Elmer is a visible imager and spectrograph for the GTC. Elmer Optics has been exhaustively tested at different steps, from the blanks to the final assemblies in order to guarantee the fulfillment with the required performance. In this contribution, we describe the tests done to the different optical components until now. Blank testing, WFE Image

We study the K-correction for the case of emission lines formed in the X-ray-illuminated atmosphere of a Roche lobe-filling star. We compute the K-correction as a function of the mass ratio q and the disk flaring angle α using a compact binary code in which the companion's Roche lobe is divided into 105 resolution elements. We also study the effect

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS

The black hole transient V404 Cygni exhibited a bright outburst in June 2015 that was intensively followed over a wide range of wavelengths. Our team obtained high time resolution optical spectroscopy (! ˜ ! 90 s), which included a detailed coverage of the most active phase of the event. We present a data base consisting of 651 optical spectra

The light curve of the outburst of Comet P/Metcalf-Brewington (1991 I) is investigated. The parameters of the light curve are quite uncertain as it may be fitted both in terms of variation with heliocentric distance and exponential decay with time however, after maximum a empirical fit of m1 = 4.1 + 5 log Delta + 14.8 log r gives a good fit to the

Using the spectroscopic catalogue of the Sloan Digital Sky Survey Data Release 10, we have explored the abundance of satellites around a sample of 254 massive (1011 M⋆ 2 × 1011 M⊙) local (z 0.025) galaxies. We have divided our sample into four morphological groups (E, S0, Sa, Sb/c). We find that the number of satellites with M⋆ ≳ 109 M⊙ and R 3