TITLE:   GCN CIRCULAR
NUMBER:  31376
SUBJECT: GRB 211227A: Gemini South Optical Observations
DATE:    22/01/03 18:44:12 GMT
FROM:    Brendan O'Connor at UMD  <oconnorb@umd.edu>

B. O'Connor (GWU, UMD), E. Troja (NASA-GSFC), A. Gottlieb (UMD, NASA-GSFC)
report on behalf of a larger collaboration:

We observed the field of GRB 211227A (Beardmore et al., GCN #31316)
with Gemini/GMOS-S on December 30, 2021 starting at 05:36:43 UT
(corresponding to ~2.3 d post-trigger). The observations were performed
in i-band with a total exposure of 15x120 s at airmass 1.2 with good
weather conditions and seeing ~0.7".

Within the XRT enhanced position (Goad et al., GCN #31322), we do not
detect any source to depth i>26 AB mag. This is consistent with
other non-detections currently reported (Lipunov et al., GCN #31315;
Hu et al., GCN #31318; Fu et al., GCN #31320; Strausbaugh et al.,
GCN #31321; Perley, GCN #31323; Malesani et al., GCN #31324;
Belles et al., GCN #31328, Kann et al., GCN #31341).
Due to the potentially nearby distance (z=0.228; Malesani et al.,
GCN #31324), these observations disfavor a GRB-supernova similar
to SN1998bw. In terms of probing potential kilonova emission,
this limit would have detected an AT2017gfo-like event at z=0.228.

We thank the staff of the Gemini Observatory, in particular Janice
Lee and Venu Kalari, for rapid scheduling of these observations.