We present low-radio-frequency follow-up observations of AT 2017gfo, the electromagnetic counterpart of GW170817, which was the first binary neutron star merger to be detected by Advanced LIGO-Virgo. These data, with a central frequency of 144 MHz, were obtained with LOFAR, the Low-Frequency Array. The maximum elevation of the target is just 13 ${_

We use the Binary Population and Spectral Synthesis models to test the recent suggestion that red supergiants can provide an accurate age estimate of a coeval stellar population that is unaffected by interacting binary stars. Ages are estimated by using both the minimum luminosity of red supergiants and the mean luminosity of red supergiants in a

We present an optical, X-ray, and γ-ray study of 1SXPS J042749.2-670434, an eclipsing X-ray binary that has an associated γ-ray counterpart, 4FGL J0427.8-6704. This association has led to the source being classified as a transitional millisecond pulsar (tMSP) in an accreting state. We analyse 10.5 yr of Fermi LAT data and detect a γ-ray eclipse at

Due to their close proximity, the Large and Small Magellanic Clouds (LMC/SMC) provide natural laboratories for understanding how galaxies form and evolve. With the goal of determining the structure and dynamical state of the SMC, we present new spectroscopic data for ∼3000 SMC red giant branch stars observed using the AAOmega spectrograph at the

Mapping millimetre continuum emission has become a key issue in modern multi-wavelength astrophysics. In particular, spectrum imaging at low-frequency resolution is an asset for characterising the clusters of galaxies via the Sunyaev-Zel'dovich effect. In this context, we have built a ground-based spectrum-imager named KIDs Interferometer Spectrum

We use Gaia DR2 systemic proper motions of 45 satellite galaxies to constrain the mass of the Milky Way using the scale-free mass estimator of Watkins et al. (2010). We first determine the anisotropy parameter β, and the tracer satellites' radial density index γ to be β = $-0.67^{+0.45}_{-0.62}$ and γ = 2.11 ± 0.23. When we exclude possible former