In this paper, we present the results of characterizing the properties of the Moravian Instruments G4‐16000 CCD cameras, based on the Kodak KAF‐16803 chip. Such cameras are widely used in several ...robotic telescope projects, as well as by amateurs. We demonstrate both large light response nonlinearity (up to tens of percents) and significant bias level instability of these cameras, and outline possible ways of overcoming these problems.
Abstract
A promising energy range to look for angular correlations between cosmic rays of extragalactic origin and their sources is at the highest energies, above a few tens of EeV (1 EeV ≡ 10
18
...eV). Despite the flux of these particles being extremely low, the area of ∼3000 km
2
covered at the Pierre Auger Observatory, and the 17 yr data-taking period of the
Phase
1
of its operations, have enabled us to measure the arrival directions of more than 2600 ultra-high-energy cosmic rays above 32 EeV. We publish this data set, the largest available at such energies from an integrated exposure of 122,000 km
2
sr yr, and search it for anisotropies over the 3.4
π
steradians covered with the Observatory. Evidence for a deviation in excess of isotropy at intermediate angular scales, with ∼15° Gaussian spread or ∼25° top-hat radius, is obtained at the 4
σ
significance level for cosmic-ray energies above ∼40 EeV.
Study of CO adsorption on Sn/Rh(1 1 1) Hanyš, P.; Janeček, P.; Šutara, F. ...
Surface science,
09/2007, Letnik:
601, Številka:
18
Journal Article, Conference Proceeding
Recenzirano
An ultra thin Sn layer (6
Å) was deposited onto Rh(1
1
1) single crystal surface. We followed changes in low energy electron diffraction (LEED) pattern during progressive annealing together with ...development of CO adsorption capacity and photoelectron spectra obtained using synchrotron radiation. Surface bimetallic alloy development with increasing temperature was followed by LEED and synchrotron radiation photoelectron spectroscopy (SRPES). LEED results show several surface structure of Sn/Rh(1
1
1) sample in dependence on sample temperature. If it increases, the surface structure develops to the stable ordered (√3
×
√3)
R30° structure. Surface CO adsorption depends strongly on the amount of Sn in the top sample layer then it corresponds to the development of the surface structure. The CO adsorption capacity raises with increasing temperature.
Photoelectron spectra of Sn and Rh core levels and their shifts and shapes were studied during the annealing and CO adsorption. The resulting spectra are used to discuss the Sn–Rh surface alloy creation.
The goal of this paper is to demonstrate the CO adsorption on the Sn/Rh(1
1
1) surface. Valence band spectra measured at different primary energies are presented to demonstrate this effect. These spectra show different adsorption properties of the studied system in dependence on the amount of Sn in the top layer and geometric structure of the surface.
We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is ...observed, confirming the presence of the so-called
second-knee
feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays.
FRAM for CTA Janeček, P.; Prouza, M.; Ebr, J.
EPJ Web of Conferences,
01/2015, Letnik:
89
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The Cherenkov Telescope Array (CTA) is a project to build a new generation ground-based gamma-ray observatory. Among other goals, the project aims to achieve high precision of gamma-ray energy ...measurement while maximizing the use of observation time. These objectives require detailed and fast information about atmospheric conditions, particularly the transparency which includes cloudiness (including thin high-altitude clouds) and aerosol content. This knowledge is required not only to select and calibrate data after observation, but also to make on-the-fly scheduling decisions. To provide such data without interfering with the observation (as would be the case when using laser-based methods), we propose to use the “FRAM” (F(/Ph)otometric Robotic Atmospheric Monitor) device, which is a small robotic astronomical telescope with a large field of view and a sensitive CCD camera. FRAM will use stellar photometry to measure atmospheric extinction across the field of view of the CTA. The fast robotic mount of the telescope allows quick observation of multiple fields when the array is split and even a check of the conditions in the directions of the upcoming observations. The FRAM concept is built upon experience gained with a similar device operated at the Pierre Auger Observatory.
PDF
