John,

The timing on this may be poor, but I would like to make some suggestions for future versions of CCDAP.

1. For people using CCDAP for scientific projects it would be good if collecting bias images could be interspersed through the night. Besides getting a really good bias average, these images are used for checking instrument stability. So perhaps if there were an option to take bias before/after a light frame set. Or perhaps, at preset intervals like the focus option.
2. There are times of the year when twilight is a very short time interval. Because of this (and the fact we use 5 filters) the sky flat routine sometimes does not complete. As currently done, the sky-flat routine always begins with the longer exposure settings, working its way toward the shorter. This is OK for the morning flats, but for evening flats it is more efficient to begin with the short exposures given that you are starting with a bright sky.

Take Care,
Thanks for you support.
Ron Kaitchuck

Hi Ron,

Actually timing isn't all that bad

I have some ideas to accommodate request 1 but I am curious why it is needed. If you have a temperature regulated camera, can't you make a reusable master bias for the operating temperature from many individual frames (to reduce read noise)? They can be taken on a cloudy night and reused as needed. What am I missing?

The next version will have options to significantly improve sky flat efficiency.

Yes, you can use a master bias if you believe you have a perfectly stable instrument. I have worked with $50K cameras where that is not true. We have seen bias drift and changing electrical pattern noise.

These problems are not at a level that would bother the person doing astro imaging of relatively bright objects, but for us folks trying to do milli-mag level photometry this is a big deal.

Ron Kaitchuck

Thanks for the explanation, Ron. I'll do something for version 4.