Kiso Observations of 20 Grbs in the Hete - 2 Era

— We established a GRB follow-up observation system at the Kiso observatory (Japan) in 2001. Since prior to this the east Asian area had been a blank for in GRB follow-up observational network, this observational system is very important for studying the temporal and spectral evolution of early afterglows. We have thus been able to make quick observations of early phase optical afterglows based on HETE-2 and INTEGRAL alerts. Thanks to this quick follow-up observational system, we have so far been able to use the Kiso observatory to monitor 20 events, and conduct follow-up observations in the optical and near infrared wavelengths. PACS 95.55.Cs – Ground-based ultraviolet, optical and infrared telescopes. PACS 98.70.Rz – gamma-ray source; gamma-ray bursts. 1. – Kiso Observatory The TOO system for prompt GRB follow-up observations has been in operation at the Kiso observatory since 2001 [1]. We have also established a follow-up observation system based on this system at the Lulin observatory, Taiwan [2]. The Kiso observatory is located in Nagano-Prefecture, Japan, It has a 105 cm Schmidt telescope and two other instruments, a 2k×2k CCD camera, and a near infrared camera named KONIC (Kiso Observatory Near-Infrared Camera). The 2k×2k camera's FOV. is 50 ×50 arcmin and the limited magnitudes are 22.0 mag, 22.5 mag, 21.0 mag and 21.0 mag. (for each B,V,R,I band, 10 σ, 900 sec exposure). The KONIC's FOV. is 20 arcmin and the limited magnitude are 13.0 mag, 12.3 mag and 10.8 mag (for each J,H,K band). Otherwise, we also use two objective prisms. These prisms allow low-dispersion slit less spectroscopy with a 2k × 2k CCD. The FOV is 50 ×50 arcmin.