TITLE: GCN CIRCULAR NUMBER: 44545 SUBJECT: GRB 260511A: UTGO H50 optical afterglow observation DATE: 26/05/11 12:13:03 GMT FROM: Harrison at University of Tasmania <hgharper9962@gmail.com> H. Harper (UTAS), K. Siellez (UTAS), B. Emptage (UTAS), K. Hill (UTAS), T. Plunkett (UTAS), A. Cole (UTAS), J.-P. Beaulieu (IAP/UTAS) report: We observed the field of the SVOM/ECLAIRs and Fermi/GBM GRB 260511A (Godet et al., GCN [44532](gcn.nasa.gov/circulars/44532); Fermi GBM Team, GCN [44529](gcn.nasa.gov/circulars/44529)) with the Harlingten 50cm (H50) at Greenhill Observatory, University of Tasmania (UTGO). Our observation started on 2026-05-11 at 08:58:59UT, ~165 minutes after Fermi trigger Observations. We obtained 11 x 120s exposure in the SDSS r’ filter. The optical counterpart (Jiang et al., GCN [44533](gcn.nasa.gov/circulars/44533); Akl et al. GCN [44534](gcn.nasa.gov/circulars/44534); Saccardi et al. GCN [44535](gcn.nasa.gov/circulars/44535); Zheng et al. GCN [44536](gcn.nasa.gov/circulars/44536); Wu et al., GCN [44538](gcn.nasa.gov/circulars/44538)) is clearly detected in our images at RA = 13:11:35.9244 (J2000) (197.8996850 deg) and Dec = -33:48:15.887 (J2000) (-33.8044130 deg) with an uncertainty of ~0.4 arcsec. Image subtraction was performed using STDpipe. We measured the following magnitude not corrected for Galactic extinction: r = 20.68 +/- 0.12 AB (mid time ~176minutes after trigger) Refined processing and more observations are still ongoing. View this GCN Circular online at https://gcn.nasa.gov/circulars/44545. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...