LOOC UP: Locating and Observing Optical Counterparts to Unmodeled Pulses in Gravitational Waves
Abstract
We have begun a program, "Locating and Observing Optical Counterparts to Unmodeled Pulses in Gravitational Waves" (LOOC UP), to search promptly for optical counterparts to potential candidates for gravitational wave (GW) bursts. Several plausible GW sources are likely to also emit light, so the identification of a transient optical counterpart would confirm the GW signal and provide additional information about the progenitor. For example, it is expected that a merger of two neutron stars in a binary system close enough to be detectable in GWs may exhibit an optical counterpart as bright as R=13 magnitude initially, with a dimming of 1 magnitude per night. We carried out a pilot study in the summer of 2007 to develop methods and software tools for such a search. The first stage involves identifying potential GW burst candidates, or "triggers", by near real-time analysis of signals from the two Laser Interferometer Gravitational-Wave Observatory (LIGO) detector sites plus the Virgo GW detector in Europe, using very low thresholds on signal amplitude and requiring coincidence among the detectors. (At such low thresholds, typical noise fluctuations in the detectors produce a false trigger rate of one or more per hour.) Rough positions of putative sources are estimated from the GW data using the timing differences among detectors; this information is then used to select follow-up targets, giving preference to nearby galaxies and Milky Way globular clusters. A large number of nominal trigger times and targets were selected in this way for the pilot study. Using Las Campanas and MDM observatories, repeated optical observations of fields containing these targets were obtained starting a few hours after each trigger and continuing for several nights. We will present the methods we have developed for choosing targets for follow-ups and analyzing the optical image data for transients.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AAS...211.9903P