475 citations · 2.5k across the 73 of their papers we have counts for
5 papers · 1 filter
Unusual Stokes V profiles during flaring activity of a delta sunspot
C. E. Fischer, C. U. Keller, F. Snik +2
We analyze a set of full Stokes profile observations of the flaring active region NOAA 10808 recorded with the Vector-Spectromagnetograph (VSM) of the SOLIS facility. We aim to qua…
Sterrekundig Instituut Utrecht: The Last Years
Christoph U. Keller
I describe the last years of the 370-year long life of the Sterrekundig Instituut Utrecht, which was the second-oldest university observatory in the world and was closed in early 2…
M&m's: An error budget and performance simulator code for polarimetric systems
Maria de Juan Ovelar, Frans Snik, Christoph U. Keller
Although different approaches to model a polarimeter's accuracy have been described before, a complete error budgeting tool for polarimetric systems has not been yet developed. Bas…
Extremely fast focal-plane wavefront sensing for extreme adaptive optics
Christoph U. Keller, Visa Korkiakoski, Niek Doelman +3
We present a promising approach to the extremely fast sensing and correction of small wavefront errors in adaptive optics systems. As our algorithm's computational complexity is ro…
Observing the Earth as an exoplanet with LOUPE, the Lunar Observatory for Unresolved Polarimetry of Earth
T. Karalidi, D. M. Stam, F. Snik +3
The detections of small, rocky exoplanets have surged in recent years and will likely continue to do so. To know whether a rocky exoplanet is habitable, we have to characterise its…