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W. T. Vestrand (LANL)
While it has been known for centuries that the optical sky is variable, monitoring the sky for optical transients with durations of less than a day is a rich area of research that remains largely unexplored. The fact that spectacular optical transients exist was clearly demonstrated by the detection of an optical flash associated with a Gamma Ray Burst at redshift z=1.6. However, the depth and breath of optical sky monitoring is so incomplete that this cosmological optical transient, which reached the astounding apparent magnitude of 9, would have been missed but for the real-time position provided by a high-energy satellite. Since there are many reasons to suspect the existence of rapid optical transients that cannot be found through sky monitoring by high-energy satellites, we need all-sky optical monitoring systems that can locate rapid transients in real time.
We discuss how with existing technology it is possible to construct robotic telescope systems for monitoring all of the optical sky that can autonomously locate celestial optical transients with timescales as short as a fraction of a minute. The data from such a monitoring system could also be used to recognize important variations of known sources. Real-time alerts from such an optical all-sky monitoring system would enable otherwise impossible observations with more powerful, narrow-field telescopes that more deeply probe the physics of the rapidly varying sources.
As an example of this new type of sky monitoring system, we discuss the RAPTOR telescope system at Los Alamos National Laboratory that is designed to identify and make follow-up observations of optical transients in real time. The system is composed of two arrays of telescopes, separated by 38 kilometers, that stereoscopically monitor a field of about 1500 square degrees for transients down to about 12th magnitude in 30 seconds. Each array also contains a sensitive, higher resolution "fovea" telescope, capable of imaging at a faster cadence and providing color information. In a manner analogous to human vision, both arrays are mounted on rapidly slewing mounts so that the ``fovea" of the array can be rapidly directed for real-time follow-up observations of any interesting transient identified by the wide-field system.
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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.