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arXiv · 1010.5035

WIDGET: System Performance and GRB Prompt Optical Observations

Yuji Urata·Makoto S. Tashiro·Toru Tamagawa·Fumihiko Usui·Makoto Kuwahara·Hungmiao Lin·Shoichi Kageyama·Wataru Iwakiri·Takako Sugasahara·Kazuki Takahara·Natsuki Kodaka·Keiichi Abe·Keisuke Masuno·Kaori Onda
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Abstract

The WIDeField telescope for Gamma-ray burst Early Timing (WIDGET) is used for a fully automated, ultra-wide-field survey aimed at detecting the prompt optical emission associated with Gamma-ray Bursts (GRBs). WIDGET surveys the HETE-2 and Swift/BAT pointing directions covering a total field of view of 62 degree x 62 degree every 10 secounds using an unfiltered system. This monitoring survey allows exploration of the optical emission before the gamma-ray trigger. The unfiltered magnitude is well converted to the SDSS r' system at a 0.1 mag level. Since 2004, WIDGET has made a total of ten simultaneous and one pre-trigger GRB observations. The efficiency of synchronized observation with HETE-2 is four times better than that of Swift. There has been no bright optical emission similar to that from GRB 080319B. The statistical analysis implies that GRB080319B is a rare event. This paper summarizes the design and operation of the WIDGET system and the simultaneous GRB observations obtained with this instrument.

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Yuji Urata, Makoto S. Tashiro, Toru Tamagawa, Fumihiko Usui, Makoto Kuwahara, Hungmiao Lin, Shoichi Kageyama, Wataru Iwakiri, Takako Sugasahara, Kazuki Takahara, Natsuki Kodaka, Keiichi Abe, Keisuke Masuno, Kaori Onda. 2010-10-25. WIDGET: System Performance and GRB Prompt Optical Observations. https://doi.org/10.1093/pasj%2F63.1.137

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