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We present timing and spectral analysis of emph{Swift}$-$XRT and emph{RXTE}$-$PCA observations of the transient Be/X-ray pulsar SWIFT J0513.4--6547 during its outburst in 2009 and its rebrightening in 2014. From 2009 observations, short term spin-up rate of the source after the peak of the outburst is found to have about half of the value measured at the peak of the outburst by Coe et al. When the source is quiescent between 2009 and 2014, average spin-down rate of the source is measured to be $sim 1.52 times 10^{-12}$ Hz s$^{-1}$ indicating a surface dipole magnetic field of $sim 1.5 times 10^{13}$ Gauss assuming a propeller state. From 2014 observations, short term spin-down rate of the source is measured to be about two orders smaller than this long-term spin-down rate. The orbit of the source is found to be circular which is atypical for transient Be/X-ray binary systems. Hardness ratios of the source correlate with the X-ray luminosity up to $8.4times 10^{36}$ erg s$^{-1}$ in 3-10 keV band, whereas for higher luminosities hardness ratios remain constant. Pulsed fractions are found to be correlated with the source flux. Overall emph{Swift}$-$XRT and emph{RXTE}$-$PCA energy spectrum of the source fit equally well to a model consisting of blackbody and power law, and a model consisting of a power law with high energy cut-off. From the pulse phase resolved spectra and pulse phase resolved hardness ratios obtained using emph{RXTE}$-$PCA, it is shown that spectrum is softer for the phases between the two peaks of the pulse.
We analyze emph{RXTE} and emph{Swift} observations of SWIFT J1729.9$-$3437 after its outburst from 2010 July 20 to 2010 August 12. We calculate a spin frequency and spin frequency derivative of $1.8734(8) times 10^{-3}$ Hz and $6.42(6) times 10^{-12}
The 4th IBIS/ISGRI survey lists 723 hard X-ray sources many still unidentified. We cross-correlated the list of the sources included in the 4th IBIS catalogue with the Swift/XRT data archive, finding a sample of 20 objects for which XRT data could he
We present results from a long-term monitoring campaign on the TeV binary LSI +61 303 with VERITAS at energies above 500 GeV, and in the 2-10 keV hard X-ray bands with RXTE and Swift, sampling nine 26.5 day orbital cycles between September 2006 and F
We present contemporaneous X-ray, ultraviolet, optical and near-infrared observations of the black hole binary system, Swift J1753.5-0127, acquired in 2012 October. The UV observations, obtained with the Cosmic Origins Spectrograph on the Hubble Spac
Supernova (SN) 2018cow (or AT2018cow) is an optical transient detected in the galaxy CGCG 137-068. It has been classified as a SN due to various characteristics in its optical spectra. The transient is also a bright X-ray source. We present results o