[mmaimcal] meeting today.

[Al Wootten]

Bob asked for a review of problems and issues for each DH today.  I have
added a summary of what I said to the agenda.

Moorey pointed out that the definition of the subreflector's chop differed
between the antenna chapter (5 Hz, 2' chop) and our chapter says:


John Lugten's nutator design allows for a maximum angular acceleration of 
13200 deg/s/s, or 2000 deg/s/s on the sky, and a maximum throw of about 2 * 8.6
arcmin for symmetric beam throwing. With such a nutator, we would like possible
 beam throws ranging from 0.3 arcmin to 17.2 arcmin. Maximum nutating
frequencies of about 40 Hz could yield acceptable duty cycles for very small 
throws, and larger throws would require lower frequencies such as 5 Hz. The key
aspect of this nutator is that it must be flexible, permitting any combination 
of throws and frequencies which is physically possible. If it is affordable, 
nutators with higher peak acceleration and larger maximum throws would be 
desirable, but the stated acceleration and maximum throw are acceptable. 
The two beams should be as similar as possible to reduce the level of 
systematic errors in beam switching. 

We should think about this.

Al