TITLE:   GCN CIRCULAR
NUMBER:  39101
SUBJECT: GRB 250129A: iTelescope optical observation
DATE:    25/01/30 20:15:55 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 250129A (Beardmore et al., GCN Circ.
39066) remotely using telescope T11 (0.51-m f/6.8 reflector + CCD +
f/4.5 focal reducer) of iTelescope.Net (located in Utah Desert Remote
Observatory at Great Basin Desert, Beryl Junction, Utah, USA) on
2025-01-30. Five images (exposure times of 300 seconds, BINx1) were
obtained with Rc filter. I detected the optical afterglow in all
images in the UVOT position. I measured the magnitude of it = 19.7 +/-
0.2 in the stacked image (mid time 13:11:06 UT = 32.43 h. after the
trigger) compared to r magnitudes of nearby stars from Pan-STARRS DR1
catalogue (Chambers et al., 2016).

Magnitude was not corrected for Galactic extinction.

Stacked image: https://www.flickr.com/photos/filipp-romanov/54297183051/

F. D. Romanov (AAVSO).