Subject: 3.5-m Users Committee minutes 9/17/07
From: Bruce Gillespie
Submitted: Sun, 23 Sep 2007 18:25:14 -0600
Message number: 1058
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APO 3.5-m Users Committee Phonecon, 9/17/07
Attending: Suzanne Hawley, Bruce Gillespie, Mark Klaene, Scott
Anderson, Remy Indebetouw, Ed Turner (for Michael Strauss), Russet
McMillan, John Bally, Bill Ketzeback
Absent: Jon Holtzman, Al Harper, Jon Fulbright
Minutes taken by Bruce Gillespie
**********************************
User feedback, comments from institutional representatives:
Princeton (Turner) - Ed said that Michael Strauss told him he had no
user comments to share. Since much of the time since the last
meeting was during the summer shutdown, we would naturally expect
there to be little user feedback.
UVa (Indebetouw) - Remy had nothing to report, other than UVa is
organizing a site visit for their students this fall. Russet and
Suzanne mentioned that we will be hosting four separate student site
visits at APO in the coming weeks.
UW (Anderson) - Scott had no user comments, and Suzanne mentioned
that Paula Szkody thanked us for getting some guider images of a
target that is scheduled for upcoming HST observations.
CU (Bally) - John had no user comments to report.
JHU (Fulbright) - No report
UChicago (Harper) - No report
NMSU (Holtzman) - No report
**********************************
Discussion of telescope/instruments report - Klaene:
The report is given below; Mark walked through the highlights, and
there was some discussion.
The summer shutdown started and finished on schedule, and the
telescope and instruments are good-to-go for science observations.
Nick McDonald, the recently hired 3.5-m telescope engineer, was given
responsibility for most of the shutdown activities, with help from
several others. Nearly all the tasks were completed (see list
below), and the leftovers will be attended to in the coming weeks.
One of the small scallop cracks in the back of the primary mirror
faceplate seems to have gotten somewhat larger, and as a precaution
the mirror support at that cell has been disabled. No discernible
effect on the optical performance of the mirror has been detected.
The PMSS was serviced and calibrated, and the instruments were all
serviced except the echelle (which is serviced every two years).
There may be a lingering problem with the DIS cryotigers that could
require attention later this year, although they appear stable at the
moment. Except for NIC-FPS, all the instruments (including CorMASS
and GFP) are up and ready for use.
Suzanne recently visited Kitt Peak while our mirror was there, and
she mentioned that the mirror looked pretty good even before it was
realuminized. Mark said that the exact before/after improvement in
reflectivity numbers is not yet available, but there was an
indication that the reflectivity before recoating was ~91%, and only
went up to ~92% afterward. The scattered light from the surface did
improve a factor of 10, from ~2% to about .2%. This indicates that
we are doing a pretty good job of keeping the mirror clean in the
telescope for relatively long periods of time. Russet said that some
observers take calibrations off the scattered light from the primary
mirror, and that they will need to increase their exposure times
accordingly.
The DIS grating mounts were given new larger bushings to help protect
the gratings during changes. Also, the red-high grating has been
shimmed to place the spectrum near the center of the detector.
Suzanne asked if users had been having problems with the red-high
spectrum placement in the past, and Russet said that some users had
mentioned it during instrument checkout, but nobody had reported
problems with data reductions. With the spectrum now better
positioned, the stray light from the on-chip amplifier glow is less
of a problem.
*************************
3.5-m Telescope, Instruments, and CIF Projects Highlights, 8/18/07
through 9/12/07
Mark Klaene
0) Overview
Monsoonal weather continued with moderate rain and evening clouds,
which limited most of the on-sky time that would have been available
for science observing. However, the shutdown started near the
beginning of the reporting period, so little scheduled observing time
was lost. Wet weather continued through the shutdown, but we were
largely able to work around it. Construction started on the SDSS
Support Building expansion project (for AS2) with no disruption to
3.5-m work.
1) Telescope
The shutdown started on time and remained ahead of schedule for much
of the period. Weekend work was performed but limited in scope. To
date all of the shutdown tasks (see list below) were completed except:
o the Echelle fans have not been changed since the wrong parts
were delivered, and
o the new instrument rotator axis controller system was not tested
on the telescope.
There were a few problems noted but none were particularly
surprising. The primary mirror cracks were inspected and were seen
to have stayed basically unchanged except for the top of cell A3--the
load cell for this support has been clamped off to relieve stress at
this mirror position. Loose flex pivots were noted on the tertiary
mirror support and repaired. Fifteen rivets were found to be loose
and were replaced on the primary mirror covers. The mirror covers
were repainted and we anticipate higher overall cal lamp throughput
as well as a noticeable improvement between 350 and 400 nm. The new
instrument rotator assembly was fit tested and aligned but could not
go in to service due to continued work needed on the axis controller
software.
2) Instruments
o The bushings were replaced on all DIS grating holders and the
gratings were realigned. This should reduce the risk of grating
damage when installing gratings, especially in cold weather. The red-
high grating was moved into another mounting cell and a shim was made
to position the spectrum on the middle of the chip;
o Both DIS cameras were evacuated and the cryotiger lines
cleaned. The red cyrotiger compressor was replaced. Contamination
was found in both sets of cryotiger lines;
o SPIcam was evacuated and baked out;
o NIC-FPS remains at CU for 16-channel readout and etalon
upgrades. We expect its return to the site in early October;
o CorMASS was evacuated and cooled down; and
o GFP was evacuated and cooled down.
Summer Shutdown Task List
M3: Realuminize, service actuators
M1: Realuminize, check and photograph cracks
PMSS: Pressure transducer calibration, load cell calibration,
bellofram inspection leak check, air line leak check with belloframs
by sector, servo valves inspection/cleaning, clean mirror cell, vent
tube repair, foam inspection, mirror cover actuator inspect and
service, calibrate LVDTs, investigate fore/aft mirror constraint
Mirror covers: Repaint covers, repair rivets
Pump SPIcam
Pump DIS: Purge/recharge blue cam cryotiger system, install new
bushings in grating holders, remount DIS red-high grating in new holder
Replace UPS batteries: Echelle, Inst - I level, Elect I -level, #3
for ops bldg
Echelle electronics fan replacement (not completed)
New instrument rotator axis controller (not completed)
New NA2 rotator assembly
Repair strain gauge metrology noise issue (not completed)
Replace temperature sensors on primary mirror
Repair secondary mirror accelerometer recording system
**********************************
Wide-field NIR instrument - Hawley, Gillespie:
Suzanne reported that we have received a second proposal from a non-
ARC astronomer (the original proposal was made to us about 18 months
ago) to build a wide-field NIR camera and grism spectrometer with a
13-arcminute FOV and a programmable slit mask, and bring the
instrument to the 3.5-m for their and our use. This could be done in
exchange for telescope time much like the arrangements we have used
with CorMASS and the Goddard Fabry-Perot instruments; other
collaborative scenarios are possible. Several of the Users Committee
members expressed strong support for continuing to pursue this
initiative, and commented on how such an instrument would complement
NIC-FPS and further our interests in general NIR science
capabilities. We need to determine a sense of how much ARC user
interest there would be in having access to this instrument at APO
before expending significant time or money on our side. Users can
check with their committee representatives for additional technical
information about the instrument.
ACTION: Users interested in a wide-field NIR camera at APO should
send a paragraph or two to their Users Committee representative with
copies to Suzanne and Bruce with an expression of interest and/or
questions regarding this proposed instrument.
**********************************
NIC-FPS status - Bally:
John reported that the NIC-FPS etalon has undergone multiple cryo
cycles, and that the oscillations seem to be cured. However, an
accident happened two weeks ago involving the power supply and etalon
motor controllers, which resulted in the need to replace the
controllers, which will cause a delay in returning the instrument to
APO. Suzanne said that a new Q3 schedule, sans NIC-FPS, will come
out shortly, and NIC-FPS will not be listed as available in Q4 until
20 October. The replacement controllers have been received in
Boulder, and the instrument will be bench-tested with the 16-channel
detector upgrade and etalon in a few days. The science-grade and
engineering-grade chips have been modified to allow the 16-channel
reads, which will enable more efficient observations with Fowler
sampling, and the electronics have been modified to reduce system
noise. Software work is underway both at CU and at APO to process
the 16-channel reads, and to provide quick-look images during
observing without excessive processing overheads.
**********************************
Tertiary tip-tilt decision - Hawley:
Suzanne said that a decision was taken not to include tip-tilt
capability into the new tertiary mirror support system, which is
about to be designed. The decision process used, which seemed to
work and converge well, was to form a committee, solicit user input,
examine existing tip-tilt systems on other telescopes, and look at
existing telescope and site-intrinsic seeing data, to determine if
tertiary tip-tilt should be a high priority for the 3.5-m telescope.
Based on these evaluations, we will make fast guiding and auto-focus
(using the existing NA2 guider) our near-term priorities. If tip-
tilt is determined to be needed in the future, we will employ the tip-
tilt design hooks inherent in the new 2ndary mirror mounts.
**********************************
Science Highlights from '07 - Hawley, Gillespie:
This is the time when we prepare the annual report for the ARC Board
of Governors meeting. One or two science highlights (text, graphics,
images) of one or two pages for each highlight are traditionally
presented in the report and orally to the Board members.
ACTION: We need each institution's Users Committee member to poll
their users and send these highlights to Suzanne and Bruce, not later
than 15 October, for inclusion in the report.
For obvious reasons, we would like to have at least one
representative user science highlight for each ARC institution.
**********************************
Actions from earlier meetings - group
[open from previous months]:
ACTION: Suzanne said that the Users Committee members need to
identify which of their users would be willing to contribute effort
and participate in a telecon to scope tip-tilt for the 3.5-m, and to
communicate their names to her and Bruce Gillespie before 30 July.
STATUS: Completed (see above), closed.
ACTION: Jon Holtzman will investigate and report on the tip-tilt
system at the TNG telescope on La Palma.
STATUS: Completed (see above), closed.
[new actions from this month]:
ACTION: Users interested in a wide-field NIR camera at APO should
send a paragraph or two to their Users Committee representative with
copies to Suzanne and Bruce with an expression of interest and/or
questions regarding this proposed instrument.
ACTION: We need each institution's Users Committee member to poll
their users and send science highlights (since Oct. '06) to Suzanne
and Bruce, not later than 15 October, for inclusion in the annual
report to the ARC Board.
**********************************
Next meeting:
The next Users Committee phonecon will be on Monday, 15 October, at
8:30 AM Pacific Time. The agenda and other materials will be sent to
the committee members during the preceding week.
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