Radio Observations of the Nuclear Transient AT 2017gbl in IRAS 23436+5257

ATel #10679; Joe Bright, Rob Fender (University of Oxford), Gemma Anderson (Curtin University), Therese Cantwell (University of Manchester)
on 30 Aug 2017; 06:11 UT
Credential Certification: Gemma Anderson (gemma.anderson@curtin.edu.au)

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We report on observations of AT 2017gbl made at 15.5 GHz with the Arcminute Microkelvin Imager Large Array (AMI-LA). AT 2017gbl was discovered (ATel #10651) in the near-infrared on MJD 57942.56 and associated with the nucleus of the galaxy IRAS 23436+5257. We initiated observations with the AMI-LA on MJD 57947.07 and observed the source a further two times, on MJD 57963.04 and MJD 57976.0. We detect an unresolved source (with clean beam major and minor axis of ~40 and ~30 arcseconds) in all three of our 4 hour observations, with flux densities of 6.0 +/- 0.3, 6.7 +/- 0.4 and 6.7 +/- 0.3 mJy respectively. IRAS 23436+5257 is detected in NVSS (234605+531359) at 1.4 GHz with a flux density of 18.5 +/- 0.7 mJy, which would correspond to the measured 15.5 GHz flux density for a spectral index of approximately -0.45. Our flux measurements all agree within a 2 sigma significance and it is likely that host emission is significantly contributing to the AMI-LA detections. Further radio monitoring is required to determine if there is long-term radio variability that could be associated with the near-infrared transient. We would like to thank the staff at the Mullard Radio Astronomy Observatory (MRAO) for scheduling these observations.