Search results for "SCOPE"
showing 10 items of 2420 documents
Multiband RadioAstron space VLBI imaging of the jet in quasar S5 0836+710
2019
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.-- Open Access funding provided by Max Planck Society.
Detection of Intrinsic Source Structure at ~3 Schwarzschild Radii with Millimeter-VLBI Observations of SAGITTARIUS A*
2018
We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A*, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional {\it uv} coverage in the N-S direction, and leads to a spatial resolution of $\sim$30 $\mu$as ($\sim$3 Schwarzschild radii) for Sgr A*. The source is detected even at the longest baselines with visibility amplitudes of $\sim$4-13% of the total flux density. We argue th…
Relativistic beaming and gamma-ray brightness of blazars
2009
We investigate the dependence of gamma-ray brightness of blazars on intrinsic properties of their parsec-scale radio jets and the implication for relativistic beaming. By combining apparent jet speeds derived from high-resolution VLBA images from the MOJAVE program with millimetre-wavelength flux density monitoring data from Metsahovi Radio Observatory, we estimate the jet Doppler factors, Lorentz factors, and viewing angles for a sample of 62 blazars. We study the trends in these quantities between the sources which were detected in gamma-rays by the Fermi Large Area Telescope (LAT) during its first three months of science operations and those which were not detected. The LAT-detected blaz…
Determination of particle number and brightness using a laser scanning confocal microscope operating in the analog mode
2008
We describe a method to obtain the brightness and number of molecules at each pixel of an image stack obtained with a laser scanning microscope. The method is based on intensity fluctuations due to the diffusion of molecules in a pixel. For a detector operating in the analog mode, the variance must be proportional to the intensity. Once this constant has been calibrated, we use the ratio between the variance and the intensity to derive the particle brightness. Then, from the ratio of the intensity to the brightness we obtain the average number of particles in the pixel. We show that the method works with molecules in solution and that the results are comparable to those obtained with fluctu…
BALDONE 1.2M TELESCOPE PLATE ARCHIVE - HIDDEN RESERVES OF THE FON PROJECT
2018
The plate archive of the 1.2 m Baldone telescope (Latvia) has approximately 780 and 4660 astronegatives exposed in 1967-1993 in the U (ZU21 + UG1 filter plates) and V (A600N + ZS17 filter films) closed to Johnson system U and V passbands. Digitization of astronegatives is carried out using the Epson Expression 10000XL scanner, the scanning mode is 1200 or 2400 dpi, each field covers 19 square degrees of sky. The plates and films are scanned at the Baldone Observatory, processing of digitized scans is carried out by the observers in Baldone, at the Research Institute "Mykolaiv Astronomical Observatory" and at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. …
UV-PHOTOMETRY WITH THE 1.2 M SCHMIDT TELESCOPE IN BALDONE
2016
TheUniversityofLatvia's Institute of astronomy possesses a collection of 22 thousand photographic plates taken by the1.2 mSchmidt telescope located at the Baldone observatory. Among others, there are 767 astronegatives in this collection obtained in 314 sky areas using the Johnson U-filter. The field of view of each negative covers 19 square degrees. The plate scale is 72”/mm. The digitizing of the UV-collection has started in June 2016 with EPSON EXPRESSION 10000XL flatbed scanner. The general aim of the digitizing is to obtain UV-magnitudes and positions of all objects registered on the plates. Up to date near a half of the UV-collection is digitized. 24 digitized MEGA program plates of t…
Giant Dzyaloshinskii-Moriya Interaction and Room-Temperature Nanoscale Skyrmions in CoFeB/MgO Heterostructures
2021
Magnetic skyrmions in heavy metal (HM)/CoFeB/MgO structures are of particular interest for skyrmion-based magnetic tunnel junction (MTJ) devices because of their reliable generation, stability and read-out through purely electrical methods. To optimize the properties, such as stability, a strong Dzyaloshinskii-Moriya interaction (DMI) is required at room temperature. Here, using first-principles calculations, we demonstrate that giant DMI can be obtained in Ir/CoFe structures with an Fe-terminated configuration. Moreover, Brillouin light scattering measurements show that indeed Ta/Ir/Co20Fe60B20/MgO thin films with perpendicular magnetic anisotropy exhibit a large DMI value (1.13 mJ/m2), wh…
Scanning electron microscopy characterization of ZnSe single crystals grown by solid-phase recrystallization
2000
ZnSe single crystals were grown from n-type microcrystalline boules by a Solid Phase Recrystallization (SPR) method. The recrystallizations were performed under different atmospheres, Ar or Se, and pressures to investigate the influence of growth conditions on the structural features of the resulting crystals. The samples were mechanically and mechano-chemically polished in a bromine methanol solution and, then, etched in HCl for a short time, before characterization. The homogeneity and the nature of defects in the crystals were studied by Cathodoluminescence (CL) in the scanning electron microscope (SEM). CL measurements show the existence of slip bands in the recrystallized samples, like…
MILES extended: Stellar population synthesis models from the optical to the infrared
2016
We present the first single-burst stellar population models which covers the optical and the infrared wavelength range between 3500 and 50000 Angstrom and which are exclusively based on empirical stellar spectra. To obtain these joint models, we combined the extended MILES models in the optical with our new infrared models that are based on the IRTF (Infrared Telescope Facility) library. The latter are available only for a limited range in terms of both age and metallicity. Our combined single-burst stellar population models were calculated for ages larger than 1 Gyr, for metallicities between [Fe/H] = -0.40 and 0.26, for initial mass functions of various types and slopes, and on the basis …
Development of a 3D CZT detector prototype for Laue Lens telescope
2010
We report on the development of a 3D position sensitive prototype suitable as focal plane detector for Laue lens telescope. The basic sensitive unit is a drift strip detector based on a CZT crystal, (similar to 19x8 mm(2) area, 2.4 mm thick), irradiated transversally to the electric field direction. The anode side is segmented in 64 strips, that divide the crystal in 8 independent sensor (pixel), each composed by one collecting strip and 7 (one in common) adjacent drift strips. The drift strips are biased by a voltage divider, whereas the anode strips are held at ground. Furthermore, the cathode is divided in 4 horizontal strips for the reconstruction of the third interaction position coord…