Re: fun with coadding images on Disk Set 19

[<aah@nofs.navy.mil>]

Tom,
  Certainly doing a time series on a single field for as long
as you can, then doing the same thing on the next field, etc.
for the rest of the night is a reasonable approach.  TASS is
currently competing with the likes of ROTSE; wide field and
3-4" apertures.  There are a few other systems out there like
SuperLOTIS, ASAS, STARE, etc. all doing wide-field surveys.
So you have to look at what is unique about the Mark IV and
make the uniqueness work for you.
  In my mind (and I've told Tom this before), the unique aspects
are the simultaneous V&I exposures and better angular resolution.
Compared with ROTSE, we also can track a specific field for several
hours instead of trying to cover the entire sky, and can adjust
exposure times.
  So I suggested to Tom to sit on one field longer rather than
trying to scan an entire declination strip.  The advantage is that
you can study short time scale phenomena:  eclipsing systems,
delta Scuti stars, RR Lyrs, etc.  ROTSE may have discovered most
of the variables down to ~13th magnitude, but they don't have very
good light curves.  Don't worry about running the risk of
only measuring previously well studied objects; they are *not*
well studied.  Look at the large number of IBVS papers published
recently with light curves of ROTSE variables.  Below 13th,
the discovery field is still open, and you can do that with Tom's
scheme by coadding frames (though you lose time resolution).
  Targeted observations are another possibility.  Here you want
specific coverage of a single star; for example, a known eclipsing
binary that is going to have an eclipse during the interval it
could be observed by your site.  You then get the binary light
curve, plus you can examine the other 2999 objects in your field
for variability -- two birds with one stone.  Mike was planning
on observing the planetary transit of HD209458(?); again, a targeted
observation, with other stars that can be examined.  However, in
that particular case, STARE has already examined the field with
lots of time resolution and the chance of discovering something
new is pretty slim (unless you just want to beat Brown et al. into
press).  What Mike will gain is knowledge of how accurately he can
do photometry with his Mark IV, and then can use that knowledge in
studying other possible transit fields.
Arne