Apache Point Observatory 3.5m User's Committee Meeting October 14, 2002 Attending: Al Harper, Bruce Gillespie, Ed Turner, Michael Strauss, Rene Walterbos, Bruce Balick, Mike Shull Absent: Alan Uomoto, Don York, John Morse, Chris Stubbs, Jon Holtzman Contents: Testing the telescope collimation Washing the primary mirror Miscellaneous hardware news User/Site Interface issues ************Testing the telescope collimation********************** As reported last month, APO has started a program of monitoring the collimation of the telescope roughly twice a week using a Shack-Hartmann test. First results are summarized on the following web page: http://galileo.apo.nmsu.edu/~mcmillan/sh2002_09.html It appears that the collimation seems steady for a while, then suddenly jumps. The collimation appears to move much more frequently in one axis than the other. More data are definitely needed to find out what is going on. There is broad support from the user's committee to continue this effort; it has the potential to greatly improve image quality. Some discussion of whether we know that it is the top end that is causing the trouble. It is a logical possibility that the problem might be somewhere else, such as with the primary mirror support or the tertiary. Needless to say, we would like to know this; this information could inform the decision whether to build a new top end. *****************Washing the primary mirror************************ As was reported recently (apo35-general #620), a freak rain shower caught the observers unawares, and rain fell on the primary mirror. It left rain spots, which should be cleaned off; see the images at: http://www.apo.nmsu.edu/Telescopes/ARCprogress/100402water/default.htm To wash the mirror requires removing it from its cell, which is a several-day operation. The current plan is to carry this out starting Monday, October 21 (which is scheduled engineering time); it would take roughly 5 nights. This may be postponed if it is too cold; one doesn't want the washing water to freeze. Holtzman has shown that this has not affected the throughput much, but it may be producing scattered light. It also will chemically degrade the aluminum over time, to the point that permanent coating damage will be likely if the spots are not removed quickly. So how did we get rained on in the first place? It's impossible to keep rain off a mirror unless you never open the telescope. There are situations where rain will fall out of a perfectly clear sky, the rain being blown horizontally many tens of miles before hitting the ground. To get a sense of the trade-off, our estimates are that closing the telescope an extra 4 nights per month (!!) on average would reduce the rate of wetting the mirror from approximately once per year to once per decade One possibility that was discussed was to use a series of radio rain detectors on the site; these could give a few minute warning. If rain is detected, the immediate thing to do is to close the mirror covers, then go to the dome to close the shutter. ********Miscellaneous: Cloud camera, Baffling, Instrument Status************** Speaking of weather, the IR cloud-monitoring camera has been upgraded to a much more sensitive system, which can make a continuous movie of cloud cover (the old system gave an image every five minutes). Jim Gunn, Doug Finkbeiner, Dave Schlegel and others are the ones who have made this happen. Check out http://hoggpt.apo.nmsu.edu/irsc/tonight/ (link off the APO home page) for the latest image, and example recent movies. Note that unlike the previous camera, white refers to clouds; a cloudless night appears black. But this system is still in a rudimentary form, and needs proper calibration. A design now exists for the telescope baffling, thanks to Jeff Morgan. There will be a design review in early November. The plan is to start fabrication next month; it will take about 1.5 months to build. Installation may straightforward (i.e., it might be done during the day); the first component may be in as early as January and February. This will be the first of two baffles that that need to be put into place. Most of the relevant instrument pundits were not available for the meeting, but briefly: Mike Carr plans to do a mechanics tune-up on DIS in mid-November. The DIS optics will be upgraded in December, to better match the new chips. The new Echelle acquisition camera/guider is in hand, and will be installed in November. *****************User/Site interface Issues************************************ We've had a number of problems lately with interfaces between observatory and users. Most of these are of the nature of astronomers not quite understanding that the observatory does not have the resources to do all the handholding that one might be used to at a national observatory. In particular, there have been a number of examples of: -People showing up late for their observing run. See apo35-general 618. People have been known to show up right at twilight, and to use precious dark sky time for flat-fields that they could have done just as well just after sunset. There is a policy in place for what to do if an observer doesn't show up at all, and if someone is late, it leaves the observing specialist in quite a bind whether to switch to backup projects, engineering projects etc. -Some novice observers are showing up on site without any person to teach them the ropes. While the mountaintop staff will provide orientation for new observers who are familiar with observing in general, but the training of novice observers without substantial experience on any telescope is the responsibility of the individual institutions (in the form, e.g., of a thesis advisor coming along on the run). (Editor's note: this policy needs to be formalized; more to follow in future postings). -Telescope time allocation forms have been filled out incorrectly/unclearly (apo35-general 611). One common occurence is that an observer requests, say, 6 half-nights. Their local TAC cuts them back to 3 half-nights. Ed Turner is then left with a dilemma when he tries to schedule these 3 half-nights, and the instructions make reference to 'three sets of two adjacent half nights, separated by four nights'. It may be appropriate to have people rewrite telescope allocation requests, after they see how much time they've actually been allocated. -Non-standard filters: There was a recent case of an observer putting in a request for a non-standard filter into a proposal, and then assuming that that was sufficient to have it available on the mountain. The APO policy for filters is given below in the appendix. At the Seattle AAS meeting in January, we will hold one or more meetings for the 3.5m community to discuss future plans for the telescope and other issues. Details will follow. Next meeting: Monday, November 11, 11:30 AM *************Appendix: Recap of Special Filter Policy*************** Loaned and Special filters policy Filters of the appropriate size may be brought/mailed to APO for use in SPIcam and DIS. Use of astronomer-furnished filters in the other instruments is discouraged. Notify APO staff (techstaff@apo.nmsu.edu) at least 2 weeks in advance if you intend to bring and use standard-size filters in SPIcam or DIS. We require that these filters be at APO at least two working days prior to their planned use. For filters with non-matching shapes or sizes, contact techstaff@apo.nmsu.edu at least one month in advance of their planned use for an evaluation of feasibility. Unless there is a compelling reason made in writing to the Director, all loaned filters at APO will be made available to other telescope users without first securing the owner's permission. A list of the loaned filters will be kept on the APO website, with the owner's name and contact information. If an astronomer wishes to use one or more of these filters, it would be advisable to contact its owner to ensure that the filter(s) will be at APO when needed. If a loaned filter is damaged or lost while at APO, the observatory will assume responsibility for its replacement. Filters will be fully insured by the owner when shipped to the site, and filters will be fully insured by APO when they are shipped back to the owner. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 625 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