Johannes Sahlmann

My responsibilities within the James Webb Space Telescope project at STScI include:

• In-flight calibration of the focal plane geometric alignment, i.e. the determination of the locations of the instrument apertures relative to the guiding cameras. These calibrations are essential for efficient science operations of the observatory.
• Support early commissioning activities that involve astrometric measurements, e.g. telescope boresight corrections and alignment calibrations in support of the telescope’s attitude control system and of the guiding systems relative to the star trackers.
• In-flight determination and calibration of instrument geometric distortion.
• End-to-end simulations of the data analysis processes required for the above.
• Design and exercise rehearsal activities related to the above, including interfaces  with other Science Operations Centre (SOC) subsystems and the Mission Operations Centre (MOC).
• Coordination of two working groups.
• Preparation of astrometric reference catalogs.

Location of JWST instrument apertures projected onto the sky. Every blue dot is a Gaia source in the astrometric calibration field that can be leveraged for focal plane alignment. From Sahlmann et al. 2018.