38 research outputs found
Gamma-ray Burst Positions from the ASM on RXTE
The RXTE/ASM has detected and positioned 14 confirmed GRB bursts (at this
writing, Jan. 1999) including six whose positions were comunicated to the
community 2 to 32 hours after the burst. Two of these latter bursts led to
measurements of optical red shifts but one, despite an easily detected x-ray
afterglow, produced no detectable optical or radio afterglow.Comment: 2 pages, 1 Figure, A&A format, accepted to appear in the proceedings
of the conference "Gamma-Ray Bursts in the Afterglow Era", Rome, 3-6 Nov,
199
X-ray Transients Monitored by the All-Sky Monitor on RXTE: A Tabulation
We present a tabulation of 46 transient x-ray sources monitored with the
All-Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE). They fall into
four broad categories: short (~d), intermediate, and long (>500 d) duration of
outbursts, and long period binary systems that flare up at periastron (e.g., Be
systems). The mixture of outburst/quiescent cycles and low-level persistent
emission in a few systems could indicate conditions are near the limit for
stable mass flow in the accretion disk. The two short-time-scale systems, CI
Cam and V4641 Sgr, are within 1 kpc of the sun, and hence many more such
systems may await discovery.Comment: 18 pages, 2 figures, Submitted for publication in "X-ray Astronomy
'99; Stellar Endpoints, AGN and the Diffuse Background", Ed: G.Malaguti,
G.Palumbo, and N.White, pub. Gordon and Breach (v.2: Additional references
added, erroneous figure replaced
X 1908+075: An X-ray Binary with a 4.4 day Period
X 1908+075 is an optically unidentified and highly absorbed X-ray source that
appears in early surveys such as Uhuru, OSO-7, Ariel V, HEAO-1, and the EXOSAT
Galactic Plane Survey. These surveys measured a source intensity in the range
of 2-12 mCrab at 2-10 keV, and the position was localized to ~ 0.5 degrees. We
use the Rossi X-ray Timing Explorer (RXTE) All Sky Monitor (ASM) to confirm our
expectation that a particular Einstein IPC detection (1E 1908.4+0730) provides
the correct position for X 1908+075. The analysis of the coded mask shadows
from the ASM for the position of 1E 1908.4+0730 yields a persistent intensity ~
8 mCrab (1.5-12 keV) over a 3 year interval beginning in 1996 February.
Furthermore, we detect a period of 4.400 +- 0.001 days with a false alarm
probability < 1.0e-7 . The folded light curve is roughly sinusoidal, with an
amplitude that is 22 % of the mean flux. The X-ray period may be attributed to
the scattering and absorption of X-rays through a stellar wind combined with
the orbital motion in a binary system. We suggest that X 1908+075 is an X-ray
binary with a high mass companion star.Comment: 6 pages, two-column,"emulateapj" style, submitted to Ap