In solar observations, when the lifetime of your target structure is long (> a few days, like a sunspot), your observation will only be carried out if your target structure is present on the Sun. If your proposal is ranked as Grade A and your target structure does not appear during the solar campaign of the current cycle, your observation will be carried over to the next cycle.
On the other hand, if your target is a short-lived or dynamic phenomenon, your observation is carried out following the schedule created by ALMA observatory staff based on requests from PIs. If the obtained data pass quality assurance, the data are provided to you and your project ends, even if your target structure is not present during the observation. Note: You cannot select any targets that are not written as the targets in your proposal.