TITLE:   GCN CIRCULAR
NUMBER:  35102
SUBJECT: GRB 231117A: SOAR/Goodman imaging of the afterglow
DATE:    23/11/18 18:06:31 GMT
FROM:    Charles Kilpatrick at Northwestern U <ckilpatrick@northwestern.edu>

C. D. Kilpatrick (Northwestern), L. Santana (CBPF), R. Salinas (ULS), C. Briceño (NOIRLab/CTIO), C. Fuentes (PUC), C. Bom, A. Santos (CBPF) report on behalf of a larger collaboration:

“We observed the putative host galaxy of GRB 231117A (Laha et al., GCN 30571, Navaneeth et al., GCN 35072, Cattaneo et al., GCN 35075, Svinkin et al., GCN 35079, Cheung et al., GCN 35081, Odeh et al., GCN 35084, D'Avanzo et al., GCN 35086, Rastinejad et al., GCN 35087, Gompertz et al., GCN 35088) with the Goodman High-Throughput Spectrograph mounted on the SOAR 4m telescope on Cerro Pachon, Chile.  We obtained 5x200s of imaging in r-band starting at 2023 Nov 18.03.

We detect a r=20.4+/-0.1 mag counterpart at the location of SDSS J220933.34+133119.5, consistent with the reported afterglow position reported by Yang et al. (GCN 35083) and subsequent detections of the putative afterglow (Rastinejad et al., GCN 35087, Gompertz & Ackley, GCN 35088, Kumar et al., GCN 35089, Andreoni et al., GCN 35099).  These data are on the AB magnitude system and not corrected for Galactic extinction, however we caution that these data are preliminary and there is uncertain contribution from the host galaxy in our aperture.  Additional SOAR follow up is planned.”