Showing papers by "Dietrich Lemke published in 1994"
TL;DR: The Infrared Space Observatory (ISO) photometer is one of four instruments on board the European Space Agency ISO satellite scheduled for launch in September 1995 as mentioned in this paper, which covers the wavelength range 2.5 to 240 μm with wide and narrow spectral bands.
Abstract: The Infrared Space Observatory (ISO) photometer is one of four instruments on board the European Space Agency ISO satellite scheduled for launch in September 1995. It covers the wavelength range 2.5 to 240 μm with wide and narrow spectral bands. Diffraction-limited observations as well as wide-beam measurements of faint extended sources are possible. Polarimetric observations can be made over the whole wavelength range. The minimal detectable flux is ~10 mJy. The astronomical areas to be addressed range from solar system objects to cosmology.
19 citations
14 Sep 1994
TL;DR: In this article, annealing procedures for the PHT-S Si:Ga detectors were found to restore the photometric calibrations to within a few percent in the presence of high energy radiation.
Abstract: ISOPHOT, the photo-polarimeter on the Infrared Space Observatory (ISO) uses high sensitivity doped silicon and germanium photodetectors working in the wavelength range form 2.4 to 240 micrometers . Under low IR-background conditions such detectors show long and non-linear response relaxation to a step change of IR-illumination. We will show that this nonideal behavior can be described with high precision at least for the PHT-S Si:Ga detectors. In space, high- energy radiation will strongly influence the performance of the detectors operated a low temperature. Irradiation tests using a (gamma) -radiation source were performed on our Ge:Ga and stressed Ge:Ga detector simulating the radiation environment on the ISO orbit. We found annealing procedures for the detectors which restore the photometric calibrations to within a few percent.
11 citations
TL;DR: In this paper, a calibration facility simulating the optical and cryogenic environment of the Infrared Space Observatory (ISO) satellite has been built for characterizing the ISO photometer (ISOPHOT).
Abstract: A calibration facility simulating the optical and cryogenic environment of the Infrared Space Observatory (ISO) satellite has been built for characterizing the ISO photometer (ISOPHOT). This facility uses a commercially calibrated 900-K blackbody radiation source and optics at room temperature to provide an f /15 beam to the instrument, which is contained in a LHe cryostat. The low-level infrared flux levels of the ISO are obtained by using a light-sealed instrument chamber and cold attenuation filters. The infrared flux can be calculated using the known blackbody emission and the cold calibrated transmission spectra of the filters. The calibration facility further provides a scanning mechanism, a light modulator, and filters for polarization measurements and wavelength calibrations of the ISOPHOT spectrometer channels. Electrical support equipment for the instrument operation and software for data archiving and analysis have been customized for this project. The test program comprised a standardized acceptance test for the entire instrument and special tests addressing individual instrument properties. The data obtained contain the photometric sensitivities of ISOPHOT, optimized instrument settings, reference data for the integrated system tests, and inputs for the ongoing mission planning.
10 citations