The Use of a Standard Source of Synchrotron Radiation for Calibration of the Sensitivity of a Telescope with CCD Array and High Angular Resolution

Abstract

A method involving the use of a primary standard source of synchrotron radiation for precision calibration of the sensitivity of telescopes equipped with a CCD array and high angular resolution is considered. The method is based on precision reproduction of the spectral energy characteristics, the Gaussian distribution of the spectral density of the irradiance over a radiating region, and the stability and reproducibility of the characteristics of synchrotron radiation in a single-electron regime.Measurement of the metrological characteristics of a telescope equipped with a CCD array comprises the determination of the angular dependence of the absolute sensitivity in terms of units of the spectral density of irradiance, stability, reproducibility, sensitivity threshold, and dynamic range as well as estimation of the spectral and zonal correction of the sensitivity. A standard source of synchrotron radiation that supports reproduction and dissemination of spectro-radiometric quantities with the use of a single-electron regime of generation of synchrotron radiation and exhibits high stability and broad dynamic range amounting to 10 11 conforms the most thoroughly to this measurement problem.The Research Institute of Optophysical Measurements (VNIIOFI) has conducted metrological studies in conjunction with the Kurchatov Institute and PTB (Germany), correspondingly, on the Sibir-1, Sibir-2, and the MLS and Bessy II electron storage rings for the purpose of precision comparison of radiators with respect to the spectral density of irradiance and the spectral density of the radiant force by means of a telescope with cooled CCD array [1−3]. Precision calibration of such a telescope is critical both for comparison of the spatial distribution of the spectral density of irradiance of sources of radiation and in the determination of the angular dependence of the sensitivity of spaceborne telescopes and space vehicles designed for monitoring the Earth, upper atmosphere, and space vehicles.The absolute distribution of the spectral density of irradiance of synchrotron radiation from a radiating region obtained by means of Schwinger's theory, L(x, y) =Nγ 8 e 2 c 230R 3 Dσ x σ y (λ cr / λ) 4 [1+ (γΨ) 2 ] 2 ×