TITLE:   GCN CIRCULAR
NUMBER:  37942
SUBJECT: EP241021a: continued SOAR observations confirm optical rebrightening
DATE:    24/10/29 17:04:36 GMT
FROM:    James Freeburn at Swinburne University of Technology <jamesfreeburn54@gmail.com>

J. Freeburn (Swinburne/OzGrav), I. Andreoni (UNC), Jonathan Carney (UNC)

We continued our observations (Freeburn et al., GCN 37911) of the field of EP241021a (Hu et al., GCN 37834) with the Goodman High Throughput Spectrograph mounted on the SOAR telescope in imaging mode (Prop. ID: SOAR2024B-021). We took four 300s exposures each in r and i-band and eight 300s exposures in g-band between 2024-10-28T03:58:11 and 2024-10-28T05:23:16 UTC. 

We detect the optical counterpart associated with EP241021a (Fu et al., GCN 37840; Gompertz et al., GCN 37835; Lipunov et al., GCN 37839; Fu et al., GCN 37842; Yang et al., GCN 37843; Li et al., GCN 37844; Li et al., GCN 37846; Zheng et al., GCN 37849; Moskvitin et al., GCN 37850; Pugliese et al., GCN 37852; Pérez-Fournon et al., GCN 37858; Bochenek et al., GCN 37869; Kumar et al., GCN 37875; Jin et al., GCN 37892; Moskvitin and Spiridonova, GCN 37910; Freeburn et al., GCN 37911; Quirola-Vasquez et al., GCN 37930) at high significance in g, r and i-bands.  With photometric calibration using the Pan-STARRS1 catalogue, with an r=2.5” aperture, we measure r~21.96 AB mag, with a red color g-i~0.4 mag.  Our results are consistent with Quirola-Vasquez et al., GCN 37930 in that they show an optical rebrightening.