This work explores data from a few surveys, most notably the serendipitous catalogue from the NASA SWIFT mission that made use of the NUV/optical camera UVOT (originally designed to pinpoint the location of Gamma Ray Bursts). We select a sample of 10452 stars, cross matched with Gaia DR2 and 2MASS data, covering a large spectral window, from NUV to NIR. We compare these data with generic dust extinction models that parameterise the wavelength dependence into the steepness of the law, the net extinction in the V band (Av), and the strength of the prominent NUV bump. We recover well known

Up to 98% of all single stars will eventually become white dwarfs - stars that link the history and future evolution of the Galaxy, and whose previous evolution is engraved in their interiors. Those interiors can be studied using asteroseismology, utilizing stellar pulsations as seismic waves. The pulsational instability strips of DA and DB white dwarf stars are pure, allowing for the important generalization that their interior structure represents that of all DA and DB white dwarfs. This is not the case for the hottest pulsating white dwarfs, the GW Vir stars: only about 50% of white

We present the low-resolution transmission spectra of the puffy hot Jupiter HAT-P-65b (0.53 MJup, 1.89 RJup, Teq = 1930 K), based on two transits observed using the OSIRIS spectrograph on the 10.4 m Gran Telescopio CANARIAS. The transmission spectra of the two nights are consistent, covering the wavelength range 517–938 nm and consisting of mostly 5 nm spectral bins. We perform equilibrium-chemistry spectral retrieval analyses on the jointly fitted transmission spectrum and obtain an equilibrium temperature of 1645 (-244+255) K and a cloud coverage of 36 (-17+23) %, revealing a relatively

The most extreme electromagnetic radiation that can be observed is known as very high energy gamma rays (VHE, E>100 GeV). It is the last window open to the Universe, thanks to the development of the Cherenkov telescopes. The extragalactic VHE sky is still nowadays vastly unexplored, only composed of around 80 known sources. The great majority of them are classified as blazars, a type of Active Galactic Nuclei (AGN) whose relativistic jets point in the direction of the Earth boosting their emission. While the observation of the gamma-ray emission is crucial to understand the extreme physical

Blazars, Active Galactic Nuclei (AGN) whose relativistic jets point in the direction of the Earth, dominate the VHE (VHE, E>100 GeV) gamma-ray extragalactic sky. One of the most famous archetypical VHE gamma-ray emitters is the blazar Markarian 501 (Mrk 501). During July 2014, the source displayed a strong flare detected across all wavelengths from VHE to the optical band. In particular, it is especially interesting that the source reached the maximum flux and harder spectrum measured in the X-ray band, compatible with the most extreme historical flare from this source. On 2014 July 19

Astronomers from the Agrupación Astrónomica de Sabadell together with the Telescopic Operations Technicians of the Instituto de Astrofísica de Canarias, Marta Puig Subirà and Miguel Rodríguez Alarcón, have detected the transit of the exoplanet WASP-156b, catalogued as a high priority objective by the Exoclock project. The depth of the detected transit was only 6 millimagnitudes and will contribute to improve the ephemerides available for the ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) mission of the European Space Agency. Exoclock project: Kokori, A., Tsiaras, A