Due to the constraints introduced by the LECS and by the attitude system, the observing efficiency within the requested time window may be substantially below the optimum value. The level at which these observations will be feasible remains to be assessed after the gyro-less mode is operational. The project reserves the right not to perform an observation in case the efficiency is less than .
For the fifth year of operations not more than 7% of the program will be allocated to time-constrained (e.g. coordinated, phase-dependant) observations.