APO User's Committee Meeting, 04/14/03. Attending: Russet McMillan, John Holtzmann, Al Harper, Mike Shull, Bruce Gillespie, Michael Strauss, Alan Uomoto, John Morse, Ed Turner, Bruce Balick. Not able to attend: Chris Stubbs, Don York, Rene Walterbos Agenda: Instrumentation news: DIS, Echelle, NIC-FPS Telescope news: Baffles, work on shutters Miscellaneous: Weather statistics, Board of Governor's meeting, etc. *******************Instrumentation news***************** DIS installation of new red optics: The work on this is to start today (4/14). There is a danger that it will take a bit longer than the alloted time, which means that people scheduled to use DIS in the days following April 21 have a small danger of losing their time. DIS blue scattering problem: As was reported at the last meeting, it is now clear that there is a component of scattered light in the blue camera, which now seems to have started when the blue side optics were upgraded. There is a guess that this is due to condensation on the blue side. We will pump on that side while the red installation is going on, to see if this cleans it up. New Echelle guider camera: This has just arrived on the mountain. There are some things to be fixed (e.g., some of the cables are not quite long enough), but this should be straightforward. We hope to install it next week, and put it on the sky around April 28. At that time, on-sky commissioning will take place. It may take about 1/2 night; the goal is to get the system in place by the first echelle run on May 10. With this upgrade, the system should allow guiding on 17th (and maybe even 18th) mag objects, opening up the echelle to quasar work. Note that most guiding is done off the slit; the field of view of the guider is small enough (50 arcsec) that there is rarely a field star bright enough to guide on. Echelle ion pumps: These are showing an intermittent indication of trouble. They are working harder than usual and it is not clear why. Over the last month, however, things have been looking better. We have suspicions of either outgassing, or perhaps simply aging of the pumps (which in fact are nearing the end of their nominal lifetimes). It may make sense to replace them during the summer shutdown; we hope that there is no catastrophic failure before then. There are also some concern of an increase in dark current as well, which is due to some cross-talk between the chip and the ion pump; as the latter works harder, the cross-talk increases. Echelle users perhaps should plan to take dark exposures before and after science exposures to be careful. There was a formal review of NICFPS on April 4: Thanks to Bruce Gillespie for putting together an excellent panel of seven people. They heard presentations of the current status and future plans. There will be a written report of recommendations. The panel was quite positive; it was clear that things were going well. Jon Holtzman had sent out a <a href=http://www.astro.princeton.edu/APO/apo35-general/msg.663.html>request</a> for input on the z-band filters (give URL); send Jon any comments you might have. ********************Telescope and Enclosure news****************** The tertiary baffle installation is now complete. One concern was that it would worsen the seeing (due to enclosing air in the tube of the baffle), but we've seen some superb seeing nights since it has been in. But it won't be until the secondary baffle is also in place (still several weeks away) that the scattered light situation will be properly measured, but it should be better already. On a related note: there are long-known asymmetries around the edge of the primary that throw a few percent of the light of the PSF into an extended halo, which can be seen around bright stars with SPICAM. This was taken care of previously by simply masking (i.e., with masking tape) the regions of the primary at fault. However, this mask was removed last August when the primary was realuminized, and so this has been a problem ever since. A more permanent solution, in terms of an easily installed "cateye mask" is being built at Sunspot, and will be ready in a few weeks. There is a 5-night bright time shutdown planned in May to replace worn rollers in the shutter mechanism. The telescope will be completely unusable during that week. This needs to be done in May, not July; it requires having the dome open for an extended period, and we want to avoid rain during this period. ************************Miscellaneous*************************** Russet McMillan discussed weather statistics over the period September 1999 to March 2003; see the summary at <a href=http://galileo.apo.nmsu.edu/~mcmillan/oldweather.html>http://galileo.apo.nmsu.edu/~mcmillan/oldweather.html</a>. Overall, this past February was the worst ever (on the plus side, all the snow received made this the first year of normal precipitation in many years). From Russet's statistics, a global average over several years has shown that the telescope has been closed due to weather only 35% of the time. This of course is not the same as saying that it was scientifically productive for every moment of the remaining 65%, but nevertheless, this is a reassuring number. The ARC Board of Governors will meet at APO on June 9 and 10, to discuss the future of the SDSS and long-term plans for the 3.5m, and the future of the ARC consortium in general. Rene Walterbos will soon send out the agenda for meeting, and points for discussion. Each institution can send up to 3 people to the meeting. Each institution should make sure to have a proper discussion internally of their opinions on these issues. There have been several recent incidents whereby observers were trying to arrange time swaps by going directly to the observing specialists. A reminder: such things should be done through your institutional scheduler and the director. There was confusion on recent programs (especially transient programs): Who is observing? Which instruments? This has led to some wasted time. One possibility is to reinstate a program which was tried last fall: two half nights were scheduled per week for transient science (there's always *something* interesting going on. This program was joint over a number of institutions. Last month's minutes are approved. The next meeting will be held on Monday, May 19, at 11:30 AM Eastern time. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 665 in the apo35-general archive. 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