The 30-day monitoring of MAXI J1820+070 at 4.7 GHz

ATel #11539; S. A. Trushkin, N. A. Nizhelskij, P. G. Tsybulev, A. Erkenov (SAO RAS, Russia)
on 17 Apr 2018; 16:47 UT
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Credential Certification: Sergei Trushkin (satr@sao.ru)

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We have monitored the black hole X-ray binary MAXI J1820+070 (ASASSN-18ey) (ATel #11399) with the RATAN-600 radio telescope at 4.7, 8.2 and 11.2 GHz during period MJD 58195-58225 (ATel #11439). The most reliable daily light curve was measured at 4.7 GHz, and it showed the slow decline from 62 to 52 mJy (errors ~5%) for 30 days without strong short-term variability. The mean spectral index during last ten days is equal to +0.16 (4.7-11.2 GHz) and it can be compared with radio to mid-IR spectral index +0.33, measured Russell et al., (ATel #11533). The very slow decay of the flaring radio flux is not typical for microquasars such as GRS1915+105 or Cyg X-3, rather it reminds a persistent light curve of Cyg X-1 (ATel #10459) although MAXI J1820+070 stays yet in a flare in X-rays and optical bands. The RATAN-600 observations of the source are on-going.

The light curves at 4.7 GHz (RATAN) and at 15-50 keV (Swift/BAT) from MAXI J1820+070