TITLE: GCN CIRCULAR NUMBER: 39407 SUBJECT: GRB 250219A: GRANDMA/Kilonova-Catcher upper limits DATE: 25/02/21 14:08:21 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com> D. Turpin (CEA-Saclay/Irfu), D. Marchais (KNC), M. Freeberg (KNC), C. Andrade(UMN), S. Antier (OCA), M. Coughlin (UMN),S. Karpov (FZU), I. Tosta e Melo (UniCT-DFA), P. Hello (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), N. Guessoum (AUS) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 250219A (Daigne et al., GCN 39376) detected by SVOM/ECLAIRs with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the T-CAT 0.4m telescope at Crous des Gats Observatory (Cintegabelle, France) and the 0.43m CDK telescope at Alnitak Observatory (Spain) starting from TGRB + 5.8hr. In our stacked frames, we do not detect any optical afterglow at the position reported by Swift/XRT (Kennea et al., GCN 39379), SVOM/VT (Xin et al., GCN 39380) and COLIBRÍ (Magnani et al., GCN 39382). We obtain the following 5-sigma (Vega) upper limits: +---------------+-----------+--------+---------+-----------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Mag U.L.| Instrument| +===============+===========+========+=========+===========+ | 6.6 | 119 x 32s | Rc | 20.7 | T-CAT | | 6.6 | 119 x 32s | V | 21.3 | T-CAT | | 6.8 | 10 x 180s | Rc | 20.9 | 0.43m CDK | | 8.5 | 102 x 32s | Rc | 20.8 | T-CAT | | 8.5 | 102 x 32s | V | 21.4 | T-CAT | +---------------+-----------+--------+---------+-----------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained in Johnson Cousin filters were calibrated using the Gaia DR3 Synphot 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/39407. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...