Short answers, pulled from the story.
Daniel Heartz was an American musicologist born on the 5th of October 1928 and died on the 24th of November 2019. He was a professor of music at the University of California, Berkeley, and specialized in European music from the Renaissance through the early nineteenth century, with particular focus on opera, the galant style, and the Viennese classical school.
Heartz wrote several major works including Mozart's Operas (University of California Press, 1990), Music in European Capitals: The Galant Style, 1720-1780 (W. W. Norton, 2003), Haydn, Mozart and the Viennese School, 1740-1780 (W. W. Norton, 1995), and Mozart, Haydn and Early Beethoven, 1781-1802 (W. W. Norton, 2008). His earliest monograph was Pierre Attaingnant: Royal Printer of Music, published in 1969.
Daniel Heartz received Guggenheim Fellowships, ASCAP-Deems Taylor Awards for writing about music, and the Kinkeldey Award from the American Musicological Society, which is the society's highest recognition for a published book.
Heartz studied at Harvard University and spent his teaching career as a professor of music at the University of California, Berkeley, where he also lived. Two of his major books were published by the University of California Press.
Pierre Attaingnant: Royal Printer of Music, published by the University of California Press in 1969, examined Attaingnant's role as one of the earliest printers to apply movable type to polyphonic music in sixteenth-century France. Attaingnant held an official royal designation from the French crown, making him a central figure in the circulation of printed music in Renaissance Paris.
Heartz edited Mozart's opera Idomeneo for the Neue Ausgabe samtlicher Werke, published in Kassel in 1972. This critical edition required adjudicating between manuscript variants and understanding the performance conditions of the Munich court theater for which Mozart originally composed the work.