A flat radio spectrum of MAXI J1820+070
ATel #11439; S. A. Trushkin, N. A. Nizhelskij, P. G. Tsybulev, A. Erkenov (SAO RAS, Russia)
on 19 Mar 2018; 07:29 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)
Subjects: Radio, Optical, X-ray, Binary, Black Hole
Referred to by ATel #: 11440, 11451, 11458, 11478, 11481, 11510, 11533, 11539, 11540, 11609, 11723, 11833, 14492
We have observed the new X-ray transient MAXI J1820+070 (ATel #11399, #11400, #11403, #11404, #11406, #11418, #11421, #11423, #11424, #11426, #11427, #11432, #11437)
with the RATAN-600 radio telescope (SAO RAS, http://www.sao.ru ) at 4.7, 8.2 and 11.2 GHz on March 18 2018 (MJD 58195.161). We have measured the flux densities 62 +/- 4, 56 +/- 5, and 61 +/- 5 mJy at these frequencies respectively. Thus the instantaneous radio spectrum was almost flat, the spectral index is equal to -0.04. The recent radio measurement 15 mJy at 15 GHz (Bright et al., ATel #11420) were made with AMI-LA on 14 March 2018. Probably we see a radio flare from this black hole X-ray binary related with relativistic jets formation. We continue monitoring of this source in the long-term multi-frequency monitoring program of microquasars with RATAN-600.
