Geometric calibration of Colour and Stereo Surface Imaging System of ESA's Trace Gas Orbiter
This addresses a niche problem for space telescope calibration in planetary science, but it is incremental as it adapts existing principles to a specific instrument.
The authors tackled the problem of geometric calibration for telescopes with large focal lengths and complex off-axis optics, which lacks specialized methods, by developing a general calibration method for the CaSSIS telescope on ESA's Trace Gas Orbiter, making the code and data available online.
There are many geometric calibration methods for "standard" cameras. These methods, however, cannot be used for the calibration of telescopes with large focal lengths and complex off-axis optics. Moreover, specialized calibration methods for the telescopes are scarce in literature. We describe the calibration method that we developed for the Colour and Stereo Surface Imaging System (CaSSIS) telescope, on board of the ExoMars Trace Gas Orbiter (TGO). Although our method is described in the context of CaSSIS, with camera-specific experiments, it is general and can be applied to other telescopes. We further encourage re-use of the proposed method by making our calibration code and data available on-line.