TITLE:   GCN CIRCULAR
NUMBER:  43344
SUBJECT: EP260104a: FTW optical observations
DATE:    26/01/06 15:02:43 GMT
FROM:    Malte Busmann at Ludwig-Maximilians-Universität München <m.busmann@physik.lmu.de>

Malte Busmann, Jule Augustin, Mitra Maleki (LMU), Xander J. Hall, Brendan O'Connor (CMU), Daniel Gruen (LMU), and Antonella Palmese (CMU) report:

We observed the 90% WXT localization of EP260104a (Zhou et al., GCN 43330) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r and i-band simultaneously for 10 x 180 s starting at 2026-01-06T01:09:48 UT (1.6 days after the trigger). We performed difference imaging with templates from the DESI Legacy Surveys and did not detect any uncatalogued sources to a 3-sigma upper limit of

r > 21.5 AB mag.

The non-detection is consistent with the report by Lipunov et al. (GCN 43331).

The magnitude is calibrated against the PS1 catalog and not corrected for Galactic extinction.

We thank Christoph Ries from the Wendelstein Observatory for obtaining these observations.