This reminded me of stories of the old days with the 100" on Mt. Wilson, and 200" on Mt. Palomar. Photographic emulsions were notoriously slow back then; so much so that some exposures required several nights of continuous tracking to build up an image on the plate. Spectrums of distant galaxies were the worst offenders since an already feeble source had to have it's light spread-out over a larger area. An exposure was begun as soon as the target was high enough for good seeing, and ended when it had descended in the west to the point just before compromised seeing. The dark slide was replaced on the plate, and it was secured until the next night, when the field was re-aquired and the exposure started up again with the same piece of film. I'm sure that the Wilson and Palomar drives were made as precise as was humanly possible, but astrophotography still required hand-correction and guiding by eye. Imagine yourself having to stare at the same guide star for hour after hour, night after night! You begin to understand Milton Humason's pile of empty liquor bottles in the bushes outside Palomar... the radio was surely playing loudly in the dome those nights. And no bellyaching by modern amateurs allowed! ;o) On Tue, Apr 15, 2008 at 5:29 AM, Patrick Wiggins <paw@wirelessbeehive.com> wrote:
A guy on one of the other email lists I'm on posted a question about how long an exposure one can make without guiding.