TITLE: GCN CIRCULAR NUMBER: 37415 SUBJECT: GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate DATE: 24/09/06 16:02:02 GMT FROM: Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com> S. Belkin (HSE, IKI), V. Rumyantsev (CrAO), A. Pozanenko (IKI), and N. Pankov (HSE, IKI) report on behalf of the IKI GRB FuN: We observed the field of GRB 240905E (Dichiara et al., GCN 37397) with the ZTSh 2.6m telescope at the CrAO observatory starting on 2024-09-05 (UT) at 19:36:27. No optical source was detected in a Swift-XRT refined position (Ferro et al., GCN 37406) up to R = 24.5. However, one source which is absent in catalogues is near vicinity in XRT localization at coordinates of (J2000) 23:03:13.149 +35:31:29.74 with uncertainty of 0.5 arcsec is detected. The source is 5.5" away from the Swift-XRT Initial position centre (Dichiara et al., GCN 37397) and 11.1" away from the Swift-XRT refined position (Ferro et al., GCN 37406). The preliminary photometry of the source is as follows: Date UT Start t-T0 Filter Exp. OT err UL(3sigma) (mid, days) (s) 2024-09-05 19:36:27 0.08778 R 6720 22.03 0.05 24.5 The photometry is based on nearby USNO-B1.0 (R2) stars: RA DEC R2 23:03:16.6228872 +35:31:38.143092 15.84 23:03:10.2213480 +35:31:52.312872 17.59 23:03:23.1021888 +35:32:22.920108 15.81 23:03:10.8221064 +35:34:49.292328 16.04 View this GCN Circular online at https://gcn.nasa.gov/circulars/37415. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...