Re: fun with coadding images on Disk Set 19

[<aah@nofs.navy.mil>]

Coadding to go deeper is a useful tool, and I recommend
it if someone wants to look for fainter variables in Tom's set.
Coadding has pros and cons, however.  Since there is drift
in the images, using shorter exposures and stacking will result
in smaller star profiles, a good thing.  For us high-altitude
sites, coadding permits cosmic ray removal.  However, it does
mean that multiple readout times are involved, meaning
less open-shutter time per night compared with single exposures.
The software effort is more time-consuming and complex.  The
data storage is more.
  The limiting factor is going to be the pixel size and blending.
I think V=16-17 is certainly possible away from the galactic plane,
but in the plane you might consider some of the fancier differential
image subtraction algorithms.  I also think you will get more return
per hour spent by looking at brighter sources rather than trying
to see how faint you can work.
Arne