Problems in the East(?)

Thursday, November 1, 2018 11:04 AM

Problem(s) Encountered:

a) 18Oct2018:  Trouble started when I slewed to HA=-6, dec=+53.  The telescope almost got there, but stopped short a few minutes of time with an error.  I waited for a while, and started observing at HA=-5.5. But many times the tracking stopped after a couple of minutes. The telescope apparently ''prefers not'' to observe at such a position, even though it clearly can.  After a while another problem appeared: a rapid E-W oscillation, much faster than the guide camera could resolve.  This was seen many years ago, and was traced to a ~10 Hz oscillator in the system.  Eventually this problem also went away, and the telescope behaved very well at small hour angles.

  1. b)24Oct2018:  RA direction tracking had a problem while trying to observe the targets in the eastern sky. It solved after rebooting the control, but we lost 30 minutes of observation time.

c) 01Nov2018:  ...when pointing into the East at HA>3, the stars appeared elongated along the East/West direction. If the telescope was then pointed back slightly to the West even at HA>3, the stars no longer appeared elongated.


When this problem initially occurred many years ago, notch filter parameters were added to the PMAC to filter out this oscillation.  Verified that those parameters still exist (they do).  Will do further tests in the coming days to see if anything stands out.