GCN Circular 42082
Subject
GRB 251002A: Kilonova-Catcher optical afterglow detection
Event
Date
2025-10-03T09:49:33Z (2 months ago)
From
Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>
Via
Web form
S. Leonini, 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 251002A detected by SVOM/ECLAIRs and GRM (Saccardi et al., GCN 42060) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the TEC160FL and iT72 telescopes operated by M. Freeberg and with the automated and remoted 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88) operated by S. Leonini. Our observations started at TGRB+1.2hr.
In our stacked frames, subtracted from the PanSTARRS DR2 template image, we detect the optical counterpart reported by SVOM/VT (Palmerio et al., GCN 42061), LCO-1m (Turpin et al., GCN 42062), FRAM-ORM (Jelinek et al., GCN 42063), LCO-40cm (Perez-Fournon et al., GCN 42064), SAO RAS (Moskvitin et al., GCN 42065), BOOTES-6 (Perez-Garcia et al., GCN 42066), MASTER (Lipunov et al., GCN 42067), VLT/Xshooter (Saccardi et al., GCN 42076), OHP/T193 (Mandrakas et al., GCN 42077), SYSU (Cao et al., GCN 42078), SVOM/COLIBRI (FM-GFT) (Schneider et al., GCN 42080) and AbAO (Pankov et al., GCN 42081).
We report part of our follow-up results in the table below:
+---------------+-----------+-----------+----------------------+-------------+
| Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument |
+===============+===========+===========+======================+=============+
| 2.28 | 60 x 40s | Rc (Vega) | 19.08 +/- 0.22 | Montarrenti |
| 5.10 | 18 x 180s | Rc (Vega) | 19.86 +/- 0.09 | iT72 |
| 8.54 | 20 x 180s | r (AB) | 20.42 (5 sigma U.L.) | 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. Images obtained with the Johnson-cousins 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/).