The total (or chargeable) observing time per observing block is calculated by adding all science exposure times and the detector readout times between them, plus a set 120 seconds for telescope slew and acquisition (the final detector readout is done as the telescope slews). Use the HARPS3 Exposure Time Calculator for the total science exposure time. A group is a set of blocks for the same target, with the blocks being carried out at different times. If more than one block is required, enter how many.