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Register a new userPEPSI: The high-resolution echelle spectrograph and polarimeter for the Large Binocular Telescope
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PEPSI is the bench-mounted, two-arm, fibre-fed and stabilized Potsdam Echelle Polarimetric and Spectroscopic Instrument for the 2x8.4 m Large Binocular Telescope (LBT). Three spectral resolutions of either 43 000, 120 000 or 270 000 can cover the entire optical/red wavelength range from 383 to 907 nm in three exposures. Two 10.3kx10.3k CCDs with 9-{mu}m pixels and peak quantum efficiencies of 96 % record a total of 92 echelle orders. We introduce a new variant of a wave-guide image slicer with 3, 5, and 7 slices and peak efficiencies between 96 %. A total of six cross dispersers cover the six wavelength settings of the spectrograph, two of them always simultaneously. These are made of a VPH-grating sandwiched by two prisms. The peak efficiency of the system, including the telescope, is 15% at 650 nm, and still 11% and 10% at 390 nm and 900 nm, respectively. In combination with the 110 m2 light-collecting capability of the LBT, we expect a limiting magnitude of 20th mag in V in the low-resolution mode. The R=120 000 mode can also be used with two, dual-beam Stokes IQUV polarimeters. The 270 000-mode is made possible with the 7-slice image slicer and a 100- {mu}m fibre through a projected sky aperture of 0.74, comparable to the median seeing of the LBT site. The 43000-mode with 12-pixel sampling per resolution element is our bad seeing or faint-object mode. Any of the three resolution modes can either be used with sky fibers for simultaneous sky exposures or with light from a stabilized Fabry-Perot etalon for ultra-precise radial velocities. CCD-image processing is performed with the dedicated data-reduction and analysis package PEPSI-S4S. A solar feed makes use of PEPSI during day time and a 500-m feed from the 1.8 m VATT can be used when the LBT is busy otherwise. In this paper, we present the basic instrument design, its realization, and its characteristics.
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We are developing a stable and precise spectrograph for the Large Binocular Telescope (LBT) named iLocater. The instrument comprises three principal components: a cross-dispersed echelle spectrograph that operates in the YJ-bands (0.97-1.30 microns), a fiber-injection acquisition camera system, and a wavelength calibration unit. iLocater will deliver high spectral resolution (R~150,000-240,000) measurements that permit novel studies of stellar and substellar objects in the solar neighborhood including extrasolar planets. Unlike previous planet-finding instruments, which are seeing-limited, iLocater operates at the diffraction limit and uses single mode fibers to eliminate the effects of modal noise entirely. By receiving starlight from two 8.4m diameter telescopes that each use extreme adaptive optics (AO), iLocater shows promise to overcome the limitations that prevent existing instruments from generating sub-meter-per-second radial velocity (RV) precision. Although optimized for the characterization of low-mass planets using the Doppler technique, iLocater will also advance areas of research that involve crowded fields, line-blanketing, and weak absorption lines.
We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mt Abu 1.2 m telescope, in India. Data obtained as part of the post-commissioning tests with PARAS show velocity precision better than 2m/s over a period of several months on bright RV standard stars. For observations of sigma-Dra we report 1.7m/s precision for a period of seven months and 2.1m/s for HD 9407 over a period of 2 months. PARAS is capable of a single-shot spectral coverage of 3800A - 9500A at a resolution of about 67,000. The RV results were obtained between 3800A and 6900A using simultaneous wavelength calibration with a Thorium-Argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01 - 0.02C (rms) at 25.55C, and enclosed in a vacuum vessel at pressure of 0.1 +/-0.03 mbar. The blaze peak efficiency of the spectrograph between 5000A and 6500A, including the detector, is 30%; and about 25% with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81% reflectivity) is about 7% in the same wavelength region on a clear night with good seeing conditions.
We present an analysis of polarimetric observations of standard stars performed over the period of more than three years with the RINGO3 polarimeter mounted on the Liverpool Telescope. The main objective was to determine the instrumental polarisation of the RINGO3 polarimeter in three spectral energy ranges: blue (350--640~nm), green (650--760~nm) and red (770--1000~nm). The observations were conducted between 2012 and 2016. The total time span of 1126 days was split into five epochs due to the hardware changes to the observing system. Our results should be applied to calibrate all polarimetric observations performed with the RINGO3 polarimeter.
We present a conceptual study of a large format imaging spectrograph for the Large Submillimeter Telescope (LST) and the Atacama Large Aperture Submillimeter Telescope (AtLAST). Recent observations of high-redshift galaxies indicate the onset of earliest star formation just a few 100 million years after the Big Bang (i.e., z = 12--15), and LST/AtLAST will provide a unique pathway to uncover spectroscopically-identified first forming galaxies in the pre-reionization era, once it will be equipped with a large format imaging spectrograph. We propose a 3-band (200, 255, and 350 GHz), medium resolution (R = 2,000) imaging spectrograph with 1.5 M detectors in total based on the KATANA concept (Karatsu et al. 2019), which exploits technologies of the integrated superconducting spectrometer (ISS) and a large-format imaging array. A 1-deg2 drilling survey (3,500 hr) will capture a large number of [O III] 88 um (and [C II] 158 um) emitters at z = 8--9, and constrain [O III] luminosity functions at z > 12.
HIRES will be the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 mic (goal 0.35-1.8 mic) at a spectral resolution of ~100,000. The fibre-feeding allows HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU in the NIR. Therefore, it will be able to operate both in seeing and diffraction-limited modes. ELT-HIRES has a wide range of science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Some of the top science cases will be the detection of bio signatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars (PopIII), tests on the stability of Natures fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers.
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