Cygnus X-2 in a radio quiet state

ATel #2052; A. Rushton (Jodrell Bank), U. Bach (MPIfR), R. Spencer (Jodrell Bank), M. Kadler (Uni. of Erlangen), M. Church (Uni. of Birmingham), M. Balucinska-Church (Uni. of Birmingham), J. Wilms (Uni. of Erlangen), M. Hanke (Uni. of Erlangen), S. Zola (Jagiellonian Uni. Cracow) and N. Schulz (MIT)
on 20 May 2009; 15:19 UT

Subjects: Binaries, Neutron Stars, Transients

The neutron star X-ray binary Cygnus X-2 was observed using the e-EVN (European VLBI Network) on May 12/13th 2009 between 23:00-13:00 UT at 5 GHz. The radio telescopes participating with the e-EVN at 5 GHz were Effelsberg, Medicina, Onsala 25m, Torun, Sheshan, Yebes, Jodrell Bank MKII, Cambridge and Knockin. A maximum data rate of 1024 Mbps were achieved from four telescopes (Effelsberg, Onsala, Torun and Jodrell Bank MKII). During the e-VLBI run simultaneous X-ray observations were made with XMM-Newton and Chandra, and optical observations with telescopes in Yunnan, the Crimea, Canakkale, Krionerion, Mt. Suhora, Cracow, La Palma, Mt. Cuba, Arizona, and Maui.

The target was not detected in a FoV centred on RA 21:44:41.2 DEC 38:19:18.0. The noise level of the image was ~30 microJy, hence the source had a five sigma upper limit of < 150 microJy/beam; the source was therefore in a "radio-quiet' state. This is consistent with certain states observed by Hjellming et al. (1989, A. A., 235, 147-155).

e-VLBI developments in Europe are supported by the EC DG-INFSO funded Communication Network Developments project 'EXPReS', Contract No. 02662. The European VLBI Network is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils.