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No QPO time lags from Sco X-1 as seen with EXOSAT: a comparison with Cyg X-2
Stefan W. Dieters, Brian A. Vaughan, Erik Kuulkers +2
We have measured the phase-delay and rms amplitude spectra of CygX-2 and ScoX-1. Using EXOSAT data from the normal branch of CygX-2 we confirm earlier (Ginga) results, showing that…
Discovery of a ~1 Hz quasi-periodic oscillation in the low-mass X-ray binary 4U 1746-37
Peter G. Jonker, Michiel van der Klis, Jeroen Homan +5
We have discovered a ~1 Hz quasi-periodic oscillation (QPO) in the persistent X-ray emission and during type I X-ray bursts of the globular cluster source, dipper and low-mass X-ra…
The orbital period of the recurrent X-ray transient in Terzan 6
J. J. M. in 't Zand, A. Bazzano, M Cocchi +11
Four or five new outbursts were detected of the bright X-ray transient GRS 1747-312 in the globular cluster Terzan 6 between 1996 and 1999, through monitoring campaigns with the Wi…
LMC X-2: The First Extragalactic Z-Source?
Alan P. Smale, Erik Kuulkers
We present RXTE observations of LMC X-2 obtained during a five-day interval in 1997 December, during which the source was radiating at a mean intensity near the Eddington limit, an…
On the Magnetospheric Beat-Frequency and Lense-Thirring Interpretations of the Horizontal Branch Oscillation in the Z Sources
Dimitrios Psaltis, Rudy Wijnands, Jeroen Homan +7
We study the horizontal branch oscillations (HBO) and the two simultaneous kilohertz QPOs comparing their properties in five Z sources with the predictions of the magnetospheric be…
Multiple ejections during the 1975 outburst of A0620-00
Erik Kuulkers, R. P. Fender, Ralph E. Spencer +2
The well-known black-hole X-ray transient A0620-00 was a bright radio source during the first part of its outburst in 1975. We have revisited the available data and find for the fi…
WZ Sagittae as a DQ Herculis star
Jean-Pierre Lasota, Erik Kuulkers, Phil Charles
We argue that quiescent WZ Sge is a rapidly spinning magnetic rotator in which most of the matter transfered from the secondary is ejected from the system. Assuming that the observ…
The Optical Light Curves of Cygnus X-2 (V1341 Cyg) and the Mass of its Neutron Star
Jerome A. Orosz, Erik Kuulkers
We present U, B and V light curves (taken from the literature) of the low mass X-ray binary Cygnus X-2. The ``lower envelope'' of the light curves folded on the orbital period are…