[vsnet-grb-info 27600] GRB 210323A: NOT optical afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29703
SUBJECT: GRB 210323A: NOT optical afterglow candidate
DATE:    21/03/24 06:43:12 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani at space.dtu.dk>

D. B. Malesani (DTU Space), A. de Ugarte Postigo (HETH/IAA-CSIC and 
DARK/NBI), Z. Zhu, D. Xu (NAO/CAS), D. A. Kann (HETH/IAA-CSIC), J. 
Martikainen (NOT and Univ. Helsinki) report on behalf of a larger 
collaboration:

We observed the field of the short GRB 210323A (Gropp et al., GCN 29699) 
using the Nordic Optical Telescope (NOT) equipped with the ALFOSC 
camera. Three observations of 10 min each were secured in the SDSS r 
filter, starting on 2021 Mar 24.229 UT (7.45 hr after the GRB). The 
field was observed at an airmass of ~2 and the seeing was 1.6".

No sources are detected within the currently available XRT error circle 
(3.5"; Gropp et al., GCN 29699). We note however the presence of an 
object about 2" S-E of the XRT circle, with coordinates (J2000):

RA = 21:11:47.33
DEC = +25:22:09.2

Its magnitude is r = 22.91 +- 0.09 AB, calibrated against nearby stars 
from Pan-STARRS. This object is not readily visible in the Pan-STARRS 
images, though its magnitude is close to the survey limit.

We consider this object as a viable afterglow candidate to GRB 210323A, 
but a confirmation is necessary to assess variability. Further 
observations are planned.