MeerKAT observations revealed a rising outburst of the recurrent black hole GX 339-4

ATel #12287; Evangelia Tremou (CEA-Saclay), Stephane Corbel (CEA-Saclay), Rob Fender (Oxford & UCT), Patrick Woudt (UCT), James Miller-Jones (Curtin), Julien Girard (CEA-Saclay) on behalf of the ThunderKAT collaboration
on 12 Dec 2018; 07:22 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Evangelia Tremou (evangelia.tremou@cea.fr)

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As part of the ThunderKAT Large Survey Programme (Fender et al.2017, arXiv:1711.04132), the recurrent black hole transient GX 339-4 is observed regularly (on a weekly basis, usually on week-end) with the new MeerKAT radio telescope. Between September 2018 - 24 November 2018 the source remained in quiescence indicating a flux density upper limit <100uJy. The last MeerKAT observations showed that GX 339-4 is starting a new outburst. We report on the fluxes of three observing epochs, 0.25h each. Observations on 2018-11-24 10:18 (60 antennas) reveal a detection of a point source at the position of GX 339-4 with flux density 439+/-7 uJy. On 2018-12-02 09:44 (62 antennas), the source shows an increase in flux density to 868+/-19 uJy and on 2018-12-08 09:18 (63 antennas) the flux density of GX 339-4 is 1631+/-12 uJy. All observations were taken at a central frequency of 1.284 GHz with a total bandwidth of 860MHz. GX 339-4 shows a recurrent outburst activity (Corbel et al. 2013, MNRAS, 428, 2500), which makes it an ideal target to study the correlation of radio and X-ray luminosities, highlighting the disk to outflows connection. Although, X-ray observations are currently not feasible due to sun constraints, radio observations will help us to cover the initial phase of the outburst. Further monitoring is ongoing. ThunderKAT will run for 5 years and aims to monitor 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 scheduling 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 Technology.