TITLE: GCN CIRCULAR NUMBER: 45007 SUBJECT: GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection DATE: 26/06/19 15:24:48 GMT FROM: marion.pillas@ligo.org A. Simon (TShNU of Kyiv), M. Mašek (FZU), N. Kochiashvili (AbAO), M. Pillas (IAP), D. Akl (NYUAD), R. Hanna (IJCLAB), P. Putsathan (KKU), Y. Rajabov (UBAI), S. Antier (IJCLAB), P. Hello (IJCLAB), M. Coughlin (UNM), S. Karpov (FZU), C. Douzet (IJCLAB), D. Rusanova (TShNU of Kyiv), V. Shynkarova (TShNU of Kyiv), A. Korosko (TShNU of Kyiv), O. Burkhonov (UBAI), S. Ehgamberdiev (UBAI), Y. Tillayev (UBAI), P. Put (NARIT), K. Noysena (NARIT), M. Tanasan (CMU/NARIT), D. Turpin (CEA-Saclay/Irfu), M. Freeberg (KNC), C. Limonta (OCA), A. Dupin (OCA), Q. André (OCA), M. Molham (NRIAG), E. Elhosseiny (NRIAG), A. Takey (NRIAG), T. Kvernadze (AbAO) on behalf of on GRANDMA collaboration: We continued our observations of the field of the Fermi Long GRB 260610B (Fermi GBM team, GCN 44901). The additional observations started on June 2026, 16 up to now. We still detect the optical afterglow using TTT-200cm, T150 at Abastumani Observatory, UBAI-AZT-22 at Madainak Observatory, AZT-8 at Lisnyky Observatory, KAO-1.88m at Kottamia Astronomical Observatory. We detect a re-brightening, which is consistent with other measurements reported in GCN 44955, GCN 44958, GCN 44959, GCN 44963, GCN 44993, 44999, 45003, 45004. A subset of the photometry corrected for Galactic extinction is reported in the public ACME service Skyportal/ICARE https://skyportal-icare.ijclab.in2p3.fr/source/2026owq. To access, one simply needs to create an account using your ORCID id. The data were reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the Sloan filters were calibrated using the PanSTARRS DR1 catalog. Images obtained with the Johnson-Cousins filters were calibrated using the Gaia DR3 Synphot catalog. The observations are performed under the P7 campaign of GRANDMA to monitor SVOM alerts and LSST alerts from explosive fast transients filtered by BOOM/Babamul and FINK. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (kilonovacatcher.in2p3.fr). Astrophysics Center for Multimessenger studies in Europe is supported Skyportal/ICARE (contact camille.douzet@ijclab.in2p3.fr, skyportal.io). The TTT Observing Time Rights (DTO) used were provided by Light Bridges, SL. View this GCN Circular online at https://gcn.nasa.gov/circulars/45007. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...