Apache Point Observatory 3.5m User's Committee Meeting April 15, 2002 Attending: Bruce Gillespie, Ed Turner, Michael Strauss, Lew Hobbs, Jon Holtzman, Rene Walterbos, Chris Stubbs, Alan Uomoto, Bruce Balick, Jon Morse Agenda: o DIS upgrade status and plans o NIC-FPS PDR report o Summer shutdown plan o Other CIF projects status o WIYN 1-degree imager workshop *************** DIS upgrade status and plans *************** The new DIS chips and electronics are in place, and the instrument has now been used for science by a variety of groups. As reported earlier, one of the lenses on the blue camera has the wrong coating. A new lens has been ordered, and will be installed April 24-26 (during bright run). At this time, we will also install an electronics upgrade that allows synchronous readout, and will improve readnoise properties. At that point, the first phase of the upgrade will be complete. Stubbs: there is one other feature is not yet understood. Every once in a while, there is a bias jump on some rows; it comes out with row-by-row bias subtraction. We'll keep an eye on it, and see if we can diagnose the problem. The next step will be improvements in optics, which will improve sampling and vignetting. This work is planned for the summer shutdown. There is a possibility also to fix the infamous throughput problem, i.e., the non-transmittal of light below 3850A, at the same time. There has not been much feedback from the users about the new DIS. Erika Ellingson says that she is able to go significantly deeper than she was able to before. But please broadcast your experience (to the mailing lists, or to Ed Turner, Chris Stubbs, Jon Holtzman, and Jeff Morgan), so that we know what works and what doesn't. *************** NIC-FPS Preliminary Design Review report *************** Jon Morse at Colorado is PI. Jon Holtzman, Bruce Gillespie and John Barentine of APO attended the PDR meeting. The PDR was successful and productive. The CDR will be mid-summer. The biggest question is the choice of detector. The standard choice was a new Hawaii Rockwell 1K chip. It is quite expensive. Raytheon has been promising a similar product for some time, but they only have test units thus far, so this would be quite a risky approach. So the decision was to go ahead with the newer version of the Rockwell Hawaii chip. This will afford better read noise, higher QE, low latency, and sub-framing than the older Hawaii chip. Gillespie: Filter choices were discussed. The baseline filter set is 5 filters (J H K_s, and narrow-band filters at Fe II 1.64 microns and H_2 2.12 microns), but the current design can hold 18 filters in the filter wheels. There have been quite a few suggested filters to add from the ARC consortium, more than there are slots available. -How will we pay for these additional filters? They are not cheap, and only the five baseline filters are budgetted at the moment. -How do we decide on which ones we need? -Do we want a third filter wheel? This is possible, but will add considerably to the cost of the instrument, and delay the optical design. Can the Fabry-Perot replace the narrow-band filters? Not really, because the FP has R = 10,000, and needs a 0.5% NB filter in concert for order-sorting. Can we get discounts for the filters by bulk-ordering with other observatories? Note that GRIM will stick around along as it stays alive (i.e., it will not be retired once NIC-FPS comes on line), so all the filters that are currently available will continue to be available. There was some discussion about whether one needs a shutter with this instrument, and how one might read out the chip (without a shutter) in such a way that there are no gradients across the field, and that added noise is kept to a minimum. Which readout rates are desireable? Morse will post details about the instrument on the web soon; this will be announced to apo35-general. ******************** Summer shutdown plan ******************** Planning is underway for the summer shutdown. The tentative dates for the shutdown are July 15-August 30, which is longer than normal. The big items will be a realuminization of the primary and repairing the shutter motor drives. ******************** Other CIF projects status ******************** Uomoto has put together a description of a low and medium infrared spectrograph, optimized for point sources (a slit 30" long), available on the web at: http://annabel-lee.pha.jhu.edu/Irspec/RefBook/book1.html This instrument will be built by Alan and his team in collaboration with the University of Chicago. They plan to use an "old" Hawaii chip. They plan to get the instrument on the mountain in mid-2004. Alan emphasizes that this is a straightforward instrument; there are no show-stoppers or particularly difficult items as potential schedule-breakers. Stubbs and York are discussing the possible use of chips that Chris Stubbs has available for an upgrade to the echelle. **************** WIYN 1-degree imager workshop ****************** A workshop was held at KPNO last week to discuss a next-generation wide-field imager for WIYN. As Stubbs emphasized, with our f/10 focal plane, it is difficult to rationalize building a wide-field imager at APO, and so the possibility of collaboration with WIYN is quite attractive. Gillespie and Doherty went to the workshop. The plan is to build a 32K square imager, with a 1 degree field of view. The timescale for first light would be of order 5 years from now. They have identified a number of science drivers; we may be able to help them with identifying further drivers (such as star formation studies). The last meetings' minutes were approved. The next meeting will be held at 11:30 AM EDT on May 13. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 567 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