Related papers: Atmospheric time constant with MASS and FADE

SI-traceable measurements of optical frequencies using International Atomic Time (TAI) do not require a local primary frequency reference, but suffer from an uncertainty in tracing to the SI second. For the measurement of the $^{87}$Sr…

The image quality from Ground-Layer Adaptive Optics (GLAO) can be gradually increased with decreased contiguous field of view. This trade-off is dependent on the vertical profile of the optical turbulence (Cn2 profiles). It is known that…

We study the impact of the atmospheric differential chromatic refraction on the measurements and precision of relative astrometry. Specifically, we address the problem of measuring the separations of close pairs of binary stars with…

A stellar hydrodynamic pulsation model has been combined with a SiO maser model in an attempt to calculate the temporal variability of SiO maser emission in the circumstellar envelope (CE) of a model AGB star. This study investigates…

In this technical communique, we propose a novel observer-based adaptive scheme to deal with the parameter estimation problem of biased sinusoidal signals. Different from the existing adaptive frequency estimation scheme, the proposed…

Adaptive optics is a technique mostly used on large telescopes. It turns out to be challenging for smaller telescopes (0.5~2m) due to the small isoplanatic angle, small subapertures and high correction speeds needed at visible wavelengths,…

In addition to the BLINC/MIRAC IR science instruments, the Magellan adaptive secondary AO system will have an EEV CCD47 that can be used both for visible AO science and as a wide-field acquisition camera. The effects of atmospheric…

This paper studies the contraction property of time-varying differential-algebraic equation (DAE) systems by embedding them to higher-dimension ordinary differential equation (ODE) systems. The first result pertains to the equivalence of…

This letter presents the principles and techniques of active optical clock, a special laser combining the laser physics of one-atom laser, bad-cavity gas laser, super-cavity stabilized laser and optical atomic clock. As an example, a…

Local time is the measure of how much time a random walk has visited a given position. In multiple scattering media, where waves are diffuse, local time measures the sensitivity of the waves to the local medium's properties. Local…

We present in this work the calibration procedure and a performance study of long scintillator bars used for the time-of-flight (TOF) measurement in the HADES experiment. The digital front-end electronics installed at the TOF detector…

High precision fast photometry from ground-based observatories is a challenge due to intensity fluctuations (scintillation) produced by the Earth's atmosphere. Here we describe a method to reduce the effects of scintillation by a…

Large ground-based telescopes equipped with adaptive optics (AO) systems have ushered in a new era of high-resolution infrared photometry and astrometry. Relative astrometric accuracies of <0.2 mas have already been demonstrated from…

This article theoretically proposes a new dual interferometer technique to accurately calibrate two laser frequencies simultaneously using four-wave mixing in an alkali metal vapor cell. The two frequency-calibrated lasers are mixed to…

Wide Field Adaptive Optics (WFAO) systems represent the more sophisticated AO systems available today at large telescopes. A critical aspect for these WFAO systems in order to deliver an optimised performance is the knowledge of the…

Sets of short exposure, guided CCD frames are used to measure the noise added by the atmosphere to differential astrometric observations. Large nightly variations that are correlated with the seeing have been found in the data obtained over…

We describe the results of a search for time variability of the fine structure constant, alpha, using absorption systems in the spectra of distant quasars. Three large optical datasets and two 21cm/mm absorption systems provide four…

Adaptive optics (AO) systems and image reconstruction algorithms are indispensable tools when it comes to high-precision astrometry. In this paper, we analyze the potential of combining both techniques, i.e. by applying image reconstruction…

In this paper, we present an efficient numerical method to address a thermodynamically consistent gas flow model in porous media involving compressible gas and deformable rock. The accurate modeling of gas flow in porous media often poses…

Spectroscopic studies of massive and luminous O-type stellar atmospheres and winds have primarily been done by using 1D, spherically symmetric and stationary models. Both observations and modern theoretical models show that such stars have…