Date: Tue, 18 May 1999 09:17:45 -0700
From: Russell E Owen
Subject: Re: 2.5m obslog 990517 ( MJD 51316 )
>   The first order of business was to get the collimation of the primary
>sorted.  Unfortunately, this was the only thing we got to.  We battled
>horrible seeing, which at times exceeded 5 arcseconds.  We ran into the
>same problem we had on Friday which was that after setting the primary to
>all zeros and relaxing, taking out coma, then backing out the proper
>collimation values, we did not get improved images.  If anything they
>looked worse, and in the same direction we were originaly trying to
>correct.
>
>   A sample set of images were taken and are in /data/spectro/guider.  A
>positive y tilt moved the image to the left, and a positive x tilt moved
>the image up ( in an saoDisplay ).
>
>      AllZeros.fits      0     0     0      0     0
>      TiltOnly.fits      0     0    18      0     0
>      NewCol.fits        0     0   -14.1 -768.6   0
>
>   After going down to the telescope and having Connie issue the primary
>move, I didn't hear the lateral links go off air.  I'm certain, I used to
>be able to hear the valve go on and off.  In fact it used to go on and off
>for every slew, and I haven't heard that in a while either.  Russell, did
>you change the TCC to stop this?  Could it have also stopped it turning off
>and on at other times as well?   French, is there something you can check
>to see if the valve is functioning properly?  Could it be stuck in one
>position?
Oy. That explains it. When I was last out at APO I modified
tdat:mir.dat to disable the lateral links. Several of us discussed
this, but I obviously didn't spread the word widely enough. For
regular operation, set the # of primary axes/actuators 4. To mess
with collimation, set the number of axes to 6. After editing
tdat:mir.dat, be sure to load the new file with the tcc command SET
BLOCK MIR/IN=TDAT:MIR
-- Russell
P.S. Robert: sorry about using the wrong email address, but I'm at
home and haven't brought my updated address book home yet.