The Bulletin of The Korean Astronomical Society (천문학회보)

The Korean Astronomical Society (한국천문학회)
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NIR Spectroscopic Observation of Ultra-Long GRB 111209A and The Early Afterglow

  • Lee, Sang-Yun (Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Dept. of Physics & Astronomy, Seoul National University) ;
  • Im, Myungshin (Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Dept. of Physics & Astronomy, Seoul National University)
  • Published : 2016.10.12
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Abstract

We observed Ultra-Long GRB 111209A using NASA's 3m InfraRed Telescope Facility (IRTF). The observation was started around 40 min later than T0 = 07:12:08 UT of Swift's BAT, lasted for 24 min. The spectrum was extracted using Spextool package. The NIR SEDs show power law distribution indicating afterglow emission from the GRB according to the fireball model with beta ~ 1.2. Also they do not show thermal emission component compared to the SED of "Christmas burst" GRB 101225A. Because there is no other NIR data with this observation epoch, this data can be compared only with TAROT-R band. It seems NIR data has the same flare which exists in R band as an optical flare.

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