APO 3.5-m Users Committee Phonecon, 3/8/04 Attending: Ed Turner, Michael Strauss, Bruce Gillespie, John Bally, Fred Hearty, Don York, Russet McMillan, Bruce Balick, Karl Glazebrook, Al Harper, Rene Walterbos Absent: Jon Holtzman Minutes taken by Bruce Gillespie ********************************** Telescope/Instruments Report: Bruce G and Russet said that the telescope has been performing reasonably well lately, and hasn't suffered from cold-weather problems recently because the weather has been milder. The need for routine engineering work has increased somewhat since we have been clouded out during recent scheduled engineering time. The facility instruments are largely working. The echelle guider camera has a loaner controller to see if the occasional crashes go away. GRIM2 still has the missing quadrant problem once in a while. DIS blue camera has some low-level noise pickup that has defied diagnosis so far. SPIcam's control computer died, and a somewhat cobbled replacement system is now running it; a new ICC is being ordered. ********************************** 10th anniversary celebration: Rene mentioned that we still need speakers for science talks at the workshops on 27 and 28 May, and we also still need invitee lists from most of the institutions. ********************************** Integral Field Spectrograph proposal: John Bally reported that he hasn't heard any reaction from CFHT about their potential interest in the IFS. He also is waiting for feedback from potential users at CU. Bruce Balick reported that Connie Rockosi polled the UWash users, and found that they would "very, very much" like to use an IFS at APO, especially for spectroscopy of extended galaxies, halos, etc. They note that the instrument would likely need bigger lenslets to reach the sky limit, probably ~3 arcsec. An alternative would be to use fibers, say 300 for 3 arcsec apertures, or 1500 for 1.5 arcsec. In any case, grating selection is going to be tricky. There are concerns about the CFH detector characteristics, e.g., CTE. Michael Strauss reported that the Princeton user community thinks that the extragalactic science opportunities are great. They are concerned, however, about the small throughput of the proposed system using small lenslets; the small lenslet design would mainly be useful only for emission line objects. Also, they anticipate problems in optics design and manufacture. Rene reported that Jon Holtzman found that the NMSU interest in the IFS would comprise about one-quarter to one-half of the NMSU use of the telescope. For example, Rene would like to use it for emission-line work, especially at low spatial resolution. John Bally pointed out that the detector pixel size drives the lenslet size. Karl Glazebrook noted that you could bin the detector pixels so that the lenslets could be bigger. John Bally added that one could use a fiber-optics front end to get large input pixels. Al Harper noted that the size of the grating would be dependent on A-omega constraints. Bruce Balick said that the IFS would be great for the kinematics of disks and halos, and clusters. Don York emphasized that the instrument must be able to reach the sky limit to be widely useful. Bruce Balick reminded us that we need to be careful to define the unique niche this instrument would fill on a 3.5-m telescope, given the competition. He feels that the low-surface brightness, large input pixel, projects would be that niche. Al Harper then noted that such an instrument would have a spectrograph as large as the ones built for 6-m and larger telescopes. Bruce Balick said that a reasonable way to fund such a huge instrument would be to grant wide community access, ala TSIP. Given the huge estimated cost, does it make sense to build a new detector instead of using the CFH12K? John Bally thought no, because a comparable new detector would be very expensive compared to the CFH12K. Bruce Gillespie noted the similarities in IFS to the proposed WIYN 1-degree camera, where the expected instrument costs are comparable to the initial costs of their respective telescopes, and both filling a niche that only 4-m class telescopes can serve. John Bally discussed some of the possible reasons why existing IFSs have not been particularly productive, citing software complexity, limited detector size, and data-cube analysis problems. Al Harper said if you're going to require that the instrument be usable to the sky limit, you will need to have optimal detectors. Karl Glazebrook said he had sent a technical memo to John Bally about the IFS, and that he had not yet received any comments from the JHU users on the proposal. Don York suggested we consider building it with a "dial-able" set of entrance apertures, which was endorsed by John Bally. John also said that he hadn't heard anything from Bruce Woodgate, who has expressed interest in the IFS in the past. Al Harper also said that he hadn't heard any feedback from the UChicago users, and he will poll them again. There will be an opportunity to discuss this at Chicago on 17 April during a local users community meeting. Ed Turner summarized the highlights of this discussion: There is the issue of reaching the sky limit which may be achieved by using larger entrance pixels, and/or pixel binning on the detector. Another issue is whether or not to use the CFH12K, or to plan to build a new detector. The availability of the CFH camera is TBD anyway, so we should have a plan to build a new detector as backup, anyway. Don York added that he could argue for the smaller pixels, e.g., the "red rectangle" and for galaxy spectra without contamination. One question is how efficient the spectrograph needs to be--is the typical 20% throughput good enough, or do you need to optimize the spectrograph for high throughput in a limited observing mode. Ed Turner finished off by saying that we need to hear from CFHT about their interests, and that we should get a better guess at the total cost of the IFS before we invest too much more effort in the technical design. John Bally said he would talk to CFHT, and that he would post a new version of his white paper with updates reflecting these discussion. ********************************** CorMASS is coming (really): Bruce Gillespie again reminded the user community that the low-res NIR spectrograph CorMASS is coming to the 3.5-m this spring, with commissioning runs now definitely scheduled for 3 - 7 May. If users are interested in any tests or science commissioning experiments during this run, they should contact Bruce Gillespie (gillespi@apo.nmsu.edu). More information on the capabilities of CorMass will be posted soon. ********************************** New Instrument Call for Proposals: Ed is preparing a CP for a new ARC instrument for the 3.5-m, which will have provisions for significant CIF funding support, plus an allowance of Director's Discretionary time for commissioning and science programs. The proposals would be due this summer, with a late summer decision likely. The CP will probably be issued within the next few weeks. ********************************** NIC-FPS report: Fred Hearty said that the engineering detector and controller would be going into service fairly soon, after they solve the problem they've encountered with cool-down rates. The etalon mover is being build, and they will be testing the IR etalon this week. The filter wheels are in test, and the dewar has passed its deflection tests. The overall delivery schedule is unchanged, and they are working on a commissioning plan, and expect a turnover to APO for user science programs by 1 Oct 04. ********************************** Last month's minutes were approved without comment. Next phonecon will be on Monday, April 19, 2004, at 11:30 AM Eastern Time APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 753 in the apo35-general archive. You can find APO the archive on http://www.astro.princeton.edu/APO/apo35-general/INDEX.html APO To join/leave the list, send mail to apo35-request@astro.princeton.edu APO To post a message, mail it to apo35-general@astro.princeton.edu APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO APO