What is the ruling on one who masturbated knowing that Fajr Adhan was near in Ramadan, until the Adhan was called and he ejaculated; has his fast been invalidated, and is he required to make up for it and offer expiation?

Masturbation is forbidden, and its prohibition intensifies in Ramadan. It invalidates the fast if it leads to ejaculation after dawn. One must repent from this act and from intentionally invalidating the fast. It is obligatory to make up for the day without expiation.