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Paper: Progress Report on the Search for Variability Among Cool White Dwarfs
Volume: 334, 14th European Workshop on White Dwarfs
Page: 605
Authors: Oswalt, T.D.; Rudkin, M.; Johnston, K.; Kissinger, J.; Menezes, K.
Abstract: CCD-based time series observations have been obtained for several dozen cool white dwarfs with absolute magnitude Mv > +15 and color 0.5 < VI < 1.3. Each target was observed continuously for at least a half night in an attempt to detect microvariability in the temperature regime where collisionally induced absorption due to molecular hydrogen and other molecular species is possible. The minimum time resolution achieved for individual objects is 10-180 sec, depending upon target brightness. So far, no periodic variability of amplitude larger than two percent has been confirmed, but several show evidence of variability near one percent. Such stable faint objects (V > +17) would serve as ideal flux standards for large aperture telescopes. All data was collected at the SARA Observatory 0.9m telescope at Kitt Peak in Arizona.
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