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GCN Circular 22252

GRB 171205A: ALMA observations
2017-12-13T12:32:39Z (6 years ago)
Daniel Perley at Liverpool JMU <>
D. A. Perley (LJMU), S. Schulze (Weizmann), and A. de Ugarte Postigo
(HETH/IAA-CSIC, DARK/NBI) report on behalf of a larger collaboration:

We observed the millimeter afterglow of GRB 171205A (D'Elia et al., GCN
22177; de Ugarte Postigo, GCN 22187) using the Atacama Large
Millimeter/Submillimeter Array (ALMA).  Observations were taken using
the band 3 (92 GHz) and band 7 (340 GHz) receivers.  The band 3
observations were carried out between 2017-12-11 09:40-10:01 UT (6.10
days after trigger) and the band 7 observations were carried out between
10:02-11:04 UT (6.13 days after trigger).

In a preliminary reduction, the afterglow is strongly detected (S/N >
100) in both channels.  We estimate a flux density of 28 mJy at 92 GHz
and a flux of 16 mJy at 340 GHz, with calibration uncertainties of ~15%
and ~25%, respectively.  We expect these uncertainties to improve
significantly after a full reduction.  Further observations are planned.

We acknowledge the support of the ALMA staff in conducting these
observations rapidly, in particular Anita Richards, Andy Biggs, and
Eelco van Kampen.

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