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[vsolj-alert 421] new X-ray transient

new X-ray transient


Subject: [vsnet-alert 3568] (fwd) new X-ray transient

 Date: Mon, 11 Oct 1999 14:28:29 -0400 (EDT)
 From: Ron Remillard <rr@space.mit.edu>

submitted IAUC, FYI      
(sorry if you received this earlier)

Optical searches needed!

Galactic coordinates
approx +54.0  +8.6

XTE J1859+226

A. Wood and D. A. Smith, Massachusetts Institute of Technology (MIT);
F. E. Marshall and J. Swank(Goddard Space Flight Center), report, on
behalf of the RXTE All-Sky Monitor (ASM) team at MIT and Goddard Space
Flight Center, the emergence of a new X-ray transient. The source's
intensity was measured to rise slowly during a ~12 h interval to 160
+/- 15 mCrab (2-12 keV) 1999 Oct 9.658 (UT) and 250 mCrab by Oct
10.523, confirmed by a PCA observation. The rise was consistent with a
linear increase at a rate of ~6 mCrab/h. Extrapolation indicates that
the outburst began around 1999 Oct 8.55 (UT).  The ASM spectrum is
roughly Crab-like and shows no indication of evolution.  The best
localization of this source is a parallelogram with corners at (epoch
J2000.0) R.A. = 18h58m.6, Decl. = +22o40'; 18h57m.7, +22o39';
18h59m.1, 22o32'; 19h00m.0, 22o33' (90% confidence, including an
estimate of systematic errors).  Neither the ASM catalog nor SIMBAD
records any known X-ray sources in or near this error box. A series of
PCA observations are planned. Observations at other wavelengths would
be timely.

Ron Remillard for RXTE ASM team at MIT & GSFC

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