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A giant radio flare of Cygnus X-3

ATel #1483; S. A.Trushkin, N. N. Nizhelskij, J. V. Sotnikova (SAO RAS)
on 18 Apr 2008; 06:50 UT
Credential Certification: Sergei Trushkin (satr@sao.ru)

Subjects: Radio, Millimeter, X-ray, Request for Observations

Referred to by ATel #: 1486

Just after beginning of new activity in hard X-rays according to the ASM Swift-BAT data (15-50 keV) we detected a powerful flare from the microquasar Cygnus X-3 with the RATAN-600 radio telescope on April 18. The measured flux densities are 1.16, 5.05, 12.2, 15.94, 16.16, 13.06 and 12.3 Jy at 1, 2.15, 4.8, 7.7, 11.2, 21.7 and 30 GHz respectively (MJD54574.16). Thus the spectra has optically thick region at frequencies lower 4.8 GHz and optically thin region at frequencies higher 7.7 GHz. Such a spectrum is often measured in the beginning of the intense relativistic plasma ejection from Cygnus X-3. 15 April the fluxes from Cygnus X-3 were weaker 10 mJy (see also ATEL#1476). We will continue RATAN observations.

Radio spectrum of Cyg X-3 18 Apr 2008