The problem of anomaly detection in astronomical surveys is becoming increasingly important as data sets grow in size. We present the results of an unsupervised anomaly detection method using a Wasserstein generative adversarial network (WGAN) on nearly one million optical galaxy images in the Hyper Suprime-Cam (HSC) survey. The WGAN learns to

We describe and test the fiducial covariance matrix model for the combined two-point function analysis of the Dark Energy Survey Year 3 (DES-Y3) data set. Using a variety of new ansatzes for covariance modelling and testing, we validate the assumptions and approximations of this model. These include the assumption of Gaussian likelihood, the

We perform high-resolution cosmological hydrodynamic simulations to study the formation of the first galaxies that reach the masses of 10 8 - 9 h -1 M ⊙ at z = 9. The resolution of the simulations is high enough to resolve minihaloes and allow us to successfully pursue the formation of multiple Population (Pop) III stars, their supernova (SN)

Elemental abundances of the most metal-poor stars reflect the conditions in the early Galaxy and the properties of the first stars. We present a spectroscopic follow-up of two ultra-metal-poor stars ([Fe/H] < -4.0) identified by the survey Pristine: Pristine 221.8781+9.7844 and Pristine 237.8588+12.5660 (hereafter Pr 221 and Pr 237, respectively)

We report on the visible LGS-AO experimental facility which we are building to be installed at the 1m ESA Optical Ground Station at Observatorio del Teide, Tenerife, Canary Islands. We focus on the system aspects related to optics. The instrument will be a novel facility to perform strategic LGS-AO technology R&D in future years, demonstrating a 50

In this new era of extensive variability surveys, classical pulsators such as RR Lyrae stars (RRLs) and Classical Cepheids play a crucial role. We focus our attention on the use of RRLs as tracers of the oldest stellar populations of the Galactic halo (Halo) and we compare their properties to those hosted by nearby Milky Way (MW) satellites. These