TITLE: GCN CIRCULAR NUMBER: 40780 SUBJECT: GRB 250615A/EP250615a: FTW optical and NIR observations DATE: 25/06/18 19:24:32 GMT FROM: Malte Busmann at Ludwig-Maximilians-Universität München m.busmann@physik.lmu.de
Malte Busmann (LMU), Brendan O’Connor (Carnegie Mellon U.), Daniel Gruen (LMU), and Antonella Palmese (Carnegie Mellon U.) report:
We observed the improved localization (Evans et al., GCN 40737; Goad et al., GCN 40739) of GRB 250615A/EP250615a (Dichiara et al., GCN 40736; Yang et al., GCN 40743; Burrows et al., GCN 40745; Tembhurnikar et al., GCN 40752; Frederiks et al., GCN 40753; Barthelmy et al. GCN 40765) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i and J band simultaneously for 20 x 180 s starting at 2025-06-17T21:29:37 UT (1.96 days after the trigger). We detect no new source in the 90% Swift/XRT localization (Evans et al., GCN 40737; Goad et al., GCN 40739) down to a 3-sigma depth of
r > 23.9 mag i > 23.3 mag J > 21.8 mag.
These upper limits are consistent with the previous observations by Kuin et al. (GCN 40747), Becerra et al. (GCN 40748), Magnani et al. (GCN 40749), and Calapai & Giorgio (GCN 40759).
The r and i band magnitudes are calibrated against the PS1 catalog and the J band is calibrated with the 2MASS Catalog. All magnitudes are provided in the AB system and are not corrected for the significant Galactic extinction at this location.
We thank Michael Schmidt from the Wendelstein Observatory staff for obtaining these observations.
View this GCN Circular online at https://gcn.nasa.gov/circulars/40780. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...