Presentation #139.06 in the session “Ground-based Optical Instrumentation and Performance”.
We present the first science results from the High Optical Resolution Spectrograph (HORuS), a cross-dispersed echelle spectrograph now in operation on the 10.4-m Gran Telescopio Canarias (GTC). The spectrograph provides a FWHM resolving power of 25,000 and coverage between 370 and 690 nm. HORuS has been mostly built with parts from a previous instrument, with a number of upgrades including a train of monolithic prisms for cross-dispersion, a fiber link, and a new CCD. The commissioning of HORuS was completed in March 2019 and over the past three semesters the instrument has been used to observe stars orbiting black holes, transiting exoplanets, planetary nebulae, star clusters in nearby galaxies, stellar streams, and extremely metal-poor stars. This presentation will highlight the varied results reported in the first publications using HORuS data.