TITLE:   GCN CIRCULAR
NUMBER:  27842
SUBJECT: GRB 200528A: NOT optical upper limits
DATE:    20/05/29 00:02:50 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>

D. B. Malesani (DTU Space), J. P. U. Fynbo (DAWN/NBI), L. Izzo 
(DARK/NBI), D. Xu (NAOC/CAS), T. Pursimo (NOT), report on behalf of a 
larger collaboration:

We observed the field of GRB 200528A (Ambrosi et al., GCN 27832) using 
the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. 
Observations were carried out under variable, thin clouds. After 
stacking the good images in each filter, no afterglow is visible in 
either band within the XRT position (Evans et al., GCN 27836). At mean 
epochs May 28.926 and 28.927 UT (11.78 and 11.80 hr after the GRB, 
respectively), we derive limiting magnitudes r > 23.5 and z > 22 AB 
(calibrated against nearby stars in the Pan-STARRS catalog).

We note that the galaxy visible in the archival surveys and noted by de 
Ugarte Postigo & Kann (GCN 27833) is about 10.6 arcsec away of the 
UVOT-enhanced XRT position (1.5" error; Evans et al., GCN 27836), and is 
thus likely unrelated to the GRB.