Re: Data reduction methodology for V-I colors

["Robert J. Bradbury" <bradbury@aeiveos.com>]

On Tue, 31 Aug 2004, Doug Welch wrote:

> If the correction is a function of magnitude, then scattered
> light may be a factor. This may be scattered light in the
> flat and not in an actual image.

I'm not sure if I fully understand how frame image taking
is scheduled/managed (or whether it is the same for all
of the scopes).  I would assume that one tries to take
as many images as possible as close to vertical as possible.

[If there is a description of the scanning strategy for
one or more of the scope installations and someone could
point me at it, I'd appreciate it.]

It would seem that one might get a handle on some of the
scatter and/or background questions by taking some images
of the same region of sky at different locations (e.g.
the same stars early in the evening and late in the
evening) when you have to point the scopes in almost
opposite directions.  (This is something that normal
astronomers probably never have to deal with unless
they are going for very long exposures -- it only
comes up in "whole-sky" surveys).

Then one really wants a "best" ever image of any particular
field of view (or sub-regions of a field of view).  There
might be two or three of these, e.g. clearest night,
quietest night (greatest atmospheric stability) and
coldest night (least atmospheric background).

I'm also concerned as to what people are using as water
sources for the camera cooling and the "dry air" to
prevent condensation?  It would seem that both
of these could vary significantly over the course
of the night.

Finally, is any attempt being made to look at the same
field(s) at the same time by multiple locations?  It
looks like the scopes are spread out across the country
(in at least 2, maybe 3 time zones) and one could get
some interesting information by comparing same FOV
images from 12-2AM from the Eastern installations with
10-12PM from the Western installations.

(Sorry if any of the above demonstrates my lack of knowledge
or has been discussed previously...)

Robert