From: "Pete Newman"
Subject: Losing guide stars on scaleChange [was RE: 2.5m obslog 20011218 (MJD 52262)]
Date: Wed, 19 Dec 2001 11:27:58 -0700
> While centering on the stars, however, a 0.007 scaleChange moved
> the stars so far out, the guider could not bring them back
> in again. Usually, a scaleChange of this magnitude is easily
> handled so we chalk it up as a fermi luke.
Last time we lost guide stars during small scale changes was when secondary
mirror actuator A was failing.
I advise keeping an eye on the secondary MIGs and Heidenhain positions
(available from TPM, and they update more frequently) during scale changes.
You _should_ see all three axial actuators move in unison - if A is lagging,
then the engineers need to be informed.
--Pete