[Aavso-photometry] CCD Caracterization

[Brad Walter]

Arne, Can you do a step by step description of the process you use to
characterize a CCD? This might be a good AAVSO paper "Characterizing CCD
Cameras for APASS."


I've been testing CCD systems in preparation to bring up several survey
projects.  A U9000 has been loaned to us by Robert Ayers for the Mt. John
University Observatory 24-inch, and I'll ship that South in August for
installation.  The two U16m cameras for APASS are here and are undergoing
characterization before being shipped to New Mexico in August.  In the
process, I'm setting up a pretty complete optics and electronics workshop
here at HQ so that I can test systems in a more systematic manner.
Hopefully I'll be able to get the schematics to John Saxton's linearity
tester and make a copy for here.

Finally, I've been working with the ST-8 CCD for the Bright Star Monitor
system.  This is a Takahashi FS-60C with a field flattener, giving a 1.5x2.1
degree field of view.  The first light with this system was last night, and
I'm pretty satisfied with what I see.
The images look sharp across the field (I can easily get undersampled with
the ST-8, so will probably work out of focus most of the time), and the
saturation limit is bright enough that I can work on epsilon Aurigae and
Polaris.  With a 5-second exposure, the limiting magnitude is about 12th, so
my working range of 2nd to 9th magnitude looks perfect.  The mount is a
Celestron CGEM, and it seems to be performing pretty well, considering that
I don't have it polar aligned here at HQ.  The BSM will be used to monitor
bright variables, using the same ACP scheduler as on the Sonoita telescope.
If you have some bright projects, we can schedule them through AAVSOnet.
This system will be shipped to Tom Krajci in New Mexico very soon.  I really
appreciate the help and generosity of several people in getting this system
going, including Tom, Jim Bedient, Doug Welch and an anonymous donor.  A
full web page for BSM will be online during August with frequent updates.