Abstract
Most extrasolar planets have been detected by high resolution spectroscopy or in a few cases transits acoross the stellar disk. I will report a work where a planet V391 Peg b, has been detected by a different method: The study of variations in the light travel time of pulsations of the star. The star is a subdwarf B star, and has evolved through a giant phase where a large fraction of its atmosphere has been lost. It was discovered as a fairly steady pulsator in 1999 when Roy Østensen and myself tested a new observing techinique at the Nordic Optical Telescope at La Palma. An international team of observers have for 7 years observed the star frequently and detected a pulse arrival time variation with amplitude 5 seconds and a period of 3.2 years which is interpreted as the orbital period of a planet. How we managed to introduce this observing technique at the Nordic Optical Telescope is a long story, which started at the Skibotn Observatory in Northern Norway.