C.~U. Keller

Latest

• VizieR Online Data Catalog: CS Cha B spectrum (Haffert+, 2020)
• IRDAP: SPHERE-IRDIS polarimetric data reduction pipeline
• VizieR Online Data Catalog: A planetary-mass companion to a solar-type star (Bohn+, 2020)
• VizieR Online Data Catalog: Discovery of a resolved disk around Wray 15-788 (Bohn+, 2019)
• Multiplexed holographic aperture masking with liquid-crystal geometric phase masks
• On-sky results of the Leiden EXoplanet Instrument (LEXI)
• The Single-mode Complex Amplitude Refinement (SCAR) coronagraph: II. Lab verification, and toward the characterization of Proxima b
• SPEX: a highly accurate spectropolarimeter for atmospheric aerosol characterization
• SPEX: the Spectropolarimeter for Planetary Exploration
• Investigating circular patterns in linear polarization observations of Venus
• The SPEX-airborne multi-angle spectropolarimeter on NASA's ER-2 research aircraft: capabilities, data processing and data products
• The Leiden EXoplanet Instrument (LEXI): a high-contrast high-dispersion spectrograph
• A ``Fast and Furious''' solution to the low-wind effect for SPHERE at the VLT
• Designing and testing the coronagraphic Modal Wavefront Sensor: a fast non-common path error sensor for high-contrast imaging
• Magnetic field topology and chemical spot distributions in the extreme Ap star HD 75049
• Atmospheric aerosol characterization with a ground-based SPEX spectropolarimetric instrument
• Surprising detection of an equatorial dust lane on the AGB star IRC+10216
• Use of neural networks in ground-based aerosol retrievals from multi-angle spectropolarimetric observations
• Atmospheric aerosol characterization with a ground-based SPEX spectropolarimetric instrument
• Five-dimensional optical instrumentation: combining polarimetry with time-resolved integral-field spectroscopy
• LOUPE: Spectropolarimetry of the Earth from the surface of the Moon
• Snapshot coherence-gated direct wavefront sensing for multi-photon microscopy
• Towards Polarimetric Exoplanet Imaging with ELTs
• Instrumental polarisation at the Nasmyth focus of the E-ELT
• Analysis and interpretation of 15 quarters of Kepler data of the disintegrating planet KIC 12557548 b
• Imaging the circumstellar environment of the young T Tauri star SU Aurigae
• Crowdsourced aerosol measurements using smartphone spectropolarimeters
• Remote sensing of atmospheric aerosols with the SPEX spectropolarimeter
• Iterative linear focal-plane wavefront correction
• Three-dimensional magnetic and abundance mapping of the cool Ap star HD 24712 . I. Spectropolarimetric observations in all four Stokes parameters
• Are there tangled magnetic fields on HgMn stars?
• The color dependent morphology of the post-AGB star HD 161796
• Observing Circumstellar Neighbourhoods with the Extreme Polarimeter
• Sterrekundig Instituut Utrecht: The Last Years
• Observing the Earth as an exoplanet with LOUPE, the lunar observatory for unresolved polarimetry of Earth
• A spectro-polarimetric integral field spectrograph for EPICS-EPOL
• Evidence for the disintegration of KIC 12557548 b
• Searching for signs of habitability with LOUPE, the Lunar Observatory of Unresolved Polarimetry of Earth
• The extreme polarimeter: design, performance, first results and upgrades
• Constraining the circumbinary envelope of Z Canis Majoris via imaging polarimetry
• FOAM: the modular adaptive optics framework
• Data driven identification and aberration correction for model-based sensorless adaptive optics
• iSPEX: everybody can measure atmospheric aerosols with a smartphone spectropolarimeter
• iSPEX: the creation of an aerosol sensor network of smartphone spectropolarimeters
• Multiwavelength imaging polarimetry of Venus at various phase angles
• Observing the Earth as an exoplanet
• SPEX2Earth, a novel spectropolarimeter for remote sensing of aerosols and clouds
• Direct imaging of a massive dust cloud around R Coronae Borealis
• Magnetism, chemical spots, and stratification in the HgMn star ensuremathϕ Phoenicis
• Innovative Imaging of Young Stars: First Light ExPo Observations
• New Insights into Stellar Magnetism from the Spectropolarimetry in All Four Stokes Parameters
• Signatures of Water Clouds on Exoplanets: Numerical Simulations.
• Data Reduction Approach for the Extreme Polarimeter
• Simulating Polarized Light from Exoplanets
• The Polarization Optics for the European Solar Telescope
• Imaging polarimetry of circumstellar environments with the Extreme Polarimeter
• Imaging polarimetry of protoplanetary disks: feasibility and usability
• The polarization optics for the European Solar Telescope (EST)
• The case for spectropolarimetry with SPEX on EJSM
• Polarimetric Measurements of Protoplanetary Disks with ExPo
• A Brief History of the Second Solar Spectrum
• Polarimetry from the Ground Up
• SOLIS Vector Spectromagnetograph: Status and Science
• The Prototype of the Small Synoptic Second Solar Spectrum Telescope (S5̂T)
• An analytical model to demonstrate the reliability of reconstructed `active longitudes'.
• Design of a laboratory simulator to test exoplanet imaging polarimetry
• The Extreme Polarimeter (ExPo): design of a sensitive imaging polarimeter
• New Observations of the Magnetic Vector Field across the Solar Disk
• Design Options for the Extreme Polarimeter (ExPo)
• Science Goals of the Extreme Polarimeter (ExPo)
• Seething Horizontal Magnetic Fields in the Quiet Solar Photosphere
• High-Resolution Surface Observations and What They Can Tell MHD Simulations
• SOLIS-VSM Solar Vector Magnetograms
• The Ba II 4554 / Hensuremathβ Imaging Polarimeter for the Dutch Open Telescope
• C3Po --- The Ultimate Focal Plane Array for Imaging Polarimetry from 200 nm to 20 ensuremathμm
• Reduction of SOLIS/Vector Spectromagnetograph He I 1083 nm Observations
• SOLIS-VSM Synoptic Products
• Evershed Flow of CO at Different Depths in a Sunspot Penumbra.
• High-accuracy Multiangle Spectropolarimetric Imaging Concept for Aerosol Remote Sensing from Space
• Measurement Scale of the SOLIS Vector Spectromagnetograph
• SOLIS-VSM Longitudinal Magnetogram Calibration
• Solar and Space Weather Radiophysics - Current Status and Future Developments
• Calibration and Data Analysis for the SOLIS-VSM
• The SOLIS Vector-Spectromagnetograph (VSM)
• Polarimetry with the Advanced Technology Solar Telescope
• Polarimetry with the ATST (Invited review)
• Solar observing facilities
• The SOLIS Vector-Spectromagnetograph
• Observational Signatures of a Solar Small-Scale Global Dynamo
• Preliminary tests of a low-cost solar infrared adaptive optics system
• Stokes Inversion Techniques for the SOLIS-VSM
• High Resolution Polarimetry and the Need for a Large-Aperture Solar Telescope
• Solar Chromospheric Magnetic Fields
• The Advanced Technology Solar Telescope
• The SOLIS Vector-Spectromagnetograph (VSM)
• Evolution of small-scale magnetic fields from combined adaptive optics and phase-diverse speckle imaging
• 5,000 by 5,000 Spatial by 15,000 Spectral Resolution Elements: First Astronomical Observations with a Novel 3-D Detector
• Infrared lines as probes of solar magnetic features. XV. Evershed flow in cool, weak penumbral fields
• Scattering polarization in the chromosphere
• Asteroseismology from equivalent widths: a test of the sun
• SOLIS Instrumentation Aspects
• The Procyon campaign: Observations from Kitt Peak
• Center-to-limb variation of the second solar spectrum.
• Asteroseismology via equivalent widths - tests on Procyon, Eta Bootis, and Alpha Trianguli.
• The Flare Genesis Experiment
• The Second Solar Spectrum
• Weak Magnetic Fields in the Network
• Infrared Capabilities of the Large Earth-Based Solar Telescope (LEST)
• Lest Detector and Data Acquisition System - Part One - Specifications
• LEST detector and data acquisition systems.
• Visible and Near Infrared Polarimetry with lest
• Visible and near-infrared polarimetry with LEST.
• High spatial resolution observations of solar magnetic fields
• Some aspects of polarimetry with LEST
• Speckle techniques for spectroscopic observations
• Application of Differential Speckle Imaging to Solar Polarimetry
• Demodulation of all four Stokes parameters with a single CCD - ZIMPOL II. Conceptual design.
• GAP: yet another image processing system for solar observations.
• Round table discussion.
• Zürich Imaging Stokes Polarimeter - ZIMPOL I. Design review.
• High spatial resolution polarimetry using filtergrams.
• Inversion of Stokes V profiles: The structure of solar magnetic fluxtubes and its dependence on the filling factor.
• Two-dimensional polarimeter with CCD image sensors and piezo-elastic modulators.
• Empirical Photospheric Fluxtube Models from Inversion of Stokes V Data
• High resolution photographic Stokes polarimetry of small scale magnetic flux (poster)
• Restoration of distorted images as a variational problem: a dynamic programming approach