Finder OUT Motion Failure

Tuesday, March 24, 2015 2:17 PM

Problem(s) Encountered:

At the start of the night I wasn''t seeing starlight.  At first I thought the dark hatch might have been left shut, but Laura Kay and a student came down from the 2.4m to check, and it was open.  There was a racket coming from the find-guide mirror, though, and it proved to be stuck shut.  By moving back to the zenith I was able to unstick the mirror -- I guess it had an unfavorable gravity vector on it -- and I left it opened for the rest of the night.


I checked the finder travel first thing this morning.  I ran it first at zenith, IN then back OUT.  No issues at all.  I then went to the coordinates provided by John (HA+00:30:00, Dec+14) and cycled again.  Once more, no issues.  I then went to more extreme angles (HA03:30:00) and still had no problems.  A final test with the telescope to the east (HA-03:30:00) gave the slightest change of sound when moving the finder IN.  Still nothing I would be concerned about, and likely wouldn’t even typically notice if not listening for it directly.  In summary, finder appears to be working normally.

I’m wondering if the finder carriage had slightly bound on the traveling rod.  While this is pretty rare, I have seen it a couple times in the past.  If this was the case, shifting the telescope’s position might have changed the gravity vector enough to free it.  Same with cycling IN/OUT a number of times.  This shaft can be softly lubricated, but that will have to wait until the MIS is opened up.  For now, I think the system should be considered ok for use at any appropriate telescope setting.  But be mindful to see if the problem recurs.