Spectrophotometry of Stars in the Near Infrared

Abstract

The aim of this exercise is to become acquainted with some aspects of spectro-photometrical observations in the near infrared with modern detectors and mainly with the calibration problem. Any spectrophotometrical work i.e. any attempt to derive the spectral energy distribution of a star includes the determination of the response curve of the system, S(λ), i.e. of the relation between the flux of the star, F(λ), and the signal read at the output of the detector, D(λ) D(λ) = S(λ)F(λ). The shape of the function S(λ) is the result of the variations with wavelength λ of the transmissivity of the lenses, the reflectivity of the mirrors and the efficiency of the grating as well as of the variation with λ of the quantum efficiency of the detector.