[vsnet-grb-info 27994] GRB 210528B: DDOTI Upper Limits on the Afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30097
SUBJECT: GRB 210528B: DDOTI Upper Limits on the Afterglow 
DATE:    21/05/29 14:32:38 GMT
FROM:    Alan M Watson at UNAM  <alan at astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Rosa L. Becerra (UNAM), Simone Dichiara
(GSFC/UMD), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl Lopez
(UNAM), Diego Gonzalez (UNAM), Margarita Pereyra (UNAM), Srihari Ravi (ASU), and
Eleonora Troja (GSFC/UMD) report:

We observed the field of the MAXI/GSC GRB 210528B (Sugawara et al., GCN Circ.,
30094) with the DDOTI wide-field imager at the Observatorio Astronómico Nacional
on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from 2021-05-29 04:07
to 06:53 UTC (from 5.3 to 8.0 hours after the trigger).

We observed a region covering aproximately 7 degrees in RA and 10 degrees in
declination (1 instrumental field or about 70 square degrees) including the
entire MAXI/GSC uncertainty region centered on 15:58:09 +05:58:58 J2000
(Sugawara et al., GCN Circ., 30094). We obtained 7860 seconds of exposure in the
w filter. We obtained AB photometry by calibration against the APASS catalog.

Within the uncertainty region, we detect no likely candidate for the afterglow
to our 5-sigma upper limits of w = 21.8.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir.