Related papers: Long-Term X-ray Variability in GX 354-0

We study the super-orbital modulation present in the Cygnus X-1 X-ray data, usually attributed to the precession of the accretion disk and relativistic jets. We find a new, strong, 326+-2 d period modulation starting in 2005, in Swift/BAT…

We report the onset of a large amplitude, statistically significant periodicity (~46 d) in the RXTE/ASM data of the prototype X-ray burster 4U 1636-53, the X-ray flux of which has been gradually declining over the last four years. This…

We investigated the optical, X-ray, and gamma-ray variability of the pulsar SAX J2103.5+4545. Our timing and spectral analyses of the X-ray and gamma-ray emissions from the source using RXTE and INTEGRAL data show that the shape of its…

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…

PG1535+547 is a bright NLS1 galaxy, whose high energy emission shows strong variability in shape and flux. ROSAT data classified it as soft X-ray weak QSO (objects whose X-ray-to-optical flux ratio is smaller than in typical QSO): their…

We present photometric observations of the field around the optical counterparts of high-mass X-ray binaries. Our aim is to study the long-term photometric variability in correlation with their X-ray activity and derive a set of secondary…

Using data from the All-Sky Monitor aboard the Rossi X-ray Timing Explorer (RXTE), we found that the 1.5-12 keV X-ray count rate of Cyg X-1 is, on time scales from 90 seconds to at least 10 days, strongly correlated with the spectral…

We present the results from the spectral analysis of more than 7,500 RXTE spectra of 10 AGN, which have been observed by RXTE regularly over a long period of time ~ 7-11 years. These observations most probably sample most of the flux and…

We present the results of a systematic search in 8.5 years of Rossi X-ray Timing Explorer All-Sky Monitor data for evidence of periodicities. The search was conducted by application of the Lomb-Scargle periodogram to the light curves of…

The galactic superluminal transient X-ray source GRS 1915+105 was observed with the pointed proportional counters (PPCs) onboard the Indian satellite IRS-P3 during 1996 July 23-27. We report here details of the behavior of this source…

We present the results of a systematic search in approximately 14 years of Rossi X-ray Timing Explorer All-Sky Monitor data for evidence of periodicities not reported by Wen et al. (2006). Two variations of the commonly used Fourier…

The Rossi X-ray Timing Explorer (RXTE) spacecraft observed the X-ray pulsar GX 1+4 for a period of 34 hours on July 19/20 1996. The source faded from an intensity of ~20 mCrab to a minimum of <~0.7 mCrab and then partially recovered towards…

Swift/BAT and RXTE/ASM observations have monitored the X-ray binary system Her X-1 for approximately 14.5 years each, and both were monitoring Her X-1 for a period of ~5.5 years. Here we study the 35-day cycle using these observations.…

We present 21 new long-term variable radio sources found commensally in two years of weekly MeerKAT monitoring of the low-mass X-ray binary GX 339-4. The new sources vary on time scales of weeks to months and have a variety of light curve…

We present the first results of the observations of the X-ray pulsars LMC X-4, 4U0352+309 and EXO1722-363 performed with the INTEGRAL observatory. The LMC X-4 was investigated during the whole superorbital cycle ($\sim$30 days) and it was…

We present the results of a study with the \emph{Swift} Burst Alert Telescope in the 14 -- 195 keV range of the long-term variability of 5 low mass X-ray binaries with reported or suspected super-orbital periods -- 4U 1636-536, 4U 1820-303,…

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 an analysis of long term X-ray monitoring observations of Circinus X-1 (Cir X-1) made with four different instruments: Vela 5B, Ariel V ASM, Ginga ASM, and RXTE ASM, over the course of more than 30 years. We use Lomb-Scargle…

A significant number of X-ray binaries are now known to exhibit long-term ``superorbital'' periodicities on timescales of $\sim$ 10 - 100 days. Several physical mechanisms have been proposed that give rise to such periodicities, in…

We report the discovery of a 2.1hr optical modulation in the transient source GS1826-24, based on two independent high time-resolution photometric observing runs. There is additional irregular variability on shorter timescales. The source…