In or to perform the geometric correction, the chris-box needs telemetry files. They are publicly available on an ESA/REDU archive server: http://194.78.233.110/products/data/CHRIS_Additional_data/
The archive provides individual files for the most recent acquisitions, older files are bundled in compressed files.
To find the corresponding telemetry files for a given acquisition follow these steps:
Get [Target Name] and [Date] from image meta data; the dashes '-' in the date must be removed (e.g. for image CHRIS_MB_080501_9BE1_41 meta data [Target Name]=Manly-Beach and [Date]=20080501 removing the '-' from the meta data date value '2008-05-01')
Connect to the telemetry archive
Use a filter *.[Target Name]_?????_CHRIS_center_times_[Date]_* to locate the Image Center Times file (e.g. it would find: Pass9301.Manly-Beach_39905_CHRIS_center_times_20080501_65534)
????? should match a five-digit string to be used as reference [Ref] (e.g. in this case it would be [Ref]=39905)
Use a filter CHRIS_[Ref]_*.tar.gz to locate the compressed GPS file (e.g. it would find: CHRIS_39905_39909.tar.gz)
Extract from the gzip archive the file: CHRIS_[Ref]_*_PROBA1_GPS_Data, where PROBA's GPS position and velocity data are recorded. There also is a second file PPU_UPLOAD_*, which can be ignored (e.g. extract CHRIS_39905_39909_PROBA1_GPS_Data)
A pre-packaged archive is available for download from Archive_CHRIS_Telemetry_Data_20201028.zip. It has been packed on the 28th of October 2020