Target Selection and Scheduling for the Terra Hunting Experiment

The Terra-Hunting experiment aims to carry out a radial velocity search for Earth twins; Earth-mass planets in Earth-like orbits around solar-type stars. To carry out this experiment are building HARPS-3, an improved copy of the earlier HARPS spectrographs, to be installed on the Isaac Newton Telescope, which we will upgrade to operate in unattended robotic mode.   The experiment will share the telescope with a selection of "open time" programmes and both will be scheduled in real-time with an automatic scheduler.  We discuss the target selection and scheduling for the Terra-Hunting experiment, and the interaction between the two. We demonstrate how the preference for stars with long observing seasons affects the scheduling and target selection, and how this is complicated by the requirements of open time proposals which are likely to be time critical in order to capitalise on the unique flexibility of HARPS-3.  We also show how the Gaia DR2 distances can be used to test prospective targets for both binarity and main-sequence evolution. 

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