TITLE: GCN CIRCULAR NUMBER: 41293 SUBJECT: GRB 250807B: Kilonova-Catcher optical afterglow detection DATE: 25/08/08 16:35:39 GMT FROM: Damien Turpin at CEA-Saclay dturpin-astro@hotmail.com
M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), M. Pillas (ULiege), M. MaĊĦek (Institute of Physics, Prague, FZU, CZ), M. Molham (NRIAG), S. Antier (OCA/IJCLAB) on behalf of the GRANDMA/Kilonova-Catcher collaboration:
We observed the field of GRB 250807B (Klingler et al., GCN 41268) detected by Swift/BAT with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the iTelescope T72 telescope operated by M. Freeberg. Our observations started at T0+11.9hr.
In our stacked frames, subtracted from the Legacy Survey DR10 template image, we detect a faint uncatalogued optical source inside the Swift/XRT position (Klingler et al., GCN 41268; Goad et al., GCN 41272) and consistent with the Swift/UVOT (Klingler et al., GCN 41268), NTT (van Dalen et al., GCN 41278) and the VLT/X-shooter (Giudice et al., GCN41289) optical afterglow .
We report our follow-up results in the table below: +---------------+-----------+-----------+----------------+--------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+===========+===========+================+==============+ | 12.4 | 11 x 300s | Rc (Vega) | 20.37 +/- 0.25 | iT72 | +---------------+-----------+-----------+----------------+--------------+
All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). 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/).
View this GCN Circular online at https://gcn.nasa.gov/circulars/41293. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...