GCN Circular 38924
Subject
EP241021a: SMA radio observation
Date
2025-01-13T15:44:13Z (9 days ago)
From
Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941@gmail.com>
Via
Web form
Amar Aryan (Graduate Institute of Astronomy, National Central University, Taiwan),Giorgos Michailidis (Aristotle University of Thessaloniki, Greece), Sourya Ranjan Das (Indian Institute of Space Science and Technology, India), Bhushan Kayastha (University of Chinese Academy of Sciences, China), Garrett K. Keating (Center for Astrophysics | Harvard & Smithsonian, Cambridge, USA), and Joshua Bennett Lovell (Center for Astrophysics | Harvard & Smithsonian, Cambridge, USA) report:
We observed the field of the fast X-ray Transient EP 241021a (Hu et al. GCN 37834) with the Submillimeter Array (SMA) under program 2024B-S052 (PI: G. Keating) starting on 2024 Dec 25 at 03:13:33 UTC (64.92 days after the EP trigger) for 8.63 hours. Our observations were performed in “dual receiver mode”. We use "Uranus" as flux calibrator, "3c84" as bandpass calibrator and "0224+069" as gain calibrator.
We did not find statistically significant emission at the position of the optical counterpart discovered by Fu et al. (GCN 37840, 37842), and the corresponding radio counterpart reported by Ricci et al. (GCN 37949), Carotenuto et al. (GCN 38014) and Schroeder et al. (GCN 38640). Thus, we estimate a 3-sigma upper limit of ~ 0.8 mJy at 235 GHz.
We thank the the organizers of 2025 Submillimeter Array Interferometry School and the SMA observing staffs for scheduling and executing these observations. The Submillimeter Array is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics and is funded by the Smithsonian Institution and the Academia Sinica. We recognize that Maunakea is a culturally important site for the indigenous Hawaiian people; we are privileged to study the cosmos from its summit.