TITLE: GCN CIRCULAR NUMBER: 36113 SUBJECT: GRB 240414A: Mondy optical observations DATE: 24/04/15 13:04:11 GMT FROM: Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru> N. Pankov (HSE, IKI), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB-IKI-FuN: We observed the field of GRB 240414A (Caputo et. al., GCN 36083) at redshift z=1.833 (Adami et al., GCN 36085; de Ugarte Postigo et al., GCN 36087) with 1.5-meter AZT-33IK telescope of Sayan observatory at Mondy. The observations were started on 2024-04-14 (UT) 13:56:41, i.e. ~12 hr since the Swift trigger. We took 45 frame 120 s each in the R-filter. The optical counterpart (Schneider et al., GCN 36084; Adami et al., GCN 36085; de Ugarte Postigo et al., GCN 36087; Niwano et al., GCN 36088; Lipunov et al., GCN 36095; Dutton et al., GCN 36097; Peretto, GCN 36100; Turpin et al., GCN 36101; Karambelkar et al., GCN 36103) is well detected in the stacked image at coordinates of (J2000) 12:19:08.09 +56:44:28.8. Preliminary photometry of the optical source is following: Date UT_start t-T0 Filter Exp. OT err UL(3sigma) (mid, days) (s) 2024-04-14 13:56:41 0.51395 R 44*120 20.60 0.12 22.2 The magnitudes were calibrated with respect to nearby USNO-B1.0 stars. Assuming no spectral evolution between earlier observations(Turpin et al., GCN 36101), we estimate a power law decay index to be alpha~1.2, which is in agreement with SkyNet observations (Dutton et al., GCN 36097). View this GCN Circular online at https://gcn.nasa.gov/circulars/36113. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...