TITLE:   GCN CIRCULAR
NUMBER:  28917
SUBJECT: GRB 201116A: NOT optical observations
DATE:    20/11/17 11:25:52 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>

Z.P. Zhu (NAOC, HUST), D. B. Malesani (DTU Space), D. Xu (NAOC), A. de 
Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (DARK/NBI), P. Galindo 
(NOT), report on behalf of a larger collaboration:

On 2020 Nov 17, we observed the afterglow (de Ugarte Postigo et al., GCN 
28915; Tohuvavohu  et al., GCN 28916) of GRB 201116A, detected by 
Fermi/GBM and Fermi/LAT (Axelsson et al., GCN 28907), using the Nordic 
Optical Telescope (NOT) equipped with the ALFOSC camera. We obtained one 
and three 300-s images in the r and z bands, respectively.

An optical source is detected in both filters, respectively, being 
consistent with the reported OSN position as well as with the Swift/XRT 
position. Preliminary photometry results are as follows:

     T_start          T_mid   Exptime  Filter   Mag   MagErr
      (UT)            (day)   (s)
2020-11-17T04:33:15  1.157   1x300    sdss-r   23.18 0.20
2020-11-17T04:38:51  1.165   3x300    sdss-z   22.50 0.27

calibrated against nearby PS1 stars. Our observations confirm the 
presence of the source, which is a clear afterglow candidate, though the 
photometric error and short time difference do not allow to establish 
variability compared to the OSN measurement (de Ugarte Postigo et al., 
GCN 28915).