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VLBI detection of V407 Cyg

ATEL # 2536; Giroletti (INAF/IRA), E. Koerding, S. Corbel (Univ. Paris Diderot & CEA Saclay), K. Sokolovsky (MPIfR/ASC Lebedev), L. Fuhrmann, F. Schinzel (MPIfR), C.C. Cheung (NRC/NRL) on behalf of the Fermi-LAT collaboration
on 6 Apr 2010; 18:23 UT
Password Certification: Marcello Giroletti (

Subjects: Radio, Gamma Ray, Nova, Transients, Variables, Stars
Referred to by ATEL #: 2546

We report on EVN observations of the symbiotic star V407 Cyg, following its classical nova outburst (CBET #2199, CBET #2204) and its surprise detection in gamma-rays (ATel #2487) and radio cm and mm bands (ATel #2506, ATel #2511, ATel #2514). The radio continuum observations were carried out at 5 GHz by 9 telescopes for about 9 hours between 23h March 30 and 13h March 31, 2010 (UT). Data were directly streamed to the central processor at JIVE and correlated in real-time (eVLBI). The source J2102+4702 was used as a phase calibrator; the rms noise in our field is about 25 microJy/beam (naturally weighted beam was 8.1 x 6.6 mas at PA= 84 deg).

A faint radio source positionally coincident with V407 Cyg was detected at ~6 sigma significance level. The observed brightness distribution of the source can be represented by a circular Gaussian component, fitted in the visibility space with the following parameters: position RA = 21h02m09.8180s, Dec = +45d46'32.673" (J2000), flux density ~0.2 mJy, nominal deconvolved FWHM diameter ~3 mas. The total flux density detected in the region is about 0.4 mJy. This is significantly lower than 5.8+/-0.9 mJy measured at the same frequency two days earlier by ATA (ATel #2529) suggesting that the majority of the flux at this frequency is emitted on larger angular scales.

e-VLBI developments in Europe were supported by the EC DG-INFSO funded Communication Network Developments project 'EXPReS' ( The European VLBI Network ( is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils.

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R. E. Rutledge , Editor
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