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GCN Circular 12349

GRB 110915A: Deep Near-IR Limits from Magellan
2011-09-16T12:27:01Z (13 years ago)
Edo Berger at Harvard <>
E. Berger, R. Chornock, J. Strader (Harvard) and L. Spitler (Swinburne)

"We imaged the field of GRB 110915A (GCN 12335) with the FourStar near-IR
imager mounted on the Magellan/Baade 6.5-m telescope starting on 2011 Sep
16.155 UT (14.4 hr after the burst).  Observations were obtained in the J
and Ks filters in good seeing (0.6").  We do not detect any sources in
coincidence with the enhanced XRT position (GCN 12340) to a 3-sigma limit of
J>23.5 mag and Ks>23.0 mag (AB).  The X-ray flux on the same timescale
(extrapolated from the existing XRT light curve) is F_X ~ 4e-12 cgs,
indicating an expected near-IR brightness of J~19 mag and K~18.5 mag.  If
due to extinction, the required ~4.5 mag in J and Ks are suggestive of an
unusually large A_V."
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