TITLE: GCN CIRCULAR NUMBER: 41682 SUBJECT: EP250901a: Mondy, Assy and SAO RAS optical limits DATE: 25/09/03 20:14:49 GMT FROM: Alexander Moskvitin at SAO RAS <mosk@sao.ru> A. Moskvitin (SAO RAS), A. Pozanenko (IKI), E. Klunko (ISTP), V. Kim, M. Krugov (FAI), O. Spiridonova (SAO RAS) report on behalf of GRB follow-up team and IKI-GRB-FuN: We observed the field of EP250901a (Song et al., GCNs 41627, 41651) with the 1.5m AZT-33IK telescope of the Solar Sayan Observatory (Mondy), 1.5m AZT-20 telescope of Assy Observatory and 1.0m Zeiss-1000 telescope of SAO RAS during the night of September 1. Within the refined FXT error circle (Song et al., GCN 41651) we didn't detect any new objects down to the following limits. UT_start t_mid-T0, h exp, s filter up.lim telescope FWHM 13:51:06 2.250997 30 x 120 R 23.2 Mondy, AZT-33IK 2".0 16:17:59 4.837000 61 x 60 r 22.8(AB) Assy, AZT-20 2".6 16:57:33 5.231111 14 x 120 Rc 22.4 SAO, Zeiss-1000 2".1 These preliminary results are in an agreement with the limits from MASTER (Lipunov et al., GCN 41629) and Mephisto (Liu et al., GCN 41631). In the stacked R band image of AZT-33IR within FXT error circle localization (Song et al., GCN 41651) we detected two objects, both presented in the PanSTARRS DR1 images and PS1 catalog, the 1st one is also visible in z-band image of the Legacy Survey DR10. obj. R. A. Decl. (J2000) R_mag +/- err #1 18:12:10.03 +18:42:25.0 22.5 +/- 0.2 #2 18:12:09.78 +18:42:28.3 23.2 +/- 0.3 Also in the stacked image of AZT-33IK we detected one object near the border of XRT circle (SWIFT J181210.9+184216; Evans et al., GCN 41644) with the coordinates of R. A. (J2000) = 18:12:11.02 Decl. (J2000) = +18:42:23.1 with uncertainness of +/- 0".4 in both coordinates, and brightness of R = 22.39 +/- 0.16. This object is presented in the PanSTARRS DR1 images and catalog. The field was calibrated with nearby stars from the PanSTARRS DR1 catalog and not corrected for Galactic extinction. RA DEC r err R err 273.042629860 18.705792060 18.284 0.004 18.048 0.009 273.048977320 18.703099150 17.400 0.004 17.204 0.008 273.046825830 18.696310020 19.130 0.017 18.940 0.017 View this GCN Circular online at https://gcn.nasa.gov/circulars/41682. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...