[alma-config]Re: Early science Configs

[Al Wootten]

Hi John and Mark

This sounds like a reasonable plan to me.  Early on, we'll probably have
bursts of science--two weeks of science observations, then two or more
weeks of commissioning and verification, followed by a period of science
observations.  These science times might alternate between configuration
sets which would be combined to obtain useful images.  Proposal calls will
occur every six months or so in the paradigm we currently have, so the
science array wouldn't get augmented on shorter timescales than that, at least
for the first year or so.  

One major break point comes when 32 antennas are available.  At least then
but perhaps before we might consider beginning an n day reconfiguration
series, where n becomes 4 in the final stages in our current paradigm.
The Earliest Science configuration plan would then cover the period until
32 antennas were available, and would consist then of perhaps four sets
of configurations involving 6, 14, 23, 32 antennas.  Comments?

Al

John Conway writes:
 > 
 > Hi,
 > 
 >  Mark makes some good points, I agree a spatial dynamic range of 20
 > is hard for 6 antennas. but for a fully 1D array of 6 antennas close to
 > EW then  a baseline range of 20 could just about be achieved, but long
 > tracks  are then of course required to get good azimuthal coverage.
 > 
 > Its more in line with the pad pattern and expandability of the array to
 > full operation to have a 2D pattern of 6 antennas. For instance an outer
 > triangle of three antennas and an inner triangle,will give azimuthally good
 > uv covergae in 3-6hrs , but has a low spatial dynamic  range (like 3-5 maybe),
 > however by combining two such arrays one  could get a  useful array for
 > astronomical imaging,
 > 
 >       Jihn
 > 
 > 
 > On Wed, 14 Jan 2004, Mark Holdaway wrote:
 > 
 > >
 > > I think that these are reasonable boundary conditions (though a factor
 > > of 20 between long and short baselines for 6 antennas seems to be
 > > stretching it -- the VLA, with 27 antennas, has a ratio of 40), but
 > > I think the defining concepts for this task may be:
 > >
 > > (1) that we usually want to use multiple configurations to get good (u,v)
 > > coverage (this is ALMA, not OVRO).
 > >
 > > (2) that we want these configurations to be "expandable" in that
 > > we will be adding antennas every month or so.  I know this was not
 > > part of the current objective, but that is really the ultimate task.
 > > Initially (ie, when there are 6 antennas), we may move all or almost
 > > all between each configuration -- but at some point, more and more
 > > antennas will NOT be moved as we change configurations.
 > >
 > >    -Mark
 > >