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Category/Subcategory: Natural Sciences/Astronomy

Experimental results for infrared aberration tracking using a correlation algorithm on two star extended field

Author: Narsireddy Anugu
We report an experimental results of different correlation algorithms for an extended source wavefront sensor.

Views: 428

Observational evidence for variations of the acoustic cutoff frequency with height in the solar atmosphere

Author: Aneta Wisniewska
Direct evidence for the existence of an acoustic cuto frequency in the solar atmosphere is given by observations performed by using the HELioseismological Large Regions Interferometric DEvice operating on the Vacuum Tower Teles ... more

Views: 354

Stellar magnetic activity and variability of oscillation parameters - An investigation of 24 solar-like stars observed by Kepler

Author: René Kiefer
Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with its activity cycle and these changes provide diagnostics ... more

Views: 439

Validation of Spherical Born Approximation Sensitivity Functions for Measuring Deep Solar Meridional Flow

Author: Vincent Böning
Accurate measurements of deep solar meridional flow are of vital interest for understanding the solar dynamo. In this paper, we validate a recently developed method for obtaining sensitivity functions (kernels) for travel-time mea ... more

Views: 377

The GREGOR Fabry‐Pérot Interferometer (GFPI) ‐ Technical Innovations and Results achieved in 2013

Author: Klaus Gerhard Puschmann
This paper shall provide a summary of not yet published technical innovations to the GREGOR Fabry-Pérot Interferometer (GFPI) at the 1.5m GREGOR Solar Telescope (Europe's largest solar telescope) that I implemented in 2013 as the ... more

Views: 1062

GRAVITY near infrared multiple beams analysing system: software and characterization results

Author: Narsireddy Anugu
We report the status and the characterization results of the GRAVITY acquisition camera.

Views: 447

Workshop Report: A New Synoptic Solar Observing Network

Author: Markus Roth
Since all space weather originates in and on the Sun, forecasters need continuous, long-term, consistent, and reliable solar data as a foundation for useful predictions. An effective strategy to obtain nearly continuous solar data ... more

Views: 381

Sensitivity Kernels for Flows in Time-Distance Helioseismology: Extension to Spherical Geometry

Author: Vincent Böning
We extend an existing Born approximation method for calculating the linear sensitivity of helioseismic travel times to flows from Cartesian to spherical geometry. This development is necessary for using the Born approximation for ... more

Views: 548

Measurement of the VLT pupil motions using a 2 × 2 lenslet evaluated aberrations

Author: Narsireddy Anugu
We present the telescope pupil tracking strategy for the GRAVITY interferometer.

Views: 390

Inversions for Deep Solar Meridional Flow Using Spherical Born Kernels

Author: Vincent Böning
The solar meridional flow is a crucial ingredient in modern dynamo theory. Seismic estimates of this flow have, however, been contradictory in deeper layers below about $0.9\,R_\odot$. Results from time-distance helioseismology h ... more

Views: 754