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Radio observations of XTE J1739-302/IGR J17391-3021

ATel #184; M. P. Rupen, A. J. Mioduszewski, V. Dhawan (NRAO)
on 29 Aug 2003; 23:26 UT
Credential Certification: Michael P. Rupen (mrupen@nrao.edu)

Subjects: Radio, X-ray, Gamma Ray, Binary, Transient

Referred to by ATel #: 338

Very Large Array (VLA) observations of the transient X-ray source IGR J17391-3021 (possibly a recurrence of XTE J1739-302; ATEL #181) on August 28 UT show one radio source at 4.86 GHz within the INTEGRAL three arcminute error circle (ATEL #181), at

17 39 01.52    -30 19 34.9 (J2000)
where the position is accurate to ~0.2 arcseconds. The flux density was 0.9+/-0.2 mJy, after accounting for the primary beam (antenna) response. The detection was highly significant (9 sigma), and the error bar reflects both random and systematic errors. This source is ~2 arcminutes from the nominal INTEGRAL position (ATEL #181). Unfortunately the image from the NRAO VLA Sky Survey (NVSS; Condon et al. 1998, AJ 115, 1693), based on data taken at 1.4 GHz in 1995, is too confused to provide a useful constraint on variability. Further VLA observations are planned.

There are no plausible counterparts to XTE J1739-302 in this radio image, as all detected sources are more than two arcminutes from the Chandra position (ATEL #182), which presumably is accurate to better than a few arcseconds. The minimum and maximum observed radio surface brightnesses within two arcseconds of that position are (-0.20,0.19) mJy/beam, after correcting for primary beam attenuation.

Observational details:
The synthesized beam size was 1.2 x 0.4 arcsecond, with the major axis oriented at a position angle of 20 degrees. The rms noise level before primary beam correction was 0.08 mJy/beam, and the field was centered on the reported INTEGRAL position (ATEL #181). These observations were taken in spectral line mode to avoid bandwidth smearing (chromatic aberration) in the current, most extended VLA configuration (A configuration).

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