Optical spectrophotometry of the active galaxy PKS 0521-365 over a period of 7 years is reported, together with the analysis of IUE archival spectra. The Hα...

We compile published spectroscopic data and [O III] magnitudes of almost 500 extragalactic planetary nebulae (PNe) in 13 galaxies of various masses and...

We present a study of photometric flares on 154 low-mass (≤0.2 M ⊙) objects observed by the SPECULOOS-South Observatory from 2018 June 1 to 2020 March 23. In...

We present observations of wavelength-dependent flux ratios for four gravitational lens systems (SDSS J1650+4251, HE 0435-1223, FBQ 0951+2635, and Q 0142-100)...

We report Hubble Space Telescope observations of six gravitational lenses with the Advanced Camera for Surveys. We measured the flux ratios between the lensed...

We present Gemini Multi-Object Spectrograph (GMOS) spectroscopic observations of 95 galaxies from the Arp & Madore (1987) catalog of peculiar galaxies. These...

This paper discusses the properties of the European Large Area ISO Survey (ELAIS) 15-μm quasars and tries to establish a robust method of quasar selection for...

Here we make a new study of the behaviour of the NaI/KI column density ratio in the interstellar medium, using a sample of new observations of 28 stars obtained...

Visual and infrared light curves of the noncontact, short period, close binary system UR Tauri were obtained in 1992 November. A new ephemeris of the binary is...