Most bright radio flare of GRS 1915+105 for last decade

ATel #13442; S. A. Trushkin, N. A. Nizhelskij, P. G. Tsybulev, N. N. Bursov, A. V. Shevchenko (SAO RAS, Russia)
on 3 Feb 2020; 06:35 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)

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In ongoing monitoring of microquasars with the RATAN-600 radio telescope we have detected very bright flare from GRS 1915+105: 375, 560, 610, 620, 870 and 880 mJy at 2.3, 4.7, 8.2, 11.2 GHz, 22.2 and 30 GHz respectively on 02 February 2020 (MJD 58881.319). These fluxes are the highest for last 10 years or even more. Only on archive data of the GBI monitoring in 1995-99 we can find the such bright radio flares at 2.3 and 8.7 GHz. The spectrum is well fitted by the power-law with spectral index +0.31. Thus the flare is optically thick: http://www.sao.ru/hq/lran/XB/1915_sp_2020f.png . In November 2019 we have reported about the bright (~400 mJy) optically thin flare (ATel #13304), that very probably were associated with the bright X-ray flare, detected by Homan et al. (ATel #13308) with X-ray telescope NICER operated on ISS. Just now we have not data about clear X-ray activity, monitoring by MAXI on ISS and Swift/BAT, but obviously such activity should be detected based on previous measurements of GRS 1915+105 and total sample of microquasars. We are conducting the multi-frequency observations daily. Observations in other spectral bands are strongly encouraged.

The RATAN multi-frequency light curves of GRS1915+105 from October 2019 to February 2020