Mauna Loa Solar Observatory Observer's Log ----------------------------------------------------------------------------- Mon May 23 17:04:25 GMT 1994 Year: 94 Doy: 143 Observer: koon COMMENT: Mon May 23 17:04:44 GMT 1994 Thick overcast, no wind, temp ~45 F, observing unlikely today. DPMON COMMENT: Mon May 23 20:20:04 GMT 1994 Removed ND filter from tube connected to O2B mount. Moved O2B 2mm towards camera (ND thickness was ~6mm). Tried getting images manually, too cloudy to set focus. The Occulting Disk looks fairly well in focus in the N-S axis but not as good E-W, astigmatism? Will watch the images throughout a good day to see if the focused axis changes with bench rotation indicating possible astigmatism or mount tilt with O2B. If it focused axis stays fixed (eg, N-S) then maybe the occulting disk or camera is tilted or O1 is tilted or has astigmatism. If the focused axis doesn't translate E-W when changing O2B focus then the O2B probably isn't tilted. It might be a good idea to insert the diffuser then focus the telescope from the Occulting Disk to the camera using the O2B, then focus the telescope from the O1 to the Occulting Disk by looking at solar features and moving the O1? If there is astigmatism with the O1 then we can focus to favor the E-W axis to keep the active lattitude band in focus. Will try the O2B focusing plan on the first good observing day, then if this possible astigmatism is really a problem maybe we can work out a plan to fix it.