Want a PEPSI? Performance status of the recently commissioned high-resolution spectrograph and polarimeter for the 2x8.4m Large Binocular Telescope

Klaus G. Strassmeier; I. Ilyin; M. Weber; A. Järvinen; M. Woche; S. Järvinen; D. Sablowski; M. Mallonn; E. Keles; T. Carroll; M. C. Johnson; C. Bender; R. M. Wagner; C. Veillet

doi:10.1117/12.2311627

6 July 2018 Want a PEPSI? Performance status of the recently commissioned high-resolution spectrograph and polarimeter for the 2x8.4m Large Binocular Telescope

Klaus G. Strassmeier, I. Ilyin, M. Weber, A. Järvinen, M. Woche, S. Järvinen, D. Sablowski, M. Mallonn, E. Keles, T. Carroll, M. C. Johnson, C. Bender, R. M. Wagner, C. Veillet

Author Affiliations +

Proceedings Volume 10702, Ground-based and Airborne Instrumentation for Astronomy VII; 1070212 (2018) https://doi.org/10.1117/12.2311627
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

PEPSI is the new fiber-fed and stabilized “Potsdam Echelle Polarimetric and Spectroscopic Instrument” for the Large Binocular Telescope (LBT). It covers the entire optical wavelength range from 384 to 913 nm in three exposures at resolutions of either R=λ/▵λ=50,000, 130,000 or 250,000. The R=130,000 mode can also be used with two dual-beam Stokes IQUV polarimeters. The 50,000-mode with its 12-pix sampling per resolution element is our “bad seeing” or “faint-object” mode. A robotic solar-disk-integration (SDI) telescope feeds solar light to PEPSI during day time and a 450-m fiber feed from the 1.8m VATT can be used when the LBT is busy otherwise. CCD characterization and a removal procedure for the spatial fixed-pattern noise were the main tasks left from the commissioning phase. Several SDI spectral time series with up to 300 individual spectra per day recovered the well-known solar 5-minute oscillation at a peak of 3 mHz (5.5min) with a disk-integrated radial-velocity amplitude of only 47 cm/s. Spectral atlases for 50 bright benchmark stars including the Sun were recently released to the scientific community, among them the ancient planet- system host Kepler-444. These data combine PEPSI’s high spectral resolution of R=250,000 with signal-to-noise ratio (S/N) of many hundreds to even thousands covering the entire optical to near-infrared wavelength range from 384 to 913 nm. Other early science cases were exoplanet transits including TRAPPIST-1, a spectrum of Boyajian's star that revealed strong and structured but stable ISM Na D lines, a spectrum of Oph allowing a redetermination of the ISM Li line doublet, and a first Doppler image of the young solar analog EK Dra that revealed starspots with solar-like penumbrae.

Conference Presentation

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Klaus G. Strassmeier, I. Ilyin, M. Weber, A. Järvinen, M. Woche, S. Järvinen, D. Sablowski, M. Mallonn, E. Keles, T. Carroll, M. C. Johnson, C. Bender, R. M. Wagner, and C. Veillet "Want a PEPSI? Performance status of the recently commissioned high-resolution spectrograph and polarimeter for the 2x8.4m Large Binocular Telescope", Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 1070212 (6 July 2018); https://doi.org/10.1117/12.2311627

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