Related papers: The Be/X-ray binary A0535+26 during its recent 200…

Observations of the high-mass gamma-ray binary LS 2883/PSR B1259--63 with the Chandra X-ray Observatory during the 2011--2014 and 2014--2017 binary cycles have shown X-ray emitting clumps, presumably ejected from the binary during…

We report the X-ray spectral and timing analysis of the high mass X-ray binary EXO 2030+375 during the 2021 type II outburst. We have incorporated NuSTAR, NICER, \textit{Swift}/BAT \& \textit{Fermi}/GBM observations to carry out a…

The high-frequency peaked BL Lac PKS 2155-304 at redshift z=0.116 is a well-known VHE (>100 GeV) gamma-ray emitter. Since 2002 its VHE flux has been monitored using the H.E.S.S. stereoscopic array of imaging atmospheric-Cherenkov telescopes…

We report and study the outburst of a new transient X-ray binary (XRB) in Terzan 5, the third detected in this globular cluster, Swift J174805.3-244637 or Terzan 5 X-3. We find clear spectral hardening in Swift/XRT data during the outburst…

We present a timing and spectral analysis of the variable X-ray source 3A 1954+319. Our analysis is mainly based on an outburst serendipitously observed during INTEGRAL Key Program observations of the Cygnus region in 2008 fall and on the…

GRO J2058+42, a transient 198 second x-ray pulsar, was discovered by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory (CGRO), during a "giant" outburst in 1995 September-October. The total flux peaked…

The binary X-ray pulsar A0535+262 was observed with the Suzaku X-ray observatory, on 2005 September 14 for a net exposure of 22 ksec. The source was in a declining phase of a minor outburst, exhibiting 3--50 keV luminosity of about $3.7…

The recent discovery of a ~9.5-d period in the X-ray lightcurve of the massive X-ray binary 4U2206+54 has opened the possibility that it is a Be/X-ray binary with an unusually close orbit, which, together with its low intrinsic luminosity,…

A young and energetic pulsar powers the well-known Crab Nebula. Here we describe two separate gamma-ray (photon energy >100 MeV) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The…

We present new observations of the "supernova impostor" SN 2010da using the Chandra X-ray Observatory and the Hubble Space Telescope. During the initial 2010 outburst, the 0.3-10 keV luminosity was observed by Swift to be…

IGR J11215-5952 is a hard X-ray transient source discovered in April 2005 with INTEGRAL and a confirmed member of the new class of High Mass X-ray Binaries, the Supergiant Fast X-ray Transients (SFXTs). Archival INTEGRAL data and RXTE…

The remarkable Crab Nebula is powered by an energetic pulsar whose relativistic wind interacts with the inner parts of the Supernova Remnant SN1054. Despite low-intensity optical and X-ray variations in the inner Nebula, the Crab has been…

The BL Lac type object 1ES 2344+51.4 (redshift $z=0.044$) was one of the first sources to be included in the extreme high-peaked BL Lac (EHBL) family. EHBLs are characterised by a broadband spectral energy distribution (SED) featuring the…

We report the discovery of a 1--5~Hz X-ray flaring phenomenon observed at $>30$~mCrab near peak luminosity in the 2008 and 2011 outbursts of the accreting millisecond X-ray pulsar SAX J1808.4--3658 in observations with the \textit{Rossi…

Gamma-ray emission from the Crab Nebula has been recently shown to be unsteady. In this paper, we study the flux and spectral variability of the Crab above 100 MeV on different timescales ranging from days to weeks. In addition to the four…

[Abridged] We present more than 4 years of Swift X-ray observations of the 2013 superoutburst, subsequent decline and quiescence of the WZ Sge-type dwarf nova SSS J122221.7-311525 (SSS122222) from 6 days after discovery. Only a handful of…

We report on Swift observations of four z>2 radio-loud quasars (0212+735, 0537-286, 0836+710, and 2149-307), classified as blazars. The sources, well-known emitters at soft-medium X-rays, were detected at >5sigma with the BAT experiment in…

The Crab Nebula is one of the brightest and most stable sources in the X-ray sky. Year-scale flux variation from the object was recently revealed in the hard X-ray band by four satellites. This marked the first detection of year-scale…

XTE J1829-098 is a transient X-ray pulsar with a period of ~7.8 s. It is a candidate Be star system, although the evidence for this is not yet definitive. We investigated the twenty-year long X-ray light curve using the Rossi X-ray Timing…

In mid-January 2008, EX Lup, the prototype of the small class of eruptive variables called EXors, began an extreme outburst that lasted seven months. We observed EX Lup during about 21 h with XMM-Newton, simultaneously in X-rays and UV, on…