TITLE: GCN CIRCULAR NUMBER: 38946 SUBJECT: GRB 250114A: GRANDMA/TAROT optical afterglow detection DATE: 25/01/14 21:01:29 GMT FROM: Sarah Antier at OCA sarah.antier@oca.eu
S. Antier (OCA/ICJLAB), A. Klotz (IRAP), D. Akl (AUS), S. Karpov (FZU), M. Coughlin (UMN), C. Limonta, M. Boer, Q. Andre, A. Durroux (OCA), C. Andrade (UMN), P. Hello (IJCLAB), P-A Duverne (APC), T. Pradier (Unistra/IPHC), D. Turpin (CEA-Saclay/Irfu), N. Guessoum (AUS) on behalf of the GRANDMA collaboration:
We observed the field of GRB 250114A, detected by Swift (Klingler et al., GCN 38927) using TAROT/TCH. Observations began 1 min after T0 without filter, and we took a series of one trailed image lasting 60s and then 5x30s.
We detected the optical afterglow candidate in all images. We measured the decaying flux from 15.4 +/- 0.2 r-mag after the first minute, 16.3 +/-0.1 r-mag after the second minute, and 17.4 +/- 0.2 r-mag 5 minutes post T0.
The first 60s trailed image was analysed using techniques from Klotz et al., 2006, A&A 451, L39. The data from 2 to 5 min was reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022), using Skymapper.
The light curve and its measurements can be found at : https://skyportal-icare.ijclab.in2p3.fr/public/sources/GRB250114
Our measurements are compatible with GCNs 38927, 38929, 38930, 38933, 38934, 38943.
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/).
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