Phased observations are needed for a variety of purposes.  The most complicated one is the case of an eclipsing binary or an explanetary transit, shown here.

The times of the periodic phenomena are assumed to be given by an initial time, T0, a period P0, and an event number E such that the reference time of the event is given by t0 = T0+E*P0.  This could be the time of mid-eclipse/mid-transit, for instance.

One presumedly wants to start some time before the event and cover the object either for a given amount of time or until the measurement is symmetric around the reference time.  The MONET/Central portal captures this constraint in terms of the following:

  • there is some important "event" (e.g. eclipse or transit) which lasts some amount of time, called the "Duration";
  • one presumedly wants some data sometime before the start of the "event";
  • the earliest time before and the latest time before the start of the "event" defines the window in time when the MONET scheduler should start your observations;
  • if you simply give a certain number of exposures, the end of the sequence happens when all exposures have been made;
  • if you want to end the sequence after some unknown number of exposures corresponding to the same amount of time started before t0, you can select the "Automatically end periodic observations" in the "Setup" panel of the Observation inspector: