Proposals submitted in response to this Special Call should preferably request no more than 25 hours of total execution time and should clearly indicate which of the criteria described above apply. Observing time will be allocated following recommendation by a committee of experts external to ESO. Due to the considerable amount of time already committed in Period 107 to Large Programmes and other high-priority programmes that could not be executed during Periods 105 and 106, only up to 15% of the time dedicated to science observations in Period 107 will be available through the Special Call. It is therefore expected that only very highly rated proposals may obtain observing time. Resubmissions of proposals rejected in previous semesters will not be accepted. The Director's Discretionary Time channel will remain open, but restricted to proposals targeting objects of a transient nature and not covered by an approved Target of Opportunity programme, requiring immediate observations of a sudden and unexpected astronomical event.

The submission of proposals in response to the Special Call can take place any time between 1 April and 1 September 2021. Further details on the procedures to be followed for the submission will be announced in the coming months.