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Improved position of the new X-ray transient XTE J1637-498

ATEL # 1700; R. Wijnands, M. Linares, N. Degenaar (UvA), C.B. Markwardt (CRESST/U.Md./NASA/GSFC)
on 5 Sep 2008; 21:23 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Rudy Wijnands (

Subjects: X-ray, Request for Observations, Binaries, Black Holes, Neutron Stars, Transients
Referred to by ATEL #: 1704

Following the discovery of the new X-ray transient XTE J1637-498 (Atel #1699), we obtained a short (nearly 1 ksec) observation using the Swift/XRT in PC mode on 2008-09-04 at 18:15 UT. We detected one relatively bright source within the ~6 arcminutes PCA error circle at a position of RA=16:37:02.995, Dec=-49:51:37 (J2000), with an estimated uncertainty of 3.8 arcseconds radius (90% confidence).

The X-ray spectrum of the source can be adequately (a reduced chi^2 of 0.7) described by an absorbed power-law with a column density of 2.3+/-0.9E22 cmE-2 and a photon index of 1.5+/-0.4 and an absorbed 2-10 keV flux of ~2.7E-11 erg/s/cm^2. The X-ray spectrum is consistent with the source being a low-mass X-ray binary, but due to the large errors on the spectral parameters other types of system cannot be excluded (i.e., high-mass X-ray binaries). We urge follow-up observations in optical and near-IR to try to find the counterpart of the transient at these wavelengths.

We thank the Swift team for approving and scheduling our observation.

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R. E. Rutledge , Editor
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