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GRB 070518: A Gamma-ray Burst with Optically Dim Luminosity (2009)

Abstract
We present our optical observations of {\em Swift} GRB 070518 afterglow obtained at the 0.8-m Tsinghua University-National Astronomical Observatory of China telescope (TNT) at Xinglong Observatory. Our follow-up observations were performed from 512 sec after the burst trigger. With the upper limit of redshift $\sim$0.7, GRB 070518 is found to be an optically dim burst. The spectra indices $\beta_{ox}$ of optical to X-ray are slightly larger than 0.5, which implies the burst might be a dark burst. The extinction $A_{V}$ of the host galaxy is 3.2 mag inferred from the X-ray hydrogen column density with Galactic extinction law, and 0.3 mag with SMC extinction law. Also, it is similar to three other low-redshift optically dim bursts, which belong to XRR or XRF, and mid-term duration($T_{90}. Comment: 8 pages, 4 figures, MNRAS accepted

Publication details
Download http://arxiv.org/abs/0911.1014
Repository arXiv (United States)
Keywords Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Type text