The GREGOR Fabry-Perot interferometer: a new instrument for high-resolution solar observations

Denker, C.; Balthasar, H.; Hofmann, Axel; González, N. Bello; Volkmer, R.

doi:10.1117/12.856830

Cited by 17 publications

(8 citation statements)

References 15 publications

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“…Examples of current filter type instruments are the Imaging Vector Magnetograph (IVM, Mickey et al 1996), the Interferometric BIdimensional Spectrometer (IBIS, Cavallini 2006), the Solar Vector Magnetograph (SVM, Gosain et al 2006), the CRisp Imaging SpectroPolarimeter (CRISP) at the SST (Scharmer et al 2008), and the GREGOR Fabry-Pérot Instrument (GFPI, Denker et al 2010). Tunable imaging spectrometers come in various flavors.…”

Section: Filter-based or Imaging Instrumentsmentioning

confidence: 99%

Measurements of Photospheric and Chromospheric Magnetic Fields

et al. 2015

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The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent, their importance for the thermodynamics in the solar photosphere is determined by the total magnetic flux. Whereas in low-flux quiet Sun regions, magnetic structures are shuffled around by the motion of granules, the high-flux areas like sunspots or pores effectively suppress convection, leading to a temperature decrease of up to 3000 K. The importance of magnetic fields to the conditions in higher atmospheric layers, the chromosphere and corona, is indisputable. Magnetic fields in both active and quiet regions are the main coupling agent between the outer layers of the solar atmosphere, and are therefore not only involved in the structuring of these layers, but also for the transport of energy from the solar surface through the corona to the interplanetary space. Consequently, inference of magnetic fields in the photosphere, and especially in the chromosphere, is crucial to deepen our understanding not only for solar phenomena such as chromospheric and coronal heating, flares or coronal mass ejections, but also for fundamental physical topics like dynamo theory or atomic physics. In this review, we present an overview of significant advances during the last decades in measurement techniques, analysis methods, and the availability of observatories, together with some selected results. We discuss the problems of determining magnetic fields at smallest spatial scales, connected with increasing demands on polarimetric sensitivity and temporal resolution, and highlight some promising future developments for their solution.Comment: Accepted for publication in "Space Science Reviews"; 42 pages, 16 figure

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Section: Filter-based or Imaging Instrumentsmentioning

confidence: 99%

Measurements of Photospheric and Chromospheric Magnetic Fields

et al. 2015

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“…Imaging spectropolarimetry is nowadays carried out with complex Fabry-Perót interferometers (FPIs). Examples include the Triple Etalon SOlar Spectrometer (TESOS) [1,2] at the Vacuum Tower Telescope (VTT), the Interferometric BIdimensional Spectropolarimeter (IBIS) [3] at the Dunn Solar Telescope (DST), the CRisp Imaging SpectroPolarimeter (CRISP) [4] at the Swedish Tower Telescope (SST), and the GREGOR Fabry-Perót Interferometer (GFPI) [5,6] at the 1.5meter GREGOR solar telescope [7][8][9] located at Observatorio del Teide, Tenerife, Spain. The next generation of FPIs is already on the horizon.…”

Section: Introductionmentioning

confidence: 99%

Measuring the etalon quality of the GREGOR Fabry–Pérot interferometer

Verma

Denker

2020

J. Astron. Telesc. Instrum. Syst.

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Imaging spectropolarimetry is an important observational tool in solar physics because of fast-cadence spectral scans with high-spectral resolution, large field-of-view, and its inherent suitability for post-facto image restoration. Fabry-Pérot etalons are the key optical elements of these instruments. Their optical quality critically defines the instrument's performance. The two etalons of the GREGOR Fabry-Pérot Interferometer (GFPI) were used for more than 10 years, raising questions about the potential deterioration of etalons coatings. We present an assessment of the etalons optical quality, describe the inspection method based on Zernike polynomials, discuss the field dependence of the finesse and its consequences for instrument design, and investigate the impact of the measurement technique to achieve plate parallelism. We find that extended exposure to sunlight affects the etalon coatings, i.e., lowering the peak transmission and leaving an imprint of the pupil of the GREGOR solar telescope on the etalon that is directly exposed to sunlight. The finesse of both etalons, however, remains high so that the impact on imaging spectropolarimetry is negligible.

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“…16,17 In 2009, the Leibniz-Institut für Astrophysik Potsdam took over the scientific responsibility for the GFPI, and the instrument was finally installed at the GREGOR telescope. 19 During the commissioning phase in 2011, the software was prepared for TCP/IP communication with external devices according to the Device Communication Protocol (DCP 20 ) and three computercontrolled translation stages (two filter sliders and one mirror stage) were integrated into the GFPI. 21 This permits automated observing and calibration procedures and facilitates easy operations during observing runs.…”

Section: Introductionmentioning

confidence: 99%

GREGOR Fabry-Pérot interferometer and its companion the blue imaging solar spectrometer

et al. 2013

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The GREGOR Fabry-Pérot Interferometer (GFPI) is one of three first-light instruments of the German 1.5-meter GREGOR solar telescope at the Observatorio del Teide, Tenerife, Spain. The GFPI allows fast narrow-band imaging and post-factum image restoration. The retrieved physical parameters will be a fundamental building block for understanding the dynamic Sun and its magnetic field at spatial scales down to ∼ 50 km on the solar surface. The GFPI is a tunable dualetalon system in a collimated mounting. It is designed for spectrometric and spectropolarimetric observations between 530-860 nm and 580-660 nm, respectively, and possesses a theoretical spectral resolution of R ≈ 250, 000. Large-format, high-cadence CCD detectors with sophisticated computer hard-and software enable the scanning of spectral lines in time-spans equivalent to the evolution time of solar features.The field-of-view (FOV) of 50 ′′ × 38 ′′ covers a significant fraction of the typical area of active regions in the spectroscopic mode. In case of Stokes-vector spectropolarimetry, the FOV reduces to 25 ′′ × 38 ′′ . We present the main characteristics of the GFPI including advanced and automated calibration and observing procedures. We discuss improvements in the optical design of the instrument and show first observational results. Finally, we lay out first concrete ideas for the integration of a second FPI, the Blue Imaging Solar Spectrometer (BLISS), which will explore the blue spectral region below 530 nm.

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The GREGOR Fabry-Perot interferometer: a new instrument for high-resolution solar observations

Cited by 17 publications

References 15 publications

Measurements of Photospheric and Chromospheric Magnetic Fields

Measurements of Photospheric and Chromospheric Magnetic Fields

Measuring the etalon quality of the GREGOR Fabry–Pérot interferometer

GREGOR Fabry-Pérot interferometer and its companion the blue imaging solar spectrometer

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