Search Publications
Transient Effects in ISOPHOT Data: Status of Modelling and Correction Procedures
Gabriel, C.; Acosta-Pulido, J. A.; Castañeda, H. O.
The calibration of ISOPHOT observations is hampered in many cases by the transient response of the detectors. Here we outline the behaviour observed in flight for the different ISOPHOT detectors. We also present some of the procedures which are currently used to correct transient effects and their implementation in the ISOPHOT Interactive Analysis.
ISO's Short Wavelength Spectrometer - Ultimate sensitivity. Reducing the effects of cosmic weather
Thi, W. F.; Valentijn, E. A.
Compared to the pre-launch measurements, the in-orbit noise levels of the Short Wavelength Spectrometer (SWS) detectors show a significant increase, considerably lowering the overall sensitivity. Cosmic ray impacts on the detectors and/or on the instrument electronics play an important role in the noise levels and consequently many observations of…
The Isocam Responsivity in Orbit. Standard star photometry
Altieri, B.; Blommaert, J. A. D. L.; Okumura, K. +5 more
An overview is given of the absolute flux calibration of the ISOCAM detectors. The flux calibration is based on observations of standard stars selected from the Ground Based Preparatory Programme, for which Kurucz stellar models are available. No dependencies of the responsivity on different configurations of the camera were found. No trend of cha…
The transient behaviour of the long wavelength channel of ISOCAM
Aussel, H.; Abergel, A.; Sauvage, M. +3 more
The detector of the long wavelength channel of the ISOCAM camera on-board the Infrared Space Observatory is a Gallium doped Silicon photo-conductor hybridized by Indium bump. It presents systematic memory effects of the response which can bias the photometry by a factor of typically 40%. The main features of the response after flux variations are …
The ISOCAM/LW Detector Dark Current Behaviour
Okumura, K.; Sauvage, M.; Biviano, A. +5 more
We describe the calibration, measurements and data reduction, of the dark current of the ISOCAM/LW detector. We point-out the existence of two significant drifts of the LW dark-current, one throughout the ISO mission, on a timescale of days, another within each single revolution, on a timescale of hours. We also show the existence of a dependence …
Space Operation and Performance of Doped Germanium Photo-Conducting Detectors in the Far Infrared: Experience from the ISO LWS
Griffin, Matt; Lim, Tanya; Swinyard, Bruce +3 more
The performance of the ten doped germanium photoconducting detectors on the Infrared Space Observatory Long Wavelength Spectrometer is discussed. This instrument was designed to make spectroscopic measurements of astronomical sources in the wavelength range from 43 to 198 µm. It employed^* a combination of stressed and unstressed Ge:Ga detec…
The ISO-SWS detectors: Performance trends and space radiation effects
Heras, A. M.; Morris, P.; Feuchtgruber, H. +6 more
We present a trend analysis of the ISO-SWS detector performance and a study of the space radiation effects on the SWS detectors. In particular, dark currents, dark current noise and detector responses have been checked as a function of time through the mission and as a function of time in a revolution. The results show that these parameters were s…
Modelling Transient Effects in the IR Array of the Short Wavelength Channel of ISOCAM
Rouan, D.; Epstein, G.; Tiphène, D. +1 more
The short-wave channel (SW) of ISOCAM, the IR camera on board the ISO satellite, is equipped with a 32 × 32 CID InSb array. This array shares with other detectors of ISO instruments the characteristic of being subject to some time lag when responding to a flux variation. Known as transient effect, this default which is not quite understood (in par…
Glitch effects in ISOCAM Long Wave detector
Starck, J. -L.; Claret, A.; Dzitko, H. +1 more
One of the main limitations to the sensitivity of observations carried out with the ISOCAM infrared camera comes from the responsivity variations and glitches caused by impacts of charged particles. After more than 28 months of successful operations, the predicted glitch rate has been re-evaluated and compared to in-flight measurements. Glitch pro…
Deglitching methods by the ISOPHOT Interactive Analysis (PIA)
Gabriel, C.; Acosta-Pulido, J. A.
The ISOPHOT detectors were continuously exposed to high energy cosmic particles hits, resulting in an average hit rate frequency of an event per every 7 s. The net effect is a disturbance of the readout voltages, which decreases the signal-to-noise ratio and hence the photometric accuracy level. Thanks to the highly redundant readout method of ISO…