A CCD Time‐Series Photometer

We describe a high-speed time-series CCD photometer for the prime focus of the 82 inch (2.1 m) telescope at McDonald Observatory and summarize the observational results we have obtained since it was placed into regular use in 2002 February. We compare this instrument with the three-channel time-series photometers we have previously used for the asteroseismological study of pulsating white dwarf stars, which used photomultiplier tubes (PMTs) as the detectors. We find the CCD instrument is about 9 times more sensitive than the PMT instruments used on the same telescope for the same exposure time. We can therefore find and measure variable white dwarf stars some 2.4 mag fainter than before, significantly increasing the number of such objects available for study.