TITLE:   GCN CIRCULAR
NUMBER:  20328
SUBJECT: GRB 161219B: Rapid ALMA Observations & Detection
DATE:    16/12/22 00:08:08 GMT
FROM:    Tanmoy Laskar at UC Berkeley  <tanmoylaskar@gmail.com>

T. Laskar (NRAO / UC Berkeley), K. D. Alexander (Harvard), and E. Berger
(Harvard) report on behalf of a larger collaboration:

We observed the Swift GRB 161219B (D’Ai et al. GCN 20296) at 3 mm with the
Atacama Large Millimeter/submillimeter Array (ALMA) beginning 2016 December
21.08 UT (1.30 days after the burst). At a mean frequency of 97 GHz, we
detect a radio source with a preliminary flux density of ~ 1 mJy at

RA (J2000) = 06:06:51.429 +/- 0.001
Dec (J2000) = -26:47:29.62 +/- 0.01

consistent with the position of the optical afterglow, the refined
Swift/XRT position (Beardmore et al. GCN 20297), and the radio afterglow
(Alexander et al. GCN 20313). Follow-up observations are planned.

We thank the JAO staff for rapidly executing these observations.