The 1.5 meter solar telescope GREGOR

Abstract

The 1.5 m telescope GREGOR opens a new window to the understanding of solar small-scale magnetism. The first light instrumentation includes the Gregor Fabry Pérot Interferometer (GFPI), a filter spectro-polarimeter for the visible wavelength range, the GRating Infrared Spectro-polarimeter (GRIS) and the Broad-Band Imager (BBI). The excellent performance of the first two instruments has already been demonstrated at the Vacuum Tower Telescope. GREGOR is Europe's largest solar telescope and number 3 in the world. Its all-reflective Gregory design provides a large wavelength coverage from the near UV up to at least 5 microns. The field of view has a diameter of 150 . GREGOR is equipped with a high-order adaptive optics system, with a subaperture size of 10 cm, and a deformable mirror with 256 actuators. The science goals are focused on, but not limited to, solar magnetism. GREGOR allows us to measure the emergence and disappearance of magnetic flux at the solar surface at spatial scales well below 100 km. Thanks to its spectro-polarimetric capabilities, GREGOR will measure the interaction between the plasma flows, different kinds of waves, and the magnetic field. This will foster our understanding of the processes that heat the chromosphere and the outer layers of the solar atmosphere. Observations of the surface magnetic field at very small spatial scales will shed light on the variability of the solar brightness.

Magnetic fields of opposite polarity in sunspot penumbrae

“…With the integration of the scanning mechanism in April 2014, the IR spectropolarimeter of the new 1.5 m solar telescope GREGOR (von der Lühe et al 2001;Schmidt et al 2012;Denker et al 2012) has become fully operational. Using the GREGOR Adaptive Optics System (GAOS, Berkefeld et al 2012), we observed the disk passage of several active regions between April and July 2014 (see Table A.2 for a list of the sunspots observed in the IR).…”

Prospects of Solar Magnetometry—From Ground and in Space

“…The 1.5 m GREGOR telescope on Tenerife, Spain, is the currently largest European solar telescope (e.g., Schmidt et al 2012, and further papers in the special issue of AN Vol. 333, Issue 9).…”

A Non-Linear Magnetic Field Calibration Method for Filter-Based Magnetographs by Multilayer Perceptron

“…Up to now, the instruments measuring solar magnetic fields can be classified as filter-based magnetographs (e.g. the Narrowband Filter Imager onboard Hinode (Tsuneta et al 2008) and the Solar Magnetic Field Telescope (SMFT) installed at Huairou Solar Observing Station (HSOS) (Ai 1987)), the spectral magnetographs such as the Spectropolarimeter (SP) onboard Hinode and the GREGOR Infrared Spectrograph (GRIS) on the GERGOR telescope installed at the Observatorio del Teide (OT) (Schmidt et al 2012), and the combination of the above two, for instance the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (Schou et al 2012) and the in-development two-dimensional real-time spectrograph (Deng & Zhang 2009).…”