Maximum possible observation time for an antenna which can track the Sun from sun-rise to sun-set. This plot is based on the current number of instruments which have provided observation data today. If the antenna is just pointing to zenith, then observation time will be drastically reduced. This plot changes during the year and it will automatically be updated every day at 22:00UT. Those observers who use the automatic scheduler tool can ignore this plot, the tool automatically adjusts observation time every day. But those who don't use automatic scheduler may adjust observaton time in the text-file 'scheduler.cfg' in the application folder of Callisto.