The data processing pipelines for the Herschel/SPIRE imaging Fourier transform spectrometer

Abstract

We present an update to the data processing pipelines that generate calibrated spectral data products from the Spectral and Photometric Imaging Receiver (SPIRE), one of three scientific instruments onboard the European Space Agency's Herschel Space Observatory launched on 14 May 2009. The pipelines process telemetry from SPIRE's imaging Fourier Transform Spectrometer (FTS) taken in point source, jiggle- and raster-map observing modes, producing calibrated spectra in low-, medium-, high-, and mixed low- and high-spectral resolution. While the order and algorithms of the data processing modules in the spectrometer pipelines remain for the most part unchanged compared to their pre-launch status, some improvements and optimizations have been realized through the analysis of data from the performance verification and science demonstration phases of the mission. The data processing pipelines for the SPIRE FTS as of the beginning of the routine phase of the Herschel mission are presented in their entirety, with more detailed descriptions reserved for those elements that have changed since launch, in particular the first- and second-level correction steps for glitches, the step that corrects for clipped samples, and the process by which Level-1 spectral data are converted to Level-2 products. In addition, we discuss some of the challenging aspects still faced by the automated processing pipelines, such as the removal of the contributions from the Herschel telescope and SPIRE instrument, and the relative spectral response correction and flux conversion steps.