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Radio observations of HETE J1900.1-2455

ATel #530; M. P. Rupen (NRAO/GSFC), A. J. Mioduszewski, V. Dhawan (NRAO)
on 21 Jun 2005; 15:18 UT
Credential Certification: Michael P. Rupen (mrupen@nrao.edu)

Subjects: Radio, X-ray, Binary, Transient, Pulsar

Referred to by ATel #: 533

Very Large Array (VLA) observations of the HETE transient and millisecond pulsar HETE J1900.1-2455 (see ATels #516, #523, #525, #526) show one radio source in an ~5.4-arcmin field-of-view centered on the nominal HETE position (ATel #516). The flux density of this source in these 8.46 GHz observations was 2.4 +/- 0.1 mJy on June 19, and 2.3 +/- 0.2 mJy on June 21. The position (J2000) is
19 00 09.77 +/- 0.01 -24 54 04.3 +/- 0.1
where the error bars reflect the signal-to-noise ratio of the images and the discrepancy between the positions measured independently on the two days. This is consistent with both the HETE (ATel #516) and the RXTE PCA (ATel #525) error circles. The source is unresolved with our 3.8 x 1.4 arcsec beam. The NRAO VLA Sky Survey (NVSS; Condon et al. 1998, AJ 115, 1693) shows a source at the same position, with a flux density of 4.1 +/- 0.6 mJy at 1.4 GHz on June 4, 1996. Given the lack of variability, this is likely an unrelated background source. There is no obvious source at this position in the 2MASS images.

Apart from the above source, there is no radio source in the VLA's field-of-view, with an rms noise level of 0.055 mJy/beam on June 19, and 0.094 mJy/beam on June 21. The extrema within the region of overlap between the HETE and RXTE PCA error circles were (-0.21, +0.21 mJy/beam) on June 19, and (-0.38, +0.35 mJy/beam) on June 21. The nominal flux density at the position of the proposed optical counterpart (ATel #526) was -0.059 +/- 0.055 mJy/beam on June 19, and -0.053 +/- 0.094 mJy/beam on June 21.

At least one further observation is planned.

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.