Voyager data

From Tauwiki

[edit] Instrument

The Voyager 1 and 2 Ultraviolet Spectrometers are nearly identical instruments. This discussion applies to both, except in a few instances in which important differences between the two are noted explicitly. The Voyager 1 Ultraviolet Spectrometer (UVS) is a compact Wadsworth mounted objective grating spectrometer that covers the wavelength range of 0.0535 to 0.1702 micron (0.0513 to 0.1680 micron for the Voyager 2 UVS). It records the entire spectrum within this range in a single exposure.

[edit] Calibration

Flat-field correction

A Fixed Noise Pattern (FPN) is used to correct for the channel to channel variation.

Background subtraction

In interplanetary space, detector dark counts arise mainly from effects of gamma radiation from the radioisotope thermoelectric generators (RTG) that power the spacecraft. The count rate is about 0.02 counts per channel per second

Descattering

Light scattered within the instrument illuminates channels outside the ideal transmission function of the collimator. The effects of scattering are removed by a process called descattering. Descattering is accomplished through the use of a matrix operator, a 126x126 element matrix which describes the response of detector channel 'j' to the measured signal at channel 'i'. This scattering matrix is completely empirical, having been determined from laboratory measurements of 50 individual emission lines covering the entire passband.