The calibration and cross-calibration of the Herschel instruments is the responsibility of the observatory, in particular of the ICCs and the HSC. The pointing calibration is the responsibility of the HSC and the MOC. Therefore, the preparation and scheduling of calibration observations is an exclusive duty of these groups. The calibration data required for the reduction and analysis of the Herschel observations will be provided to the astronomer in the form of products in the Herschel Science Archive, and is integrated in the Data Processing software.

Calibration and engineering observations were the main components of the schedule during the Commissioning and Performance Verification phases. Their aim was to achieve the necessary understanding of the instruments and spacecraft, and attain the required calibration and pointing accuracies to ensure a proper execution and data reduction of the science observations during the Science Demonstration and Routine phases. In the routine phase, it is expected that up to 15% of the available observatory time will be used for calibration. Calibration observations may be based on non-AOT observing modes defined by the instrument specialists at the ICCs and HSC, but in general they will be defined using the AOTs available to the community for science observations. Calibration observations are in principle public. However, if a calibration observation is a duplicate of a scientific observation (see the "Herschel Space Observatory Call for Proposals: Policies and Procedures" document for a definition of "duplication"), the corresponding proprietary rights will apply.