TITLE:   GCN CIRCULAR
NUMBER:  44020
SUBJECT: GRB 260310A / AT 2026fgk: iTelescope optical observations
DATE:    26/03/15 15:06:06 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 260310A = AT 2026fgk (Fermi GBM Team, GCN
Circ. #43951) remotely using iTelescope.Net T21 (0.43-m f/6.8
reflector + CCD + f/4.5 focal reducer) in Utah Desert Remote
Observatory at Great Basin Desert, Beryl Junction, Utah, USA.

Six images with exposures of 300 sec. and Rc filter were obtained on
2026-03-15 from 08:56:17 UT (5.166 d. after the trigger) to 09:32:41
UT (5.191 d. after the trigger). I detected the optical afterglow and
measured its magnitude (compared to Rc magnitudes of nearby stars from
the ATLAS star catalog: Tonry et al., 2018) in the stacked image =
18.0 +/- 0.1 Rc.

Magnitude is not corrected for Galactic extinction. The magnitude may
be affected by contamination from the host galaxy.

Stacked image: https://www.flickr.com/photos/filipp-romanov/55149149955/

F. D. Romanov (AAVSO).