TITLE:   GCN CIRCULAR
NUMBER:  40220
SUBJECT: EP250421a: Nickel optical upper limit
DATE:    25/04/23 23:13:36 GMT
FROM:    Weikang Zheng at UC Berkeley <weikang@berkeley.edu>

Katherine Mora, Eyouel Abate, Ansel Parke, WeiKang Zheng

and Alex Filippenko (UC Berkeley) report on behalf of the

KAIT GRB team:


We observed the field of EP250421a (Zhao et al., GCN 40198)

with the 1-m Nickel telescope located at Lick observatory,

California. Observations were performed in the R band with

600s x 6 exposures. In our coadd image, we do not detect the

optical afterglow (Lee et al., GCN. 40192; Fu et al., GCN

40193; Liu et al., GCN 40197), with an upper limit of R >

20.5 (Vega) at a mid-time of 14.9 hours after the trigger.