GCN Circular 41838
Subject
EP250827b: VLA Observations
Event
Date
2025-09-16T13:27:15Z (7 days ago)
From
Genevieve Schroeder at Cornell University <genevieveschroeder@u.northwestern.edu>
Via
Web form
G. Schroeder (Cornell), D. A. Perley (LJMU), X. J. Hall (CMU), A. Y. Q. Ho (Cornell), Gokul Srinivasaragavan (UMD) report:
We observed the location of the optical transient AT2025wkm, associated with EP250827b (Schroeder et al., GCN 41635) with the NSF’s Karl G. Jansky Very Large Array under program 25B-363 (PI Perley) on 2025 September 13 at a mid time of 13:02 UT (~17.3 days post discovery) at a mid frequency of 10 GHz (4 GHz bandwidth).
Based on preliminary analysis, we detect a ~6 sigma source with a flux density of ~28 microJy. At a redshift of z = 0.120 (Sevilla et al., GCN 41639), this corresponds to a luminosity of ~1e28 erg/s/Hz. This is a factor of ~6 less luminous than the radio emission associated with SN1998bw (Kulkarni et al. Nature, 395, 663), and a factor of ~5 more luminous than the radio emission associated with SN2006aj (Soderberg et al. 2006, Nature, 442, 1014) at a similar observing frequency and epoch. If the radio emission can be attributed solely to star formation, this would indicate a radio star formation rate of ~3 Msol/year. Additional followup is planned to determine variability of the source.
We thank the VLA staff for quickly approving and executing these observations.