS is not being
used (around bright time).  The refurbishment of the camera optics is
the item which would take the instrument out of commission for a
lengthy period; this is still a program for the future. 

  Telescope will probably be down for 10 days in ~December for
realuminizing of the primary at KPNO (exact dates not yet set).

  We discussed whether it is possible to get the imaging camera built
by Stubbs et al (as a prototype for his wide-field camera in the
works) ready for general use in the fourth quarter.  This remains to
be seen.  This camera will have a filter wheel. 

o Afternoon and weekend site support.

  We are recruiting a new observing specialist (Dan Long has moved
over to SDSS, working days, leaving only two people working nights:
Karen Gloria and Eddie Bergeron).  An advertisement for a replacement
has gone out, applications are starting to come in.  With only two
people on (Karen and Eddie), afternoon support (for calibrations,
remote observing practice, etc.) just becomes more difficult.
Observing specialists come on line at 6 PM, it gets dark at 8:30 PM,
leaving 2.5 hours to do calibrations.  Therefore people are urged not
to insist on needing an observing specialist in the afternoons,
*especially* on weekends. A new person may be on the job as early as

o Situation with secondary.

  Alan: going out for bids on grinding the new secondary (a blank
exists!).  Plan to take existing secondary out during August shutdown
for testing at Steward, but Alan says that it would make more sense
financially for this testing to be done by the same people who will
make the new secondary.  There are rumors from Contraves that
different coefficient of expansion of ribs and front plate for Hextex
mirrors mean that a perfect secondary at the lab doesn't necessarily
mean a perfect secondary in the telescope (if this is really true,
this is quite worrisome for the SDSS primary!  We definitely need to
look into this).  We could test this by doing Hartmann tests on the
telescope at different temperatures.

  Shectman's experience at Las Campanas 2.5m shows that tip-tilt
guiding (driving the secondary) at 10 Hz has caused dramatic
improvements in image quality.  Stubbs is in the process of putting in
this capability for APO.

o Financial constraints:

  There are a number of costly programs in the works; in addition to
the DIS upgrade and the secondary fixes, we have:
  *Fix primary support to eliminate oscillations there
  *Replacement of enclosure wheels
  *Realumination of primary (in December)

  It is not clear where the funds for all of these will come from.  We
may thus have financial constraints on the finishing of these various
projects.  Will probably go to the Board in November to discuss the
granting of further funds for next year to do this.  We should make
sure that our local board members are aware of the needs.

  So what should we put aside for the moment if we're limited
financially?  First priority is enclosure wheels; if these fail, we're
shut down!  (One of the three old wheels is apparently in poor shape,
and really needs to be replaced).  It remains unclear if the new
wheels will not suffer similar problems (Jon Davis should have the
answers), and whose responsibility it is to fix them (i.e.,
manufacturer (L&F) vs. us).

o Data archiving
  Bruce will post some documentation on archiving plans at other
observatories, as a basis for discussion.  Data are not erased until 7
days after it is taken (official policy is actually 72 hours...), so
the problem of data being lost has largely been mitigated.  However,
we could also think about archiving in order to have data saved for
posterity.  At the moment, there seems no strong need for this for the
immediate future. So let's table this issue for the moment.

  Bruce and Ed will put together a draft APO policy document to be
posted on the APO home page. 

Gillespie:  Thanks to all users to site who are giving the mountain 5 days
advance notice. 

Next meeting:
  August 12, 12 noon. 

  On the agenda: 
      Plans for posting technical documentation for APO.

  Bruce will try to get an agenda out the Friday before the meeting.

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