[Aavso-photometry] What to use when there are no suitablecomparison stars in the field?

[Robin Leadbeater]

Hi Terry,

>  There is one star in
> the field TYC 8794-1530-1 with a tycho V mag of 9.589 but this is
> pretty bright compared to the variables. With a 60 sec exposure it
> half fills the dynamic range of my CCD but the variables are still a
> bit dim with a S/N giving errors of ~0.1 mag. It would be better to
> double the exposure but this will make the tyco star not usable.

Assuming it is photon count rather than read noise which is limiting the S/N 
how about summing  multiple exposures to increase dynamic range? It seemed 
to work when I used to do photometry using an 8 bit camera.

Robin