Subject: APO 3.5-m Users Committee minutes 12/20/04

From: Bruce Gillespie

Submitted: Mon, 31 Jan 2005 13:21:38 -0700

Message number: 888 (previous: 887, next: 889 up: Index)

 

                       APO 3.5-m Users Committee Phonecon, 1/24/05


Attending:  Suzanne Hawley, Michael Strauss, Russet McMillan, Karl 
Glazebrook, Bruce Balick, Bruce Gillespie, Don Lamb, Rene Walterbos, 
Fred Hearty, John Bally, Al Harper

Absent: Don York, Jon Holtzman

Minutes taken by Bruce Gillespie

**********************************


Gamma-Ray Burst Targets-of-Opportunity observing plan:

There was a lengthy and largely concordant discussion of the proposed 
plans and policies for ToO observations of GRBs using the 3.5-m 
telescope during the current and upcoming quarters. The basis for this 
was a straw-man proposal submitted earlier to the committee by 
Suzanne. The Users Committee gave strong support for this use of our 
telescope for this potentially important science, and a decision was 
taken for the interested parties to get together and draft short 
documents describing the science, the observing methods, and the 
recompense policies in order that the observing plan can be explained 
in detail to the larger ARC user community. Some details of the 
discussion follow; the ARC GRB users were asked to follow up on these 
and other details and produce the requisite documents.

Since one of the "trigger" parameters of our plan is the optical 
brightness of the GRBs, Karl Glazebrook asked if anyone knew what the 
V-magnitude limit of Swift is. Don Lamb said that the stated prelaunch 
limit is V=24. He said we don't yet know the in-flight limit yet, and 
noted that the commissioning of Swift has become complicated due to 
more of its instruments coming on line, which has reduced the current 
observing efficiency. Don does not expect us to see rapid reports of 
GRB locations until after ~1 April.

In Suzanne's proposal, there is no plan to observe GRBs in the 
mid-magnitude range (which assumes that Swift and other observatories 
would have this regime pretty well covered). On the other hand, Don 
suggested that NIC-FPS observations of targets in this brightness range 
would be potentially unique, but we should review this after the burst 
alerts start coming in in earnest in Q2. Karl asked what the science is 
for these, and Don replied that NIR observations gives much better 
extinction information, which is uncertain in visible-only 
observations. Most observatories cannot quickly field a NIR instrument 
during dark time, and we can. Also, modeling GRB afterglows is hard to 
pin down if one only has limited-wavelength data to work from. Karl 
mentioned that you also need the redshift, and Don said that others 
will probably get these.

Suzanne's proposal posited an arbitrary 3-hour maximum time limit from 
the alert to commencing ToO observing with the 3.5-m telescope. Others 
countered with a suggested two-day suspense period. Don commented that 
in 2004 he had gotten useful data a day or more after the initial 
alert. Several people thought the <3 hour window would be too 
constraining. This needs to be discussed more.

Karl pointed out that we won't get Swift V magnitudes very quickly, at 
least not early on. We will be getting a finding chart quickly, 
however. Suzanne asked if there would be magnitude information in the 
alert. Karl and Don said not right away. They said if the target were 
visible in the UVOT, we should go to NIC-FPS observing by default, and 
if "bright" we should go to the echelle program. What constitutes 
"bright" and how we assess it in the near term needs to be discussed.

Suzanne then asked for comments on her proposed policy for half-night 
recompense to the interrupted programs, and requirements for data 
reduction and publications on rapid timescales. Michael Strauss said he 
like them "a lot." Bruce Balick supports the proposed program, and 
asked for short documents that outline the science, observing methods 
and protocols, and payback to the interrupted observers. Suzanne 
pointed out that currently UC and JHU have identified 4 half-nights in 
the Q1 schedule that are available as payback to interrupted observing 
programs. The typical GRB observing program is thought to last at least 
2 hours. Fred Hearty said that NIC-FPS could easily get two complete 
photometric sequences of a GRB in that time. Don agreed, and thought 
that the longer exposures would be better with NIC-FPS, and that 2 
hours should do it. He noted that pre-empted observers would often 
still get most or some of their scheduled observing on the night of the 
alert, and would then get more compensation in the payback time. Bruce 
Balick observed that he still needs documents to inform the users 
because regardless these pre-emption episodes are going to be complex 
and cause considerable inconvenience to the regular observers. Suzanne 
agreed, and said we must have the documents that detail the ToO program 
available to the whole ARC user community.

Suzanne then asked for comments on publication limits (first 90 days - 
ARC only). Bruce Balick thought it was a good policy, and Michael 
seconded this opinion. Bruce Gillespie added that if the astronomer 
needed more time for some compelling reason, he could ask Suzanne for 
an extension, as is done with HST proprietary data periods. Suzanne 
said that she wanted the 90-day "ARC-only" period so that the GRB 
science can highlight ARC and the 3.5-m telescope, as opposed to us 
being the umpteenth author on a series of multi-observatory papers. She 
also said that in recent meetings with other observatory directors, it 
was not apparent that other observatories are capable of, or planning, 
any large-scale coordinated GRB observing programs. We could be the 
only semi-organized group, and this may be to our advantage. Bruce 
Balick thought this was great (for us), and plays into our unique 
"niche" potentials being discussed within the ARC Futures 
Committee. Don Lamb observed that his HETE2 GRB observations have 
clearly demonstrated our unique capability to do this. Bruce Balick 
noted that the original observing paradigm for the 3.5-m telescope was 
similar to that used by the Mayall 4-m at KPNO. These new kinds of 
fast-attack queue observing programs break the tradition and will need 
to be carefully "sold" to the general user community.

Suzanne pointed out that, in effect, these ToO programs were activated 
at the beginning of the current quarter, but haven't yet been 
implemented because the Swift alert system is not yet ready. Michael 
Strauss said that we'd better get moving fast and start selling the 
value and particulars of the program to our constituents. Suzanne added 
that subject to commissioning and early shared-risk observing in Q1, 
NIC-FPS may not be ready for general ToO observing until Q2.

On the question of recompense to interrupted programs, Suzanne stated 
(and others agreed) that the half-night payback should be in "usable" 
observing conditions, since by definition the pre-emption was done 
during usable conditions. Also, if the program being run when a GRB 
alert happens is marked as "time-critical" the ToO will be aborted or 
postponed. Some care in proposal selection and processing will need to 
be done to regulate the appropriate use of the non-interruptable flag.

Don Lamb liked the "usable-night" recompense policy, saying that it 
will help sell the ToO program to the general users. He also agrees 
with the policy of including everyone involved with the GRB program, 
the Observing Specialists, and the interrupted observers, as Co-Is on 
GCN circulars. Fred agreed with this, as did Suzanne.

Suzanne said that a GRB group is forming within ARC with scientists 
from UC, CU, and JHU participating. PU, UW, and NMSU participants are 
welcome to join, and should do so quickly. Users Committee members 
should pitch this to their respective users. All interested ARC users 
should contact Suzanne who will put them on the ARC GRB ToO group 
mailing list. Note that to participate in the program will require an 
approved ToO proposal offering time in recompense for pre-empted 
programs.

Don Lamb mentioned that given the availability of sky, weather, and 
estimates of GRB detections, it is probable that the average frequency 
of GRB alerts we would be interested in is probably ~6 per quarter, or 
one every other week. Fred asked if it were possible to have access to 
all the deep NIC-FPS GRB data to do parallel science. Suzanne said that 
all the GRB data will be made public to ARC astronomers after the 
90-day publication period.

In summary, Suzanne asked the GRB principals to get together and 
produce the documentation requested above, and for the Users Committee 
members to communicate this program to their respective users.

**********************************


NIC-FPS status:

Fred Hearty reported that he, his team, and APO staff, have 
accomplished 7 usable nights of NIC-FPS commissioning in the past few 
months, and that the instrument is being used by a "user" in 
shared-risk mode this week for the first time. There are recurring 
problems with indexing the filter wheels, and a software workaround has 
been devised as the temporary fix until the microswitches can be fixed. 
Also, the dewar doesn't hold a hard vacuum for as long as we would 
like, and we will probably need to take the instrument out of service 
for a de-gassing procedure one day every week or two. This can be 
arranged to be done mainly on cloudy days/nights. The Fabry-Perot 
etalon needs more engineering work and will most likely not be usable 
for science this quarter. If the etalon needs to be removed for bench 
testing, this will not happen before the summer when the filter wheel 
and vacuum problems are addressed.

Suzanne said that at the end of the January observing with NIC-FPS, we 
will decide if the instrument will be available for use (as a backup or 
ToO instrument) outside the blocks of time it is currently scheduled in 
February and March.

Fred admitted that he is late getting the users documentation up to 
snuff, so he offered that he will be personally available to coach 
NIC-FPS users this quarter, both in and out of real time.

**********************************


Engineering Shutdown plans for 2005:

Suzanne mentioned that the Critical Design Review for the "new top-end" 
project will be held at APO in April, and at that time a decision will 
be taken whether or not to install it on the telescope this summer. In 
order to have some flexibility, and to mitigate the problems we have 
had with marathon summer shutdowns in the past, we are planning to have 
three shorter shutdowns this year. We are planning a one-week shutdown 
in June, and two-week shutdowns in both July and August. Besides the 
new top-end, we are going to install new telescope drive boxes, 
realuminize the 2ndary mirror, and do the usual routine annual 
maintenance tasks in these shutdowns. A side benefit of this is that 
there will be periods of scheduled observing time throughout the 
summer, although the short nights and typical weather patterns at APO 
during July and August will make for challenging observing conditions.

**********************************


User feedback on new sunset/sunrise-start/stop protocol:

Suzanne noted that the new observing protocol for sunrise/sunset seems 
to be working well. She wants the Users Committee to talk this up with 
their users and collect any feedback. Rene Walterbos said NMSU supports 
the changes. Suzanne said that she has heard very little, but what 
there has been has been positive. Russet McMillan noticed that there is 
a wide variation among users of who shows up on time, or not.

**********************************


User feedback on early experience with observer auto-notification 
system:

Suzanne asked what people thought of this. Rene said that Jon Holtzman 
likes the new system. Russet commented that for block scheduled 
programs the users get a lot of unnecessary messages, but fixing this 
"feature" would be tricky.

**********************************


Last month's minutes were approved without comment. Next phonecon will 
be on Monday, February 14, at 8:30 AM Pacific Standard Time.

 


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