TITLE: GCN CIRCULAR NUMBER: 45083 SUBJECT: GRB 260704A: NOT optical upper limits DATE: 26/07/06 06:20:45 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), A. Martin-Carrillo (UCD), A. Saccardi (CEA/Irfu), F. Mustafaj (NOT) report on behalf of a larger collaboration: We observed the field of GRB 260704A reported by SVOM/ECLAIRs (Xie et al., GCN 45072), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 9x120 s exposures in the SDSS i band at mid time 2026 Jul 5.116 UT (23.1 hr after the trigger). Our observations targeted the location of the X-ray source detected by SVOM/MXT (Xie et al., GCN 45072) and EP/FXT (Yin et al., GCN 45078). Within the EP/FXT error circle, we note the presence of a bright star (i = 15.46). Its magnitude in our image is consistent with the archival value. Its TESS light curve does not show historical variability either. This makes the star not likely related to the X-ray source. Furthermore, in the stack of our images, no new optical source is detected within the EP/FXT error region, down to the 3-sigma limiting AB magnitudes of i > 22.5 (calibrated against nearby stars from the Pan-STARRS catalog and not corrected for Galactic extinction). View this GCN Circular online at https://gcn.nasa.gov/circulars/45083. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...