Coronal Multi-channel Polarimeter at the Lomnicky Peak Observatory

Abstract

Abstract. Coronal Multi-channel Polarimeter (CoMP-S), developed by HAO/NCAR, has been introduced to regular operation at the Lomnicky Peak Observatory (High Tatras in northern Slovakia, 2633 m a.s.l.) of the Astronomical Institute of Slovak Academy of Sciences. We present here the technical parameters of the current version of the instrument and its potential for observations of prominences in the visual and near-IR spectral regions. The first results derived from observations of prominences in the Hα emission line taken during a coordinated observing campaign of several instruments in October 2012 are shown here. Keywords. solar instrumentation, spectroscopy, prominencesThe Coronal Multi-channel Polarimeter (CoMP-S) was installed on the coronagraph (Lexa, 1966) of the Lomnicky Peak Observatory of the Astronomical Institute of SAS in March 2011 and nowadays it performs regular observations. The CoMP-S instrument (Kučera et al., 2011) is based on the concept of the CoMP instrument installed nowadays at the Maona Loa Observatory (Tomczyk et al., 2008). Its core is a tunable 4-stage Lyot filter equipped with a Stokes polarimeter. It can operate in visible and near IR wavelength ranges from 500 to 1100 nm. This broad interval is allowed due to the latest achievements in polarizing materials: birefringent material VIS700BC4 by CODIXX and super-achromatic APSAW half-plates by ASTROPRIBOR. The following emission spectral lines of corona -Fe XIV 530.3 nm, Ca XV 569.5 nm, Fe X 637.5 nm, Fe XI 789.2 nm, Fe XIII 1074.7, 1079.8 nm -and prominences -He I 587.6 nm, H I 656.3 nm, Ca II 854.2 nm, He I 1083.0 nm can be observed. The Lyot filter bandpass width (FWHM) varies from 0.028 to 0.13 nm and its free spectral range is between 0.50 and 2.5 nm. Two orthogonal polarization states slightly shifted in wavelength are acquired simultaneously by two separate detectors. This allows subtraction of scattered light. The pco.edge sCMOS cameras by PCO are giving final image sampling of 0.33 arcsec/pixel and the FoV of 860×680 acrsecs (for wavelength of 656 nm).Examples of the CoMP-S observations are shown in Fig. 1. The data were taken during the HOP186 coordinated campaign "Mass loading of quiescent prominences from multiwavelength observations". A quiescent prominence was observed in the Hα spectral line tuning the filter to 9 positions across the spectral profile with four individual polarizations per wavelength step. The detector exposure time was 50 ms. Reduction has been done only in the Stokes I profile with binning of 4×4 pixels leading to the final spatial sampling of 1.3 arcsecs. Each spectral profile detected with maximum intensity greater than 4000 521 at https://www.cambridge.org/core/terms. https://doi

Signatures of the non-Maxwellianκ-distributions in optically thin line spectra

“…Here, the ratio is usable up to higher densities of up to log(n e /cm 3 ) ≈ 9.5, compared to the original paper of Flower & Pineau des Forets (1973). These lines can be measured by spectrographs mounted on the ground-based coronagraphs, such as the Coronal Multichannel Polarimeter (COMP-S) instrument being installed at the Lomnicky Peak observatory (Tomczyk et al 2007;Tomczyk & McIntosh 2009;Schwartz et al 2012Schwartz et al , 2014.…”

Transmission profile of the Dutch Open Telescope Hα Lyot filter

“…To reconcile an existing discrepancy we suggest two theoretical transmission profiles of the DOT Hα Lyot filter more compatible with observations. A method suggested here can be applied to indirect testing of transmission profiles of Lyot filters implemented, e.g., in the Narrow-band Filter Imager on-board Hinode (Kosugi et al 2007) or the Coronal Multichannel Polarimeter installed recently on the Lomnicky Peak Observatory (Kučera et al 2010;Schwartz et al 2012).…”