TITLE:   GCN CIRCULAR
NUMBER:  32253
SUBJECT: GRB 220623A: NOT optical observations
DATE:    22/06/23 23:43:30 GMT
FROM:    Daniele B Malesani at Radboud U  <d.malesani@astro.ru.nl>

D. B. Malesani (Radboud Univ. and DAWN/NBI), L. Izzo (DARK/NBI), J. S. 
Thomsen (NOT), R. Clavero (IAC) report on behalf of a larger collaboration:

We observed the field of GRB 220623A (Sbarufatti et al., GCN 32243) 
using the Nordic Optical Telescope (NOT) equipped with the ALFOSC 
imager. Two sets of observations were acquired in the r and z filters, 
with mid times 2022 Jun 23.890 and 23.903 UT (14.3 and 14.6 hr after the 
trigger, respectively). The exposure times were 3x300 and 5x200 s in r 
and z, respectively.

No source is detected in our images within or close to the GRB XRT 
position (Evans et al., GCN 32248), down to the following 3-sigma limits:

r > 23.4 (AB);
z > 22.5 (AB).

Flux calibration was carried out against nearby stars from the 
Pan-STARRS catalog.