TITLE: GCN CIRCULAR NUMBER: 42559 SUBJECT: GRB 251103A: Kilonova-Catcher optical afterglow detection DATE: 25/11/03 21:17:21 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com> R. Hellot, 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 251103A detected by SVOM (Hu et al., GCN 42534; Wang et al., GCN 42552) and Fermi/GBM (Fermi GBM team GCN 45536) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with a TEC160FL telescope operated by M. Freeberg and a CDK17 telescope located at AITP San Pedro Chile Observatory operated by R. Hellot. Our observations started at TGRB+3.2hr and were taken with sdss ri filters. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we detect the optical counterpart reported by the NOT (Schneider et al., GCN 42535), LCOGT/1m (Turpin et al., GCN 42538; Ghosh et al., GCN 42545), BOOTES-2/TELMA (Gritsevich et al., GCN 42539), GOTO (O'Neill et al., GCN 42543), SVOM/COLIBRÍ (FM-GFT) (Schneider et al., GCN 42549), Swift/UVOT (Breeveld et al., GCN 42554). We report part of our follow-up results in the table below: +---------------+-----------+--------+----------------+--------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+===========+========+================+==============+ | 3.62 | 10 x 180s | r (AB) | 18.66 +/- 0.06 | CDK17 AITP | | 4.89 | 10 x 180s | r (AB) | 19.02 +/- 0.12 | TEC160FL | | 5.46 | 10 x 180s | i (AB) | 19.33 +/- 0.28 | 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/42559. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...