TITLE:   GCN CIRCULAR
NUMBER:  27354
SUBJECT: GRB 200306C: ALMA 3mm upper limit
DATE:    20/03/09 14:01:36 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath), S. Bhandari (CSIRO), K. D. Alexander
(Northwestern), E. Berger (Harvard), W. Fong (Northwestern), R. Margutti
(Northwestern), C. G. Mundell (University of Bath), and P. Schady
(University of Bath) report on behalf of a larger collaboration:

"We observed GRB 200306C (Gropp et al., GCN 27326) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) at 97.5 GHz over two epochs:

(i) on 2020 March 08 beginning at 05:08:54 UT (at a mean time of 0.99 d
after the burst),  and
(ii) on 2020 March 09 beginning at 05:46:00 UT (at a mean time of 2.01 d
after the burst).

No mm-band emission is detected at the optical position (Gropp et al., GCN
27326; Moskvitin, GCN 27333) in either epoch. Preliminary 3-sigma upper
limits are ~ 100 uJy and ~ 120 uJy from the individual observations and ~
80 uJy from stacking the two epochs.

We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with scheduling and executing these observations."