Sunrise / Sunset / Twilight times for the Portuguese aerodromes can be obtained from the following website:
The tables provided have been prepared by the Faculty of Sciences of the University of Lisbon.
The times given for the sunrise (SR) and sunset (SS) are calculated taking into account the sun’s equatorial coordinates on that day and moment as well as it’s distance from the Earth. It takes into account atmospheric refraction. The moments thus calculated correspond to the instant the sun’s upper limb touches the local horizon defined by the aerodrome elevation (in meters), with respect to ARP.
The times in the tables are given in UTC for beginning of civil morning twilight (TWILIGHT FROM), sunrise (SR) sunset (SS), and end of civil evening twilight (TWILIGHT TO), for the civilian year.
The UTC times given for the beginning of civil morning twilight and end of civil evening twilight are calculated for the solar disk’s centre at an altitude of 6° below the horizon, as commonly used.