Procedures have been established and are in place to allow for post-call modifications if proposers consider there is a need to modify and refine approved observations after the call has been closed. They are intended to allow some flexibility with respect to changes that are oriented to maximise the scientific return of the mission. However, they will be restricted to the minimum, the have to be requested through Helpdesk, they will be reviewed by the HSC Community Support Group and may have to be finally approved by the Project Scientist.

The modifications made shall not alter the scientific content or intent of the original AOR and must be such that the programme stays within the originally allocated observing time. Major modifications will need to be reviewed and approved by the Project Scientist, in consultation with the HOTAC Chair if necessary.