MeerKAT and ATCA observations of the new outburst of XTE J1701-462

ATel #15617; Kelebogile Gasealahwe (UCT, SAAO), Sara E. Motta (INAF-OAB, Oxford), Jakob van den Eijnden (Oxford), Tom Russell (INAF-IASF Palermo), Rob Fender (Oxford, UCT), James Miller-Jones (Curtin), Patrick Woudt (UCT), Itumeleng Monageng (UCT, SAAO) et al. , on behalf of the ThunderKAT collaboration
on 15 Sep 2022; 08:16 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Sara Elisa Motta (sara.motta@physics.ox.ac.uk)

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The MAXI/GSC nova alert system triggered on X-ray enhancement from a position consistent with neutron star X-ray binary XTE J1701-462 (ATel #15592). A Swift observation triggered shortly after the alert confirmed that the newly detected source is indeed XTE J1701-462 which has become active after its last outburst in 2006 (ATel #15594, Homan et al. 2010, ApJ, 719, 201).

Following the reports of activity from XTE J1701-462, we performed two MeerKAT radio observations as part of the ThunderKAT Large Survey Programme (Fender et al. 2017, arXiv:1711.04132). The source was observed starting on 2022-09-07T15:35:10.4 and 2022-09-09T16:50:25.3 UTC, respectively. The observations, at a central frequency of 1.28 GHz, lasted 15 min on the source, with PKS 1934-638 as primary calibrator and J1744-5144 as the phase calibrator. Basic imaging of the data has been performed with a dedicated pipeline (OxKAT, Heywood 2020, 2020ascl.soft09003H). Preliminary imaging shows that XTE J1701-462 is not detected in either observation, with 3-sigma upper limits of 0.074 mJy/beam and 0.069 mJy/beam for the first and second epoch, respectively.

We also performed an observation with ATCA, at two simultaneous frequencies of 5.5 and 9 GHz, using PKS 1934-638 and B1646-50 as primary and phase calibrator, respectively. The observation started on 2022-09-10T05:08:05 UTC and lasted 3 hours. XTE J1701-462 is also not detected in the ATCA observation, with a 3-sigma upper limits of 54 and 42 μJy/beam at 5.5 and 9 GHz, respectively.

The radio non-detections with both telescopes are consistent with a quenched radio emission in the soft Atoll state (ATel #15605). We will continue to weekly monitor this outburst of XTE J1701-462 with MeerKAT, as well as with Swift as part of the associated X-ray follow-up observing program.

ThunderKAT will run for 5 years and targets X-ray binaries, Cataclysmic Variables, Supernovae and Gamma-Ray Bursts. As part of this programme, we perform weekly monitoring observations of all bright, active, southern hemisphere X-ray binaries in the radio band. For further information on this programme please contact Rob Fender and/or Patrick Woudt.

We thank the staff at the South African Radio Astronomy Observatory (SARAO) for their rapid scheduling of these observations. The MeerKAT telescope is operated by SARAO, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. We thank Jamie Stevens and the ATCA staff for rapidly approving and scheduling the observation.