TITLE:   GCN CIRCULAR
NUMBER:  21951
SUBJECT: GRB 170921A: 15 GHz upper limits from AMI
DATE:    17/10/01 20:13:58 GMT
FROM:    Kunal Mooley at Oxford U  <kunal.mooley@physics.ox.ac.uk>

K. P. Mooley (Hintze Fellow, Oxford), T. D. Staley, R. P. Fender 
(Oxford), G. E. Anderson (Curtin), T. Cantwell (Manchester), D. 
Titterington, S. H. Carey, J. Hickish, Y. C. Perrott, N. Razavi-Ghods, 
P. Scott (Cambridge), K. Grainge, A. Scaife (Manchester)

The AMI Large Array robotically triggered on the Swift alert for GRB 
170921A (D'Ai et al., GCN 21901) as part of the 4pisky program, and 
subsequent follow up observations were obtained up to 10 days 
post-burst. Our observations at 15 GHz on 2017 Sep 21.89, Sep 27.04 and 
Sep 28.97 (UT) do not reveal any radio source at the XRT location 
(Beardmore et al., GCN 21906), with 3sigma upper limits of 186 uJy, 117 
uJy and 159 uJy respectively.

We thank the AMI staff for scheduling these observations. The AMI-GRB 
database is a log of all GRB follow up observations with the AMI, and is 
available at http://4pisky.org/ami-grb/.