The following was presented to the APO 3.5 m users committee for information. While I doubt that there are any surprises for regular users, it might be instructive to see what first- time users see. Alan Uomoto June 2, 1996 =============================================================== The first JHU training run (May 1996) at APO was a success. On the mountain were Marsha Allen, Rupali Chandar, Arthur Davidsen, Andy Dring, Holland Ford, Scott Friedman, Gerard Gilmore, Tim Heckman, Richard Henry, Bill Oegerle, Alan Uomoto, Rosie Wyse, and Wei Zheng. The weather was just about perfect for the entire run, and everyone obtained scientifically useful data. The DIS was the primary instrument, with GRIM2 taking two half-nights. We exercised the DIS slit viewing camera, but did not have the opportunity to use the offset auto guider. I have summarized comments from the participants below. Alan Uomoto May 31, 1996 =================== GENERAL IMPRESSIONS OPERATIONS The management and staff at APO are excellent, as demonstrated by the on-time availability of the telescope and requested instruments. In particular, the observing specialists (Karen Gloria and Eddie Bergeron) were helpful, experienced, and effective. We were also very impressed with the quickness of the engineering team (Jon Davis in particular) in putting the telescope back together after rebuilding the altitude drive. The telescope was in pieces at 5pm, and they had it back together and re-calibrated by 10pm. TELESCOPE The telescope points and tracks well and produces decent images (we saw 1.1 to 1.5 arcsec during good conditions). The control system worked well, failing only when we tried to track through the zenith (a known limitation that will probably take us a while to get used to). INSTRUMENTS While the telescope is state-of-the-art, we were disappointed by the outdated instrumentation. The DIS is two generations old and suffers from problems that make it less effective than it could be. Lack of an imager with filters is a serious deficiency. JHU PRIORITES We are enthusiastic about the observatory and considered the ways that we could contribute (we understand that this is our observatory and we get out of it what we put into it). Many things were discussed, and these seemed like good short-term starting points. (1) We plan to build some air-spaced, reflective, long slits for DIS. (2) We talked about improving the DIS slitviewer and would consider leading an effort to do so. (3) Because the SDSS spectrographs will have a software user interface for the telescope and instrument, we thought this might be applied to the 3.5 m as part of the future software cleanup plan. ============================= UPGRADES, ENHANCEMENTS, FIXES Specific things JHU users would like to see. Some of these are long-term wishes and some are unlikely ever to be done. Others, however, seem like they might be easy. OPERATIONS A mechanism to enable routine upgrades and maintenance of the telescope, instruments, and hardware should be implemented. It should be easy, for example, to get the DIS CCD noise problem fixed. The impact on science is large and the repair cost is probably small. How do we do this? Can the director receive funds/resources for this kind of thing? Do we assign tasks to institutions? TELESCOPE Put fresh coatings on the secondary and tertiary now (even before recoating the primary), and consider using protected silver. Silver is considerably better than aluminum everywhere redward of 3800 A (but it fails blueward of 3500). GRIM2 wins and DIS doesn't care (until its blue sensitivity problem is fixed). DSC loses in the U, but without a filter box it's hard to find projects that would keep it on the telescope a large fraction of the time. Improving the telescope image quality by fixing the wind shake and secondary mirror should be done. DIS Remove the coherent noise from the CCDs. Real-time video of the slit (leaky guider type, 0.03 to 30 Hz) would improve observing efficiency and might also be used as an autoguider. A lot of time is wasted centering objects. More long slits. Tools to mark the target with a cursor and automatically to move it onto the slit would be nice. This should include the ability to rotate about a particular point in the slit viewing image. Can we install larger, better CCDs? The read noise is high for modern CCDs and the small format restricts wavelength coverage in high dispersion mode. Separate shutters for red and blue channels. There should be a method for the user to close the mirror cover and turn on the comparison lamps remotely. The blue sensitivity of the DIS needs fixing. GRIM2 Would be great if could implement the dithering macro from Remark. Would be even better if that routine worked -- it failed every time we tried to take more than 3 images at each position. Very tedious, especially since it failed randomly. Note the plethora of bad pixels in the detector; new one would be great! CONTROLS While we understand the evolution of the instrument control system (Remark on the Mac, CCDOPS for the slitviewer PC, and IRAF on the Sun) and can forgive its idiosyncrasies, it is probably time to consolidate the good features onto a single reliable platform. A hardware independent X-windows implementation would be a good place to start. GENERAL On the APO homepage, note altitude in large letters and say "bring a hat so you don't get skin cancer." Warn people to bring dressing gowns; this observatory is without private bathrooms or sinks (reference to SDSS dorms). ================================ SPECIFIC PROBLEMS WE ENCOUNTERED These are probably all known except, perhaps, for the telescope motion noted in the GRIM2 section. OPERATIONS There was confusion about who was allowed to use twilight time for calibrations. While we did not have problems this time, it was easy to imagine situations where conflicts would arise. For example, the lens program used dusk for DIS calibrations in imaging mode. We used DIS for spectroscopy for the remainder of the first half after which GRIM2 was installed. DIS spectroscopy would have to spend dark time doing calibrations (this didn't happen, but we wondered). DIS The CCDs show coherent noise. The noise has an amplitude of ~15 DN in the Tek CCD, and its phase changes with time, making it a pain to remove. Setup on the long slit takes too long. Three keyboards (and three computer operating systems) are needed, and it takes something like 10- 15 minutes to get started. We need a better selection of reflective slits (1.5, 2, and 3 arcsec, for example). Too much light is lost off the slit jaws. GRIM2 The first GRIM2 image after a slew showed the telescope to be moving (trailed images, about 5 arcsec, no wind). How long after "move complete" before the telescope stops shaking? Images went way out of focus -- not clear what happened. Moved filters in and out, no difference, then changed f/5 to f/10 and back. OK after that. APO APO APO APO APO Apache Point Observatory 3.5m APO APO APO APO APO This is message 68 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