Related papers: Superorbital Phase Evolution and a Soft-Hard X-ray…

We combine the decade long photometry of the Be/X-ray binary system A0538-66 provided by the MACHO and OGLE IV projects with high resolution SALT spectroscopy to provide detailed constraints on the orbital parameters and system properties.…

4U 1822-37 is a Low Mass X-ray Binary (LMXB) system with an Accretion Disk Corona. We have obtained 16 new mid-eclipse time measurements of this source during the last 13 years using X- ray observations made with the RXTE-PCA, RXTE-ASM,…

We have discovered an ultrasoft X-ray transient source, 2XMMi J184725.1-631724, which was detected serendipitously in two XMM-Newton observations in the direction of the center of the galaxy IC 4765-f01-1504 at a redshift of 0.0353. These…

We report the discovery of a new catacysmic variable system, RXJ051541+0104.6. The optical spectrum has a blue continuum with superposed H~I and He~I and II emission lines. The soft X-ray spectrum is well fit with a 50~eV black body. The…

The Burst Alert Telescope (BAT) on board Swift has accumulated extensive light curves for 265 sources (not including GRBs) in the energy range 14 to 200 keV. We present here a summary of searches for periodic modulation in the flux from…

Monitoring of pulse period variations in accreting binary pulsars is an important tool to study the interaction between the magnetosphere of the neutron star and the accretion disk. While the X-ray flux of the brightest X-ray pulsars have…

We report on optical and RXTE observations of a new high-latitude bursting X-ray transient, XTE J2123-058. We identified the optical counterpart, measured the 5.9573 hr orbital period and constrained the binary inclination and the source…

We have studied X-ray spectral state transitions that can be seen in the long- term monitoring light curves of bright X-ray binaries from the All-Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the Burst Alert…

We analysed the IGR J16465-4507 Burst Alert Teelescope survey data collected during the first 54 months of the Swift mission. The source is in a crowded field and it is revealed through an ad hoc imaging analysis at a significance level of…

We report on the long-term monitoring of three anomalous X-ray pulsars using the Rossi X-ray Timing Explorer (RXTE). We present a phase-coherent timing ephemeris for 4U 0142+61, and show that it has rotated with high stability over 4.4 yr,…

The black hole X-ray binary GX\,339-4 showed an X-ray outburst during 2021. The {\it AstroSat} captured this outburst when the source entered into the intermediate flux state while the count rate was declining. The source showed an…

We present the XMM-Newton observations obtained during four revolutions in Spring and Summer 2004 of CXOGC J174540.0-290031, a moderately bright transient X-ray source, located at only 2.9" from SgrA*. We report the discovery of sharp and…

We report long-term simultaneous optical and (RXTE) X-ray observations of the soft X-ray transient and low mass X-ray binary X1608-52 spanning from 1999 to 2001. In addition to the usual X-ray outburst and quiescent states, X1608-52 also…

We present X-ray and optical data of the newly discovered AM Her variable RX J1802.1+1804 = V884 Her. This X-ray source was observed in the ROSAT All-Sky-Survey in September 1990 and subsequently discovered as a highly variable and soft…

Her X-1, one of the brightest and best studied X-ray binaries, shows a cyclotron resonant scattering feature (CRSF) near 37 keV. This makes it an ideal target for detailed study with the Nuclear Spectroscopic Telescope Array (NuSTAR),…

By using available archival X-ray data, we significantly extended the list of times of X-ray minima. The new list includes 65 data points obtained by critically re-analyzing RXTE ASM data, 88 data points based on observations by MAXI, and…

Sco X-1 is the archetypal low mass X-ray binary (LMXB) and the brightest persistent extra-solar X-ray source in the sky. It was included in the K2 Campaign 2 field and was observed continuously for 71 days with 1 minute time resolution. In…

We present the results of Rossi X-ray Timing Explorer observations of GS 1354-644 during a modest outburst in 1997-1998. The source is one of a handful of black hole X-ray transients that are confirmed to be recurrent in X-rays. A 1987…

SAX J2103.5+4545 is the Be/X-ray binary with the shortest orbital period. It shows extended bright and faint X-ray states that last for a few hundred days. The main objective of this work is to investigate the relationship between the X-ray…

We present the results of timing and spectral analysis of X-ray high state observations of the high-mass X-ray pulsar SMC X-1 with Chandra, XMM-Newton, and ROSAT, taken between 1991 and 2001. The source has L_X ~ 3-5 x 10^38 ergs/s, and the…