TITLE:   GCN CIRCULAR
NUMBER:  38022
SUBJECT: EP241021a: OHP/T193 optical observations
DATE:    24/11/01 00:10:43 GMT
FROM:    Benjamin Schneider at MIT <bschn@mit.edu>

Benjamin Schneider (MIT), Christophe Adami (LAM/Pytheas/AMU) report on behalf of a larger collaboration:

We observed the field of EP241021a (Hu et al., GCN 37834) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. A total of 55 min of exposure (1x300s + 5x600s) were obtained in the r-band starting at 21:11:05 UT on 2024-10-31 (~10.7 days after the trigger). The optical transient and its rebrightening (Fu et al., GCNs 37840, 37842; Li et al., GCNs 37844, 37846; Ror et al., GCN 37845; Zheng et al., GCN 37849; Moskvitin & Spiridonova, GCN 37850; Pugliese et al., GCN 37852; Pérez-Fournon et al., GCN 37858; Bochenek & Perley, GCN 37869; Kumar et al., GCN 37875; Busmann et al., GCN 37877; J-Jin et al., GCN 37892; Freeburn et al., GCNs 37911, 37942, Quirola-Vasquez et al., GCN 37930; Freeburn et al., GCN 37942; Moskvitin et al. GCN 37951; Pan et al., GCN 37968; Klingler et al., GCN 37990; Carotenuto et al. GCN 38014) is clearly detected in our stacked image.

The preliminary magnitude derived for the source is

r = 22.01 +/- 0.05 mag (AB)

The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction.

We acknowledge the excellent support from Observatoire de Haute-Provence and in particular Jean Balcaen for the MISTRAL observations.