Automatic CCD Imaging Systems for Time-series CCD Photometry

CCDs allow precision photometry to be done with small telescopes and at sites with less than ideal seeing conditions. The addition of an automatic observing mode makes it easy to do time-series CCD photometry of variable stars and AGN/QSOs.

At Appalachian State University's Dark Sky Observatory (DSO), we have implemented automatic imaging systems for image acquisition, scripted filter changing, data storage and quick-look online photometry two different telescopes, the 32-inch and 18-inch telescopes.

The camera at the 18-inch allows a simple system where the data acquisition PC controls a DFM Engineering filter wheel and Photometrics/Roper camera. The 32-inch system is the more complex, with three computers communicating in order to make good use of its camera's 30-second CCD-read time for filter change. Both telescopes use macros written in the PMIS software (GKR Computer Consulting). Both systems allow automatic data capture with only tended care provided by the observer. Indeed, one observer can easily run both telescopes simultaneously. The efficiency and reliability of these systems also reduces observer errors. The only unresolved problem is an occasional but rare camera-read error (the PC is apparently interrupted). We also sometimes experience a crash of the PMIS software, probably due to its 16-bit code now running in the Windows 2000 32-bit environment.

We gratefully acknowledge the support of the National Science Foundation through grants number AST-0089248 and AST-9119750, the Dunham Fund for Astrophysical Research, and the ASU Research Council.