AMI radio observations of the black hole candidate MAXI J1820+070
ATel #11420; Joe Bright, Rob Fender, Sara Motta (University of Oxford)
on 14 Mar 2018; 22:53 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Sara Elisa Motta (sara.motta@physics.ox.ac.uk)
Subjects: Radio, X-ray, Binary, Black Hole, Transient
Referred to by ATel #: 11423, 11426, 11427, 11432, 11437, 11439, 11440, 11451, 11458, 11510, 11533, 11540, 11574, 11576, 11578, 11609, 11723, 11820, 11827, 11831, 11833, 11887, 12061
We have observed the position of MAXI J1820+070 (ATel #11406) with the Arcminute Microkelvin Imager Large Array (AMI-LA) at 15.5 GHz. Our observation began on 14-Mar-2018/01:35:15.2 and had a total duration of 10.8 hours. J1824+1044 and 3C 286 were used as the phase and absolute flux calibrator, respectively. Date were reduced using the custom software pipeline 'reduce_dc' (e.g. Davies et al. 2009) and further flagging and then interactive cleaning were performed in CASA.
We find an unresolved source at phase center, with an integrated flux density of 15 +/- 1.5 mJy. The error reported here is a 10% calibration error, which dominates any statistical uncertainty. The measured source position is RA: 18:20:22, Dec: 07:11:10.7 and our clean beam has a major and minor FWHM of 60" and 30" respectively. This is consistent with the XRT position reported in ATel #11406. The nearest source in NVSS is around 200" away.
We plan on continued monitoring of this source and would like to thank the Mullard Radio Astronomy Observatory staff for carrying out these observations.
