Radio detection of SAX J1808.4-3658 with MeerKAT

ATel #15584; Kelebogile Gasealahwe (UCT, SAAO), Jakob van den Eijnden (Oxford), Sara Motta (INAF-OAB, Oxford), Rob Fender (Oxford, UCT), Patrick Woudt (UCT), James Miller-Jones (Curtin), Itumeleng Monageng (UCT, SAAO), on behalf of the ThunderKAT collaboration
on 2 Sep 2022; 18:07 UT
Credential Certification: Jakob Van den Eijnden (a.j.vandeneijnden@uva.nl)

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SAX J1808.4-3658 is an accreting millisecond X-ray pulsar, that was reported to be in outburst on 19 August 2022 by NICER (ATel #15559) and MAXI (ATel #15563). Following the reports of this new outburst, we performed a MeerKAT radio observation as part of the ThunderKAT Large Survey Programme (Fender et al. 2017, arXiv:1711.04132).

The MeerKAT observation was performed on 27 August 2022 with MeerKAT at a central frequency of 1.28 GHz. The observation lasted 15 min, with J1939-6342 as the primary calibrator and J1830-3602 as the secondary calibrator. Basic imaging of the data has been performed with the dedicated pipeline OxKAT (Heywood 2020, 2020ascl.soft09003H). SAX J1808.4-3658 was detected at a preliminary flux density of 371 +/- 26 μJy/beam, measured using PyBDSF methods (Mohan & Rafferty 2015, 2015ascl.soft02007M). We will continue to weekly monitor this outburst of SAX J1808.4-3658 with MeerKAT, as well as with Swift as part of an associate X-ray 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.