TITLE: GCN CIRCULAR NUMBER: 40995 SUBJECT: GRB 250706B: iTelescope optical observations DATE: 25/07/06 20:59:09 GMT FROM: Filipp Dmitrievich Romanov at Amateur astronomer <filipp.romanov.27.04.1997@gmail.com> On 2025-07-06 I observed the field of GRB 250706B (Palmerio et al., GCN Circ. 40989) remotely using the telescopes T33 (0.3-m f/9 reflector + CCD with Astrodon Series II Red filter) and T17 (0.43-m f/6.8 reflector + CMOS with Astrodon Red-E filter) of iTelescope.Net at Siding Spring Observatory, Australia. The exposure times of the photographs were 300 seconds, observations started at 19:56:23 UT (2h 50m after the trigger). I detected the optical afterglow in all images with the position (J2000.0): 02:44:55.46 -50:03:40.1. I measured the magnitudes (compared to r' magnitudes of nearby stars from the APASS DR9 catalog: Henden et al., 2016): Mid-time (UT) | Magnitude | Error | Telescope | 19:58:53.3 16.852 0.073 T33 20:04:55.9 16.790 0.046 T33 20:10:58.5 16.756 0.110 T33 20:17:00.3 16.752 0.071 T33 20:05:50.8 16.738 0.040 T17 20:11:47.9 16.875 0.054 T17 20:17:43.6 16.833 0.076 T17 Magnitudes were not corrected for Galactic extinction. F. D. Romanov (AAVSO). View this GCN Circular online at https://gcn.nasa.gov/circulars/40995. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...