Related papers: GX 9+9: Variability of the X-Ray Orbital Modulatio…
The bright, strongly variable BL Lac object PKS 2155-304 was observed by XMM for two essentially uninterrupted periods of ~11 and 16 hr on 30-31 May 2000. The strongest variations occurred in the highest energy bands. After scaling for this…
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 present XMM-Newton and Chandra observations of 1E1048.1-5937, being the first to show evidence for a significant variation in the X-ray luminosity of this Anomalous X-ray Pulsar (AXP). While during the first XMM-Newton (2000 December)…
We report on 10 years of monitoring of the 8.7-s Anomalous X-ray Pulsar 4U 0142+61 using the Rossi X-Ray Timing Explorer (RXTE). This pulsar exhibited stable rotation from 2000 March until 2006 February: the RMS phase residual for a…
The source 4U 2206+54 is one of the most enigmatic high-mass X-ray binaries. In spite of intensive searches, X-ray pulsations have not been detected in the time range 0.001-1000 s. A cyclotron line at ~30 keV has been suggested by various…
We report the first detection of X-ray polarization with the Imaging X-ray Polarimetry Explorer from the X-ray pulsar (XRP) 4U 1954$+$319. The source belongs to an extremely rare class of systems in which a slowly rotating neutron star…
The intense galactic X-ray source GX 349+2 (Sco X-2) belongs to the class of persistently bright low-mass X-ray binaries called Z-sources. GX 349+2, although observed in X-rays for more than 30 years, has only recently been optically…
Optical spectroscopic observations of GX 339-4 were carried out between 1998 May (X-ray high state) and 1999 May (X-ray low state) over 7 epochs. The equivalent width of Halpha increased during the high state then decreased during the low…
Daily observations of the binary X-ray pulsar GX 1+4 were made with the Rossi X-ray Timing Explorer (RXTE) satellite between 1997 May 16-20 as part of a four-month monitoring program. On May 17 the sharp dips normally observed in the…
We report the first time-resolved photometric and spectroscopic optical observations of the X-ray source RX J2133.7+5107, identified in the ROSAT survey. A clear persistent optical light pulsation is discovered with fast photometry at a…
We present results obtained from X-ray observations of the anomalous X-ray pulsar (AXP) 4U 0142+61 taken between 2000-2007 using XMM-Newton, Chandra and Swift. In observations taken before 2006, the pulse profile is observed to become more…
After three years of no unusual activity, Anomalous X-ray Pulsar 1E 1048.1-5937 reactivated in 2007 March. We report on the detection of a large glitch (Delta(nu)/nu =1.63(2)X~10^{-5}) on 2007 March 26 (MJD 54185.9), contemporaneous with…
We report results from the first simultaneous X-ray (RXTE) and optical (SAAO) observations of the low-mass X-ray binary GS 1826-24 in June 1998. A type-I burst was detected in both X-ray and optical wavelengths. Its energy-dependent…
We present a study of the distribution of asymptotic burst oscillation periods for a sample of 26 bursts from 4U 1636-53 observed with the Rossi X-ray Timing Explorer (RXTE). The burst sample includes both archival and proprietary data and…
We study changes of the galactic cosmic ray (GCR) intensity for the ending period of the solar cycle 23 and the beginning of the solar cycle 24 using neutron monitors experimental data. We show that an increase of the GCR intensity in 2009…
We present X-ray and infrared observations of the X-ray source CXOGC J174536.1-285638. Previous observations suggest that this source may be an accreting binary with a high-mass donor (HMXB) or a colliding wind binary (CWB). Based on the…
The isolated neutron star RX J0806.4-4123 was observed with XMM-Newton in November 2000. The data from the three EPIC instruments allowed us (i) to derive an improved X-ray position to an accuracy of 2-3'', (ii) to accumulate the first…
We report on analysis of X-ray, optical and radio observations of the previously overlooked X-ray source 2CXO\,J174517.0$-$321356 located just 3.2$^{\circ}$ away from the Galactic center. Timing analysis of X-ray observations of the source…
It has long been thought that the pulsed X-ray properties of rotation-powered pulsars are stable on long time scales. However, long-term, systematic studies of individual sources have been lacking. Furthermore, dramatic X-ray variability…
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 Wide Field Cameras (WFCs) on BeppoSAX and the Proportional…