ASKAP-VAST detection of radio emission from GS 1354-64/BW Cir
ATel #17710; Dougal Dobie (USyd/OzGrav), Akash Anumarlapudi (UNC), Harry Qiu (SKAO), Iris de Ruiter (USyd/OzGrav) on behalf of the VAST collaboration
on 5 Mar 2026; 22:58 UT
Credential Certification: Dougal Dobie (d.dobie@sydney.edu.au)
Subjects: Radio, Binary, Black Hole, Transient
Referred to by ATel #: 17724
MAXI/GSC reported renewed X-ray activity from the black hole binary GS 1354-64 on December 25, 2025 (ATel #17563) which was followed by a slew of detections across the electromagnetic spectrum (ATel #17582, ATel #17586, ATel #17611 among others).
Here we report serendipitous radio observations of GS 1354-64 as part of the Variables And Slow Transients (VAST) project on the Australian Square Kilometre Array Pathfinder. The VAST-Galactic sub-survey carried out high-cadence monitoring of the Galactic plane between 2026-02-04 and 2026-02-09 at a central frequency of 888 MHz with each observation lasting 12 minutes.
The position of GS 1354-64 was covered seven times and we report the following preliminary flux density measurements:
| Timestamp |
Flux density (mJy) |
Uncertainty (mJy) |
| 2026-02-04T21:06:02 |
145.1 |
0.4 |
| 2026-02-04T22:19:12 |
146.8 |
0.4 |
| 2026-02-04T23:28:52 |
149.1 |
0.4 |
| 2026-02-05T18:58:42 |
131.9 |
0.4 |
| 2026-02-06T19:04:49 |
90.2 |
0.4 |
| 2026-02-07T20:11:35 |
158.9 |
0.4 |
| 2026-02-08T20:52:08 |
105.9 |
0.4 |
These measurements suggest the source has brightened substantially since the previously reported radio detection one month prior (ATel #17582)
GS 1354-64 was not detected during the first stage of VAST-Galactic, which consisted of approximately fortnightly observations carried out between November 2022-November 2023 and April 2024-December 2024. The corresponding 5-sigma upper limit on emission at the position of GS 1354-64 is typically ~1.25 mJy.
