TITLE: GCN CIRCULAR NUMBER: 37359 SUBJECT: GRB 240828B: GRANDMA Optical Upper Limit DATE: 24/08/31 10:49:49 GMT FROM: Dalya Akl at American Uni. SHJ <dalyaakl.d@gmail.com> D. Akl (AUS), S. Antier (OCA), M. Coughlin (UMN), P-A Duverne (APC), P. Hello (IJCLAB), C. Andrade (UMN), I. Tosta e Melo (UniCT-DFA), S. Karpov (FZU), D. Turpin (CEA-Saclay/Irfu), N. Guessoum (AUS), T. Pradier (Unistra/IPHC), R. Inasaridze, V. Aivazyan, N. Kochiashvili (AbAO), K. Noysena, M. Tanasan (NARIT), A. Kaeouch (OUCA) on behalf of the GRANDMA collaboration: We performed observations with GRANDMA and its citizen science project Kilonova-catcher (KNC) on the field of GRB 240828B, detected by SVOM/ECLAIRs (GCN 37318), with the TRT-SRO, Abastumani-T70, and KNC-ASO telescopes. The first observations started on 29-08-2024 at 10:24:08 (UTC), 0.88 days after the GRB trigger, and lasted for 0.65 days. The observations covered the B, V, R, and I filters. We did not detect any optical counterpart at the Swift-XRT afterglow position (3 arcsec, centered around RA, Dec = 63.45995, 16.71561). We also searched the SVOM/ECLAIRs localization position (25 arcmin, centered around RA, Dec = 63.36, 16.71) and did not detect any optical counterpart. Our photometry results and upper limits can be found at: https://skyportal-icare.ijclab.in2p3.fr/public/sources/S24082808/ All the data has been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Our results are consistent with Zheng et al. (GCN 37345), Moskvitin et al. (GCN 37346), Wu et al. (GCN 37347), Xin et al. (GCN 37348), Wang et al. (GCN 37350), and Schneider et al. (GCN 37352). We use the SkyPortal application (skyportal.io) to monitor our observational campaign. We thank SVOM for the useful communication. 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 49, 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/37359. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...