Date: Thu, 20 May 1999 09:40:07 -0700
From: Patrick Waddell
Subject: re: 2.5 m obslog 990519 (MJD 51318)
To assess some of the impacts of M2 actuator errors I am sending out the
following scale information to convert actuator steps to linear translation.
The approx scales for M2 actuators:
7.9e-4 um/unit for ABC
8.6e-3 um/unit for D&E
The ABC actuators are 314 mm from mirror center
Thus a reported error of 10K (in Galil microsteps) is an actuator
translation error of 7.9 microns, which would tilt the secondary 25.2
microrads.
At the focal surface a tilt of this magnitude would displace images by 110
microns; the telescope boresite pointing would be different by 1.8
arcseconds.
-pat