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We have analyzed the new Rossi X-ray Timing Explorer Proportional Counter Array data of the atoll neutron star (NS) low-mass X-ray binary (LMXB) system XB 1254-690. The colour-colour diagram shows that the source was in the high-intensity banana state. We have found two low-frequency candidate peaks with single trial significances of ~ 2.65 X 10^{-8} and ~ 7.39 X 10^{-8} in the power spectra. After taking into account the number of trials, the joint probability of appearance of these two peaks in the data set only by chance is ~ 4.5 X 10^{-4}, and hence a low-frequency QPO can be considered to be detected with a significance of ~ 4.5 X 10^{-4}, or, ~ 3.5sigma for the first time from this source. We have also done the first systematic X-ray spectral study of XB 1254-690, and found that, while one-component models are inadequate, three-component models are not required by the data. We have concluded that a combined broken-powerlaw and Comptonization model best describes the source continuum spectrum among 19 two-component models. The plasma temperature (~ 3 keV) and the optical depth (~ 7) of the Comptonization component are consistent with the previously reported values for other sources. However, the use of a broken-powerlaw component to describe NS LMXB spectra has recently been started, and we have used this component for XB 1254-690 for the first time. We have attempted to determine the relative energy budgets of the accretion disc and the boundary layer using the best-fit spectral model, and concluded that a reliable estimation of these budgets requires correlations among time variations of spectral properties in different wavelengths.
We present photometric and spectroscopic observations of the low mass X-ray binary GR Mus (XB 1254-690), and find strong evidence for the presence of a negative superhump with a period that is 2.4+/-0.3% shorter than the orbital. This provides furthe
Rossi X-ray Timing Explorer (RXTE)/Proportional Counter Array (PCA) observations of IGR J19294+1816 covering two outburst episodes are reported. The first outburst happened during MJD 54921-54925 (2009 C.E.) and the second one happened during MJD 554
We present the results from an X-ray variability study of IRAS 13224-3809. This is probably the best source for X-ray reverberation studies since it is X-ray bright, extremely variable, and it has been extensively observed with XMM-Newton. We used al
We provide new observations of the LMC X-1 O star and its extended nebula structure using spectroscopic data from VLT/UVES as well as H$alpha$ imaging from the Wide Field Imager on the Max Planck Gesellschaft / European Southern Observatory 2.2m tele
We present timing and spectral analysis of RXTE-PCA observations of SMC X-1 between January 1996 and December 2003. From observations around 30 August 1996 with a time span of $sim 6$ days, we obtain a precise timing solution for the source and resol