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GMRT low frequency radio observation of the giant flare from Cygnus X-3

ATel #1486; Sabyasachi Pal (NCRA/TIFR), S. A. Trushkin (SAO RAS) and Ishwara Chandra (NCRA/TIFR)
on 20 Apr 2008; 22:41 UT
Credential Certification: Sabyasachi Pal (spal@ncra.tifr.res.in)

Subjects: Radio, Black Hole, Transient

In response to ATEL #1483, we have observed Cygnus X-3, which is undergoing a giant flare, using Giant Meterwave Radio Telescope (GMRT) simultaneously in 614 and 244 MHz. The observation started on UT 19.04 April 2008 and lasted for about 4.5 hours. The preliminary analysis suggests that the integrated flux density from the source in 614 and 244 MHz are 1.8 and 0.14 Jy respectively with a spectral index between 614 and 244 MHz is 2.7. This signifies that absorption is taking place in the observed low frequency region and the peak of the radio spectrum (turn-over frequency) is shifted towards lower frequency than the previous day, observed by RATAN (#1483).

We thank the staff of the GMRT who have made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research.

Further observations are planned.