Petrus Gaszowiec probably began his education at the local school in Strzelce Opolskie and subsequently entered the Kraków Academy in the winter semester of 1446.
Among other texts, he wrote Computus nouus totus fere Astronomie fundametum pulcerrimum contines and constructed numerous astronomical tables.
The Almanach Cracoviense ad annum 1474, which is the oldest surviving document printed on Polish soil, was most likely written by Gaszowiec.
Similar to other calendars and almanacs of the era, the Almanach Cracoviense lists church holy days alongside astronomical data.
The book, which was likely written by the Arabic author al-Majriti, discusses such topics as the nature of the sky and atmospheric phenomena, the connections between the signs of the zodiac and the planets, as well as the summoning of ghosts.