Minutes of APO 3.5m User's Committee Phone Conference Monday, February 10, 1997 Attending: Bruce Gillespie, Ed Turner (Chair), Michael Strauss (taking minutes), Rene Walterbos, Alan Uomoto, Lew Hobbs, Jeff Secker. Jeff Secker is taking over from Julie Lutz as Washington State representative on the User's Committee. Agenda Items: CCD cameras for the Guider and for the Echelle Observations of Hale-Bopp with the 3.5m? SPICam status, future, and user documentation Targets of Opportunity programs New DIS gratings New chips for DIS? Recent Pointing Problems Recent Computer Glitches Continued monitoring of the throughput Instrument issues Echelle/Guider: The 512x512 camera currently in use on the guider is needed by the Echelle people for development of their guider. We will get them a different camera to work with, and so the conflict is resolved. Indeed, the new camera used at Nasmyth, from Photometrics, should be much better. We thus will be able to get rid of the current 512x512 camera from Spectrasource, which is quite poor, by March-ish. With the improved camera, and the improved throughput of the telescope, this new camera should go deep enough to find guide stars at any position in the sky, at any position of the sky. This is wonderful news! The new camera being bought for the Echelle will be compatible with the Nasmyth guider camera, and can be used as a spare. Hale-Bopp: should we be doing anything? Comet Hale-Bopp is currently in the skies; it is perhaps a bit embarrassing that APO does not have any specific plans to observe it. Uomoto: Paul Feldman will be launching a rocket from White Sands to observe in mid-March; it would be good to get spectra at that time (although it is only 15 degrees above the horizon at twilight at that time). Uomoto and Turner will discuss various observing possibilities, including taking images with SPICAM. If people have further ideas about comet observing programs, they should talk to Turner. SPICAM and its status: Documentation is starting to be put together on SPICAM performance, specifications, etc. Walterbos says that one of the NMSU people would be happy to write up a manual, and do a proper throughput study. A filter wheel exists; they are now working on making it controllable remotely. Can users yet ask for SPICAM? There is not yet a hard timetable for when it will be generally available. The plan is that this camera will replace DSC once it is fully commissioned, and it has very similar characteristics (i.e., type of chip, field of view, pixel size, capabilities, etc) as does DSC (more details wait on the detailed documentation to be put together for the camera). Thus observers who wish to use SPICAM for second quarter should indicate on their form whether DSC would be acceptable if SPICAM is not available (and vice-versa). It is not clear whether the chip in SPICAM is thinned. If it is not, then (unlike DSC) SPICAM has very little response in the UV. Tim McKay says that the people at Yerkes might have interest in using DSC there after it is decommissioned at APO. He also points out that the SDSS filter set currently in the DSC are not owned by APO, and will leave with the instrument; we will need to acquire a new set of 3x3 SDSS filters for APO (about $5K). In any case, the filters that are available are documented on the APO Web site. SPICAM takes 3x3 filters; it is not known if it takes 2x2 filters as well. Jim Fowler and Bob Loewenstein are starting to think about developing software to allow SPICAM to be controlled through REMARK. It will still be another year before we start thinking about rewriting the basic observing software from scratch, to replace REMARK. Targets of Opportunity (ToO): Bernie McNamara from NMSU has had in the past used APO for ToO programs. There is definitely precedent for doing this kind of thing; APO is well set up for it, although we don't have any formal policy in place; when ToO programs arise, people simply contact all relevant people (Gillespie, Turner, and the local APO schedulers) and make arrangements as best they can. At the moment, this is happening infrequently enough that it is not causing any major perturbation on the schedule. We agreed that this practice should be encouraged, and briefly discussed whether the observatory should be in the position of actively carrying out the ToO programs (e.g., if someone writes a proposal to take spectra of the next bright supernova to go off, then the observatory would take responsibility for getting those spectra as soon as they hear about a suitable supernova). We realized that it would be preferable to give the PI the responsibility to ask for the time each time a relevant ToO comes up. Of course, the way for these PI's can be smoothed by writing a proposal ahead of time, as it were, warning the Observatory and the Director that if a ToO comes up, they will be asking for time. In the meantime, each User's Committee member will query the members of their institution about interest in ToO programs. DIS grating: There has been interest in getting gratings for DIS of resolution intermediate between the high and low resolution gratings currently in place. Alan Uomoto has been looking into this, and suggests a pair of gratings at 300 and 600 l/mm, respectively. To finalize this will require knowing the details of DIS' optical prescription. Alan plans to buy something off the shelf; when he finds something appropriate, he will present it to the User's Committee at the next user's committee meeting. DIS chips: There is wide-spread agreement that the chips currently in the DIS are about 2 generations too old. They have a high read noise, persistent ghosts, and a variety of other problems. There is an opportunity to get *free* CCDs through an NSF program through Lick Observatory (2Kx2K, 2Kx4K Orbit and Loral chips), although these chips come in wafer form, without any packaging. In addition, they are thick chips, and would need to be thinned. Alan estimates ~$50,000 and 2 years development time would be required to do all that is necessary to get them ready to do science. Full details of this program, which requires writing a science proposal, can be found at: http://gardiner.ucolick.org/~ccdev/ccddist.html. Proposals are due soon (Feb 21)! Alan feels that the development cost and time to get these chips to work is prohibitive, and is looking into the possibility of using chips from the HST Advanced Camera (although those chips have not yet appeared). He asks whether, if financial push comes to shove, we might delay the recoating of the DIS optics to fix the UV throughput problem, in order to use the money ($5-7K saved) to put into the chips. This is not very much money, but it could make the difference. The User's Committee will query their users about this. Pointing problems: Since the shutdown, the telescope has been having a lot of pointing glitches: things will work fine for a while, and then the pointing will be *way* off, and/or images will be trailed. 20-30% of time on those nights on which this is bad is lost. It is believed that this is due to falling behind on maintaining the lubrication on the azimuth encoder.. It is a day of work, plus some nightime effort, to clean these; this is currently planned for Feb 13 (the first half of that night is engineering time). There are related lubrication and wear issues with the altitude drives; this does not appear to be a cause of the current pointing troubles. Recent Computer Glitches: There have been quite a few instances lately in which there has been loss of communication between various of the systems which operate the telescope and the instruments. There are several potential causes: 1. We have upgrated to latest Solaris on MC; there may be some subtle incompatibilities between machines. 2. The system may be becoming sensitive to fragmented disks; all the software could use a rebuilding (which is quite an extensive process; perhaps best done when the observatory is shut down for several days by heavy snow). 3. Finally, it is possible that there are some problems with various electrical connections. All these are being looked into. Monitoring the Telescope Throughput: As everyone knows, the realuminization of the primary, secondary, and tertiary have dramatically increased the throughput of the telescope. See the report by Watson and Ledlow on http://www.astro.princeton.edu/APO/970203.ps. It is planned to repeat the Watson-Ledlow throughput measurements with DIS periodically to monitor this throughput. This can be done in service mode, in twilight (it remains a matter of some discussion how often this should be done. Weekly? Monthly? It of course requires photometric conditions). We obviously want to keep mirror surfaces pristine, which will be done with use of cleaning with CO_2 snow, and a more agressive avoidance of precipitation on the mirror. It would also be good to monitor throughput of SPICAM and the guider as well, to isolate problems that might arise in these instruments. Instrument issues: DIS: the fiber optic recabling by Uomoto and Brinkmann is not yet complete; they hope to finish this soon, which should eliminate a source of AC pickup. GRIM: In good seeing, the focus is seen to be nonuniform over the chip (apo35-grim #34); it is not clear whether this is a new development, or has been true for a while. It is possible that when GRIM was first installed, it was adjusted to the out-of-collimation telescope, and it is now tilted with respect to the focal plane now that the telescope has been properly collimated. This change of focus is *not* seen with the other instrument, in particular the guider. CHAOS and the artificial guide star laser are being removed from the telescope, for repairs. The group needs more than the 2-3 nights/quarter that they are getting, and are planning to look for another, presumably smaller, telescope, on which to do their development work. The polishing contract for the new secondary is close to getting bids. Last meeting's minutes are approved. Next meeting, March 10, 12:30 PM. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 126 in the apo35-general archive. 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