MMA configurations

[Al Wootten]

Min Yun writes:
 > 
 > It seems cycling thru configurations roughly once a year seems to be
 > a reasonable compromise, but we should also require some staggering
 > between the configurational and seasonal cycles as well.  We all have 
 > varied mm science experiences and may have different views as what
 > demands the MMA science may have in terms of configuration requirements.
 > For example, I am always working on 5 sigma detections, and I'd happy 
 > with staying in the most compact configuration most of the time.
 > Al might want to do the line ratio analysis in all cases, and he
 > might need to configure very often so he can write a paper within
 > a graduate student's life time at least.  
This is much too short a timescale for me to write a paper.  Ask Bryan.

Actually, I thought we would probably reconfigure on a similar timescale
to the VLA.  I once went through the science arguments and tried to
sort out how much of the time would be spent in each configuration
(Bob asked me to do this) and concluded that the demand would be about
equal.  Frazer disagreed but I made the presentation to some committee
here anyway.  I think the science is even distributed over the arrays.
There is a significant cost to reconfiguring, so much so that
it has been suggested in the past that a way to alleviate some of our
budget shortfalls would be to skip an 'A' configuration on the VLA
(also a relatively painless way to let users feel a pinch).  Accidents
happen, more frequently during reconfiguration, as I understand things,
and we wouldn't want too much exposure there also.  The larger configurations
offer the greatest exposure, of course.  I suspect we will
go to the 10km+ configurations less often than the others owing to
hazards.  90 days every other winter, perhaps.  Let's not send the elite
troops into the quebradas without good reason.  Perhaps we would cycle
Cn-C-Cn-300m-1km-3km-10km-3km-1km-300m-Cn-C-Cn
Jun-Sep Oct  Jan Mar Jun  Sep Nov Jan  Apr-Jul
but that makes it a long time between compact configurations also.
C-Cn----300m-1km-3km-10km-C---Cn-300m-1km-3km
Jul-Sep Oct  Jan Mar Jun  Sep Nov Jan Apr Jul
and so on may make more sense.

Al



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