Once at the observatory, you will receive support from an astronomer, of the Paranal Science Operations (PSO) team, to prepare your observations; but we can be contacted anytime beforehand to answer any pending question through the ESO Operations Helpdesk.

PSO has prepared OBs for most of the setup necessary for photometric standards calibrations. They can be used at any time for a visitor run and if needed can be modified online (at the console).

Calibrations of the data taken over night are done automatically on the next morning. The completeness and quality of these calibrations are checked by your daytime support astronomer. Only special request OBs need to be prepared by yourself.
Weather permitting PSO will take twilight sky flats and other specific observations according to the Calibration Plan. Since it is a slow process to get a full set of possible filters/cameras combinations, it is important for us to know upon your arrival the list of settings you will be using.

All required information about visitor mode observations runs can be found in the pages of Paranal Science Operations under VA info.