MDM Trouble Report for 2009 Jan 28 Telescope: 1.3m Observer(s): Tom Brink (University of Michigan) Instrument: 4K Problem(s) Encountered: Encountered a few minor issues last night, one of which cost me a good deal of time. 1. Had the same problem with the guide camera tv as last night. After sitting on the same guide star for a while (approximately one hour), the guide star and other stars in the tv display slowly become fainter and fainter. The faintest stars eventually disappear entirely, and the brightest star (which is the one I'm using to guide), becomes significantly fainter. It's counts fall on the guider monitor. To fix it I turn the camera intensity knob down to the minimum (which does nothing, to that point) and then turn the knob back up to it prior setting. This brings back all of the stars at the initial brightness on the guider tv. 2. The 1.3m seems to shake a lot when pointed towards a very mild wind. Maybe this is usual. Tonight when pointed towards a 10-15 mph wind the telescope shook in the N/S direction as much as 15 arcsec, making it impossible to get decent data in that direction. See ccd.0170.fits for an example. I experienced wind shake the previous night, when winds were 25-30 mph. That I expected. But I didn't expect such severe shaking at 10-15 mph. It is likely that the gusts were quite a bit higher than the online weather monitor indicates. 3. Now for the problem that cost me most of my time. At the very beginning of the night I noticed that my stars were egg shaped instead of circular; they were elongated along the NE/SW direction. See ccd.0126.fits for an example. I called Bob, and he thought this must be due to one of three things: wind, problem with guiding, or problem tracking. Wind was very light at the time, less than 10 mph. I pointed the telescope away from the wind, but the problem persisted. I turned off the guiding, and took some short exposures, but the problem still persisted, although it appeared ever so slightly better. I tried varying the tracking rate, but the problem still persisted. Ultimately I gave up, and continued to take data with egg shaped stars. I got the best results using an alternate tracking rate (15.0310) and no guiding. The problem seemed to slowly get better as the night went on, but it was never completely fixed until the following occurred (which may be serendipitous). Within IRAF I did an imhead command on an image, and was surprised to find that the RA, DEC, etc. were not being recorded in the image headers. This was true for all images I had taken that night, but not true for images taken the previous night. I also noticed that in the headers of these images, next to the field TCSLINK it said DOWN. I then opened up the TCS Agent Console, and scrolled back through the history, which shows that the TCSLINK had been down all night. The last time the TCSLINK was active was when I went to bed the prior morning. After that it states: TC% Error on GetTCSInfo(): TCS info request timed out (TCS running?) Apparently the link died sometime in the afternoon. Before I began observing, I followed the startup instructions which say to hit the refresh button on the TCS control panel gui. I did this, and it printed the comment: TCS server connection established... on the status line. So I assumed all TCS links were fine. Ultimately, I solved the problem (in the middle of the night) by typing tcsinit in to the TCS Agent Console window. After that I resumed tracking (at the sidereal rate) and guiding, and the stars were circular again (until the wind picked up!). I have no idea why typing tcsinit in to that window, and reestablishing the connection that way fixed my image distortion problem. Perhaps it was not that action that fixed the problem. But if it wasn't, then I have no idea what was the real cause of the image distortion. I'd like to thank Bob for patiently helping me try to solve this problem last night. Tom Brink ------------------------------ Submitted on 2009 Jan 29 [10:45:49]