The GREGOR Infrared Spectrograph (GRIS) can perform spectropolarimetric observations in the infrared. The spectrograph has a Czerny-Turner design and offered traditional long-slit observations since 2014. Later on, in 2018, it was upgraded with an Integral Field Unit (IFU) based on a slicer mirror, which has slicers of 100-μm width. The latter

Infrared instruments for astronomy require many bearings for motion that must move in cryogenic conditions. There are poor and expensive options for this, and the companies with qualified bearings only supply after a long time. To attend these constrains, the Instituto de Astrofísica de Canarias (IAC) started to develop a procedure to upgrade

Transmission spectroscopy has been a workhorse technique used over the past two decades to constrain the physical and chemical properties of exoplanet atmospheres 1–5. One of its classical key assumptions is that the portion of the atmosphere it probes—the terminator region—is homogeneous. Several works from the past decade, however, have put this

The Sun's convective envelope generates, by dynamo effect, a surface magnetic field whose strength evolves on an 11-year cycle, with a change in polarity at the end of each cycle. Similar activity cycles exist in other solar-type stars, influencing the stars' dynamics, including the properties of acoustic oscillations, which are excited by

Context. Three-dimensional time-dependent simulations of stellar atmospheres are essential to study the surface of stars other than the Sun. These simulations require the opacity binning method to reduce the computational cost of solving the radiative transfer equation down to viable limits. The method depends on a series of free parameters, among

Context. Three-dimensional time-dependent simulations of stellar atmospheres are essential to study the surface of stars other than the Sun. These simulations require the opacity binning method to reduce the computational cost of solving the radiative transfer equation down to viable limits. The method depends on a series of free parameters, among