We report the kinematic shift and strength variability of the C IV broad absorption-line (BAL) trough in two high-ionization X-ray-bright quasi-stellar objects (QSOs): SDSS J085551+375752 (at zem ∼ 1.936) and SDSS ...

The conventional wisdom that the rate of incidence of Mgii absorption systems, dN/dz (excluding “associated systems” having a velocity βc relative to the active galactic nucleus (AGN) of less than ∼5000 km s⁻¹.), is totally ...

Based on a recently started programme, we report the first search for intranight optical variabil- ity (INOV) among radio-quiet ‘weak-line-quasars’ (RQWLQs). Eight members of this class were observed on 13 nights in the ...

This is continuation of our programme to search for the elusive radio-quiet BL Lacs, by carrying out a systematic search for intranight optical variability (INOV) in a subset of ‘weak emission line quasars’ which are ...

We obtained Sloan Digital Sky Survey spectra for a set of 37 radio-quiet quasars [(radio-quiet quasi-stellar objects (RQQSOs)] that had been previously examined for rapid small-scale optical variations, or microvariability. ...

We have developed analysis tools to search for quasi periodic oscillations in light curves from active galactic nuclei, using the following time series techniques: Wavelets, periodogram, Lomb–Scargle periodogram, structure ...