EP-WXT trigger 01709176612: ASKAP radio detections and stellar association
ATel #17203; K. Rose (U. Sydney, CSIRO), J. Pritchard (CSIRO), Dougal Dobie (U. Sydney, OzGrav), D. Kaplan (UWM), I. de Ruiter (U. Sydney, OzGrav), T. Murphy (U. Sydney) on behalf of the VAST collaboration
on 23 May 2025; 23:47 UT
Credential Certification: Kovi Rose (kovirose@gmail.com)
EP-WXT trigger 01709176612 is an Einstein Probe/WXT transient (GCN #40523) that has been associated to WISEA J122501.45-521614.6 -- henceforth WISEA J1225 (GCN #40534). Here we report the detection of coincident radio emission from the Australian SKA Pathfinder (ASKAP) in several surveys which support the association with WISEA J1225, a radio-flaring M-dwarf (Pritchard et al. 2024).
We inspected the publicly available ASKAP observations and obtained Stokes I (S_I) flux densities of:
| Date [UTC] |
S_I [mJy/beam] |
Freq. [MHz] |
Len. [min] |
Survey |
| 2019 May 6.37: |
3.24 +/- 0.27 |
888 |
15 |
RACS-low |
| 2021 Jan 26.85: |
0.96 +/- 0.26 |
1368 |
15 |
RACS-mid |
| 2022 Nov 17.96: |
0.87 +/- 0.07 |
1368 |
480 |
WALLABY |
| 2023 Jun 25.48: |
1.08 +/- 0.24 |
888 |
12 |
ASKAP E&C |
| 2023 Oct 28.04: |
1.02 +/- 0.25 |
888 |
12 |
VAST |
| 2024 Apr 22.59: |
1.14 +/- 0.25 |
888 |
12 |
VAST |
| 2024 Aug 8.16: |
1.12 +/- 0.08 |
944 |
600 |
EMU |
| 2024 Oct 25.03 |
2.41 +/- 0.34 |
888 |
12 |
VAST |
The quoted uncertainties include the systematic flux scale uncertainty of approximately 6% and the RMS in quadrature with the fitted error. We find 6 non-detections in VAST observations between 2023 Jul -- Sep, 2024 Jun -- Aug, and 2024 Dec -- 2025 Feb; with a mean 5 sigma (RMS) limit of 1.01 mJy.
The observations used, in order, are: Rapid ASKAP Continuum Survey (RACS-low; McConnell et al. 2020, RACS-mid; Duchesne et al. 2023), Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY, Koribalski et al. 2020), ASKAP Engineering & Commissioning (Harvey-Smith et al. 2023), Variables and Slow Transients (VAST; Murphy et al. 2021), and Evolutionary Map of the Universe (EMU; Norris et al. 2021). All observations were conducted with a bandwidth of 288 MHz.
The average J2000 position for the ASKAP observations is :
| (R.A., |
Dec) = (186.2562 deg, |
-52.2709 deg) = (12h25m01.5s -52d16m15.3s) |
with uncertainties of +/-2 arcsec in both R.A. and Dec. We note that the ASKAP positions -- though not corrected for proper motion -- are all within <3.8" of EP-WXT trigger 01709176612 and within <2.7" of WISEA J1225. We consider the measurements with a signal-to-noise ratio (SNR) greater than 5 times the RMS to be significant detections.
This scientific work uses data obtained from Inyarrimanha Ilgari Bundara / the CSIRO's Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji People as the Traditional Owners and native title holders of the Observatory site. CSIRO's ASKAP radio telescope is part of the Australia Telescope National Facility (https://ror.org/05qajvd42). Operation of ASKAP is funded by the Australian Government with support from the National Collaborative Research Infrastructure Strategy. ASKAP uses the resources of the Pawsey Supercomputing Research Centre. Establishment of ASKAP, Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory and the Pawsey Supercomputing Research Centre are initiatives of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund. Archived data can be obtained through the CSIRO ASKAP Science Data Archive, CASDA (http://data.csiro.au/).
