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An inversion technique has been developed to recover LTE one-dimensional model photospheres for late-type stars from very high resolution, high signal-to-noise stellar line profiles. It is successfully applied to the Sun by using a set of…

Astrophysics · Physics 2009-10-30 Carlos Allende Prieto , Basilio Ruiz Cobo , Ramon J. Garcia Lopez

The measurement of Doppler velocities in spectroscopic solar observations requires a reference for the local frame of rest. The rotational and radial velocities of the Earth and the rotation of the Sun introduce velocity offsets in the…

Solar and Stellar Astrophysics · Physics 2015-05-27 Jaime de la Cruz Rodríguez , Dan Kiselman , Mats Carlsson

The major cornerstone of future ground-based astronomy is imaging and spectroscopy at the diffraction limit using adaptive optics. To exploit the potential of current AO systems, we have begun a survey around bright stars to study…

Astrophysics · Physics 2007-05-23 R. I. Davies , M. Lehnert , A. J. Baker , S. Rabien

The technique of High Spectral Resolution Lidar (HSRL) for atmospheric monitoring allows the determination of the aerosol to molecular ratio and can be used in UHECR Observatories using air fluorescence telescopes. By this technique a more…

Instrumentation and Methods for Astrophysics · Physics 2012-04-06 Angelika Georgakopoulou

The use of infrastructure sensor technology for traffic detection has already been proven several times. However, extrinsic sensor calibration is still a challenge for the operator. While previous approaches are unable to calibrate the…

Computer Vision and Pattern Recognition · Computer Science 2020-08-04 Laurent Kloeker , Christian Kotulla , Lutz Eckstein

High-resolution observations of the solar chromosphere at millimeter wavelengths are now possible with the Atacama Large Millimeter Array (ALMA), promising to tackle many open problems in solar physics. Observations from other ground and…

Solar and Stellar Astrophysics · Physics 2018-12-12 João M. da Silva Santos , Jaime de la Cruz Rodríguez , Jorrit Leenaarts

As the frontier of precision astronomical photometry continues to advance, correcting for time-variable atmospheric transmission becomes increasingly important. We describe an observational approach to monitoring optical attenuation due to…

Instrumentation and Methods for Astrophysics · Physics 2025-08-26 Eske M. Pedersen , Christopher W. Stubbs , Merlin Fisher-Levine , Elana K. Urbach , Erik Dennihy , Patrick Ingraham

Lidar has become a cornerstone sensing modality for 3D vision, especially for large outdoor scenarios and autonomous driving. Conventional lidar sensors are capable of providing centimeter-accurate distance information by emitting laser…

Computer Vision and Pattern Recognition · Computer Science 2024-06-12 Dominik Scheuble , Chenyang Lei , Seung-Hwan Baek , Mario Bijelic , Felix Heide

Astronomers working with faint targets will benefit greatly from improved image quality on current and planned ground-based telescopes. At present, most adaptive optic systems are targeted at the highest resolution with bright guide stars.…

Instrumentation and Methods for Astrophysics · Physics 2020-01-30 Craig Mackay

The new method for aerosol measurement using wide-field stellar photometry was originally developed for B-filter data. The dependence of VAOD (vertical aerosol optical depth) on wavelength can be used to understand the physical…

Instrumentation and Methods for Astrophysics · Physics 2025-05-06 Shefali Negi , Jan Ebr , Sergey Karpov , Jiří Eliášek

Deployment of automated ground vehicles beyond the confines of sunny and dry climes will require sub-lane-level positioning techniques based on radio waves rather than near-visible-light radiation. Like human sight, lidar and cameras…

Signal Processing · Electrical Eng. & Systems 2020-10-19 Lakshay Narula , Peter A. Iannucci , Todd E. Humphreys

Integrating conventional optics into compact nanostructured surfaces is the goal of flat optics. Despite the enormous progress of this technology, there are still critical challenges for real world applications due to a limited efficiency…

Atmospheric optical turbulence seriously limits the performance of high angular resolution instruments. An 8-night campaign of measurements was carried out at the LAMOST site in 2011, to characterize the optical turbulence. Two instruments…

Instrumentation and Methods for Astrophysics · Physics 2015-05-21 L. -Y. Liu , C. Giordano , Y. -Q. Yao , J. Vernin , M. Chadid , H. -S. Wang , J. Yin , Y. -P. Wang

We use telemetry data from the Gemini North ALTAIR adaptive optics system to investigate how well the commands for wavefront correction (both Tip/Tilt and high-order turbulence) can be forecasted in order to reduce lag error (due to…

Instrumentation and Methods for Astrophysics · Physics 2022-05-16 Rehan Hafeez , Finn Archinuk , Sébastien Fabbro , Hossen Teimoorinia , Jean-Pierre Véran

We have constructed an analytical model to simulate the behavior of an adaptive optics system coupled with a sodium laser guide star. The code is applied to a 3.6-m and 8m class telescopes. The results are given in terms of Strehl ratio and…

Astrophysics · Physics 2009-10-30 M. Le Louarn , R. Foy , N. Hubin , M. Tallon

A priori, cosmic-ray measurements offer a unique capability to determine the vertical profile of atmospheric temperatures directly from ground. However, despite the increased understanding of the impact of the atmosphere on cosmic-ray…

Atmospheric and Oceanic Physics · Physics 2021-12-10 Riádigos Irma , González-Díaz Diego , Pérez-Muñuzuri Vicente

Lidar-based object detectors are critical parts of the 3D perception pipeline in autonomous navigation systems such as self-driving cars. However, they are known to be sensitive to adverse weather conditions such as rain, snow and fog due…

Computer Vision and Pattern Recognition · Computer Science 2021-07-16 Velat Kilic , Deepti Hegde , Vishwanath Sindagi , A. Brinton Cooper , Mark A. Foster , Vishal M. Patel

In this work, sub-ppb aerosol detection is achieved by femtosecond laser filament with a single pulse energy of 4 mJ at a distance of 30 m. A concave mirror with an open aperture of 41.4 cm is employed in an off-axis optical system to focus…

The basic understanding of high-intensity femtosecond laser absorption in a solid is crucial for high-energy-density science. This multidimensional problem has many variables like laser parameters, solid target material, and geometry of the…

Deploying advanced imaging solutions to robotic and autonomous systems by mimicking human vision requires simultaneous acquisition of multiple fields of views, named the peripheral and fovea regions. Low-resolution peripheral field provides…