Boresight calibration of FIFI-LS: In theory, in the lab and on sky

Sebastian Colditz, Randolf Klein, Simon Beckmann, Aaron Bryant, Christian Fischer, Fabio Fumi, Norbert Geis, Rainer Hönle, Alfred Krabbe, Leslie W. Looney, Albrecht Poglitsch, Walfried Raab, Sarah E. Ragan, Felix Rebell, Maureen L. Savage

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The Field-Imaging Far-Infrared Line-Spectrometer (FIFI-LS) entered service on the Stratospheric Observatory for Infrared Astronomy (SOFIA) on March 2014. Exact pointing of the instrument is important. The SOFIA telescope provides an absolute pointing stability of 1" rms, which is sufficient for FIFI-LS. The instrument boresight relative to the telescope reference system is established with accuracy better than 1". FIFI-LS has a built-in rotating K-Mirror to derotate the instrument field of view. Perfect alignment of the optical axis of the K-Mirror and the optical axis of the optical systems in both instrument channels is practically impossible. The remaining offsets result in a dependence of the instrument boresight on the K-Mirror position. Therefore a boresight calibration model is established for each channel. With these models the instrument boresight is calculated and transferred to the telescope control software. Achieving precise calibration of the boresight has been an ongoing process including the first optical models of the instrument, measurements in different laboratories and finally measurements during the commissioning flight series. In this paper, the approach used to calibrate FIFI-LS's boresight is explained. This includes the model used and an overview of the laboratory, as well as the in-flight measurements leading to the calibrated boresight model.

Original languageEnglish (US)
Title of host publicationGround-Based and Airborne Instrumentation for Astronomy V
EditorsSuzanne K. Ramsay, Ian S. McLean, Hideki Takami
ISBN (Electronic)9780819496157
StatePublished - 2014
EventGround-Based and Airborne Instrumentation for Astronomy V - Montreal, Canada
Duration: Jun 22 2014Jun 26 2014

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherGround-Based and Airborne Instrumentation for Astronomy V


  • Far-infrared
  • Image Rotator
  • Integral Field Spectroscopy
  • Spectrometer

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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