[vsnet-grb-info 26685] GRB 201026A: NOT optical upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  28785
SUBJECT: GRB 201026A: NOT optical upper limits
DATE:    20/10/27 00:31:29 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani at space.dtu.dk>

L. Izzo (DARK/NBI), D. B. Malesani (DTU Space), T. Kuutma (NOT), report 
on behalf od a larger collaboration:

We observed the optical afterglow of GRB 201026A (Cenko et al., GCN 
28784) using the Nordic Optical Telescope (NOT) equipped with the ALFOSC 
imaging camera. A set of 2x300 s and 5x200 s images was secured in the 
SDSS r and z bands, respectively. The mid time of the observation was 
Oct 26.968 (36.2 min after the GRB). Observations were conducted at high 
airmass under moderate seeing conditions (1.4").

No new object is detected consistent with the XRT position, down to a 
limiting magnitude r= 21.5, z = 21.4 AB (3 sigma), calibrated against 
nearby stars from the Pan-STARRS catalog.

We note the presence of a faint, possibly extended object visible in the 
archival Pan-STARRS images, at a position consistent (RA = 13:06:58.71, 
Dec = +83:46:58.5) with that of the X-ray afterglow. This object could 
be the host galaxy of GRB 201026A, but we caution that the currently 
available uncertainty radius of the XRT position is still relatively 
large (3.9"), hence the association not robust.