TITLE: GCN CIRCULAR NUMBER: 43231 SUBJECT: GRB 251205A: Kilonova-Catcher optical afterglow detection DATE: 25/12/24 12:30:36 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com> M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), S. Antier (OCA/IJCLab), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), M. Pillas (IAP) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 251205A detected by Swift/BAT (Lanava et al., GCN 43005), Fermi/GBM (Fermi GBM team, GCN 43059) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the TEC160FL telescope operated by M. Freeberg. Our observations started at TGRB+10.6h and were taken with sdss r and i filters. In our stacked frames, subtracted from the Pan STARRS DR2 template image, we detect the optical counterpart reported by Swift/UVOT (Lanava et al., GCN 43005, Klingler et al., GCN 43016), MASTER (Lipunov et al., GCN 43006), GTC/OSIRIS (de Ugarte Postigo et al., GCN 43008), NOT (Malesani et al., GCN 43009), GOTO (O'Neill et al., GCN 43010), COLIBRÍ (Mandarakas et al., GCN 43011) and Zeiss-1000 Koshka observatory (Pankov et al., GCN 43012), Liverpool telescope (Bochenek et al., GCN 43015, GCN 43024, GCN 43038), GROWTH (Patil et al., GCN 43019), ZTF and ATLAS (Pérez-Fournon et al., GCN 43020), FTW (Busmann et al., GCN 43026), MITSuME (Hagio et al., GCN 43029), WINTER (Mo et al., GCN 43044), 1.3m DFOT (Gupta et al., GCN 43067). We report our follow-up results in the table below: +---------------+-----------+------------+----------------+--------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+===========+============+================+==============+ | 10.86 | 10 x 180s | sdssr (AB) | 18.35 +/- 0.09 | TEC160FL | | 12.51 | 22 x 180s | sdssi (AB) | 18.56 +/- 0.09 | TEC160FL | | 35.63 | 20 x 180s | sdssr (AB) | 19.79 +/- 0.15 | TEC160FL | | 36.72 | 19 x 180s | sdssi (AB) | 19.91 +/- 0.30 | TEC160FL | +---------------+-----------+------------+----------------+--------------+ All the data have been 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. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). 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 (http://kilonovacatcher.in2p3.fr/). View this GCN Circular online at https://gcn.nasa.gov/circulars/43231. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...