Related papers: How achromatic is the stellar scintillation on lar…
We investigate the effects of atmospheric dispersion on observations of the Sun at the ever-higher spatial resolutions afforded by increased apertures and improved techniques. The problems induced by atmospheric refraction are particularly…
The spectroscopic and photometric analysis of sample Am stars are carried out to determine the stellar characteristics of each studied star. The CCD photometric analysis of HD 98851 and HD 207561 show clear evidence of pulsation variability…
Imaging through scattering and random media is an outstanding problem that to date has been tackled by either measuring the medium transmission matrix or exploiting linear correlations in the transmitted speckle patterns. However,…
Fluctuating atmospheric emission is a dominant source of noise for ground-based millimeter-wave observations of the CMB temperature anisotropy at angular scales $\gtrsim 0.5^{\circ}$. We present a model of the atmosphere as a discrete set…
A defocused image of a bright single star in a small telescope contains rich information on the optical turbulence, i.e. the seeing. The concept of a novel turbulence monitor based on recording sequences of ring-like intrafocal images and…
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…
Spectral energy distributions for models of arbitrarily rotating stars are computed using two dimensional rotating stellar models, NLTE plane parallel model atmospheres, and a code to integrate the appropriately weighted intensities over…
The properties of galaxies in the local universe have been shown to depend upon their environment. Future large scale photometric surveys such as DES and Euclid will be vital to gain insight into the evolution of galaxy properties and the…
How important is an independent diameter measurement for the determination of stellar parameters of solar-type stars? When coupled with seismic observables, how well can we determine the stellar mass? If we can determine the radius of the…
Clumping in the winds of massive stars may significantly reduce empirical mass-loss rates, and which in turn may have a large impact on our understanding of massive star evolution. Here, we investigate wind-clumping through the linear…
We present a fitting function to describe the statistics of flux modulations caused by interstellar scintillation. The function models a very general quantity: the cross-correlation of the flux observed from a compact radio source of finite…
The dynamic and secondary spectra of many pulsars show evidence for long-lived, aligned images of the pulsar that are stationary on a thin scattering sheet. One explanation for this phenomenon considers the effects of wave crests along…
We propose an experiment using a conventional optical telescope to determine whether aberration of starlight results from special relativistic effects external to a measurement sensor or from optical effects within a sensor. The proposed…
The aureoles around stars caused by thin cirrus limit nighttime measurement opportunities for ground-based astronomy but can provide information on high-altitude ice crystals for climate research. In this paper we attempt to demonstrate…
Cosmology with large interferometric telescopes is a rich and largely unexplored subject, involving three types of measurement: astrometric measurement of absolute distances and proper motions, dispersions of relative proper motions, and…
We have made high-resolution, high-sensitivity dynamic spectra of a sample of strong pulsars at 430 MHz with the Arecibo radiotelescope. For 4 pulsars we find faint but sharply delineated features in the secondary spectra. These are…
We have performed a 5-colour surface photometric study of the high-galactic-latitude area of dark nebula LDN 1642. Scattered light properties are presented of diffuse, translucent and opaque dust over the range of 3500 -- 5500 A. Far…
Astronomers usually need the highest angular resolution possible, but the blurring effect of diffraction imposes a fundamental limit on the image quality from any single telescope. Interferometry allows light collected at widely-separated…
We study the fundamental limits of detection for astrophysical observations in the far infrared. Understanding these fundamental limits is critical to the planning and analysis of experiments in this region. We specifically characterize the…
The paper contains the review of a number of wide-angle polarization CCD-measurements of the twilight sky in V and R color bands with effective wavelengths equal to 550 and 700 nm. The basic factors effecting (usually decreasing) on the…