TITLE: GCN CIRCULAR NUMBER: 43853 SUBJECT: GRB 260226A : GROWTH-India Telescope optical observations DATE: 26/02/26 19:55:15 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s@iitb.ac.in> A.P. Saikia, V. Vijaykumar, T. Mohan, A. Devaraj, S. Patil, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: We observed the field of Fermi GRB 260226A (Fermi GBM team, GCN 43840) also detected by Fermi LAT (Depalo et al., GCN 43844, 43850), with 0.7m GROWTH-India Telescope (GIT). The observations started at 2026-02-26 14:33:34 UT, i.e 3.9 hours after the GBM trigger. We tiled the LAT localization region, observed the field at a position angle of approximately 45 degrees, and covered about 74% of the localization area. No new transients were detected within the observed region. Each exposure was taken in the r′ filter with an exposure time of 300 seconds. The photometric results are summarized below: Tile Number | Tmid - T0 (hours) | RA (deg) | Dec (deg) |Upper limit (5 sigma)(AB) | | ------------ | ------ | --------------- | ------------------------- | -------------- | | 1 | 3.95 | 42.05 | 8.033 | 19.7 | | 2 | 4.03 | 41.83 | 7.713 | 19.6 | | 3 | 4.12 | 41.83 | 7.873 | 19.9 | | 4 | 4.21 | 41.83 | 8.033 | 19.8 | | 5 | 4.30 | 41.83 | 8.193 | 19.6 | | 6 | 4.39 | 41.83 | 8.353 | 19.7 | | 7 | 4.47 | 41.94 | 7.713 | 19.6 | | 8 | 4.56 | 41.94 | 7.873 | 19.7 | | 9 | 4.65 | 41.94 | 8.033 | 19.6 | | 10 | 4.75 | 41.94 | 8.193 | 19.5 | | 11 | 4.84 | 41.94 | 8.353 | 19.6 | | 12 | 4.93 | 42.05 | 7.713 | 19.4 | | 13 | 5.02 | 42.05 | 7.873 | 19.2 | | 14 | 5.10 | 42.05 | 8.193 | 19.3 | | 15 | 5.19 | 42.05 | 8.353 | 19.2 | | 16 | 5.28 | 42.16 | 7.873 | 19.0 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. Our results are consistent with other optical non-detections (Lipunov et al., GCN 43847,43848, Konno et al., 43852) The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 8' x 11' field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/. View this GCN Circular online at https://gcn.nasa.gov/circulars/43853. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...