Date: Tue, 11 May 1999 09:14:17 -0700
From: Russell E Owen
Subject: Re: 3.5m Night Log 990510
>The telescope pointing was fairly far off for the first object we went
>to.  I was concerned that this might be due to the tertiary, which was
>about 500 steps from its nominal position.  I commanded it to move
>again to the NA2 position, and again it came up 500 steps away from
>the commanded position, claiming that it was less than 50 steps out of
>place.  Jeff Morgan had explained that it would sense when it was in
>the slot, and differences of less than 2000 steps from the commanded
>position were acceptable.
The tertiary is clamped into place, so if moving it to the same slot
again has any affect on image position then this indicates that the
clamp is not working correctly -- a very important piece of news and
somewhat unlikely.
Moving the tertiary again may well affect the Galil's reported
position error, but that should be irrelevant unless the reported
error is very large. There's some slop in the drive system due to the
geared down motor. Not enough to adversely affect operation, but
enough to give a wide range of acceptable position error, as Jeff
said.
>Tracking and guiding were somewhat difficult when the observers
>started using horizon rotation; the new guiding software does not honk
>or beep when it loses a star, so it required vigilance.  The fact that
>the guider monitor was also not functioning made vigilance more of a
>challenge.  The new software also doesn't take subframes, so we have
>to watch more closely to figure out which star is actually being used
>-- that makes it difficult to determine when the star is about to be
>lost, as well.
Neither the TCC nor the guider Mac ever beeped when a star was lost.
Sounds like an MC or Remark function that got broken in the upgrade
(e.g. due to keyword changes). Presumably this can be fixed.
The new TCC software should take subframes exactly the same way as
the old system. Did you try setting the guiding scanning region? If
this isn't working, it's a bug.
-- Russell