The spectral photon flux of the radiometric calibration spectral source for the NIRSpec instrument of the James Webb Space Telescope

摘要

The radiometric calibration spectral source (RCSS) is a very low photon flux radiation source based on an integrating sphere, operated under vacuum and cryogenic conditions, for the testing and calibration of the near infrared multiobject dispersive spectrograph (NIRSpec). NIRSpec itself is a part of the scientific instrumentation of the James Webb Space Telescope. For the traceable calibration of the photon flux emitted by the RCSS in the wavelength range from 0.7 (mu)m to 5 (mu)m, dedicated calibration schemes were developed at PTB. To achieve this goal, the Spectral Radiance Comparator Facility and the Reduced Background Calibration Facility of the PTB have been significantly improved with respect to their detector instrumentation.