Thanks for the note, " 63 periods of 30 days are 1890 days and correspond to 64 lunations, as found above. One lunation, calculated that way, lasts 29 days 12 hours 45 minutes, exact value 29 d 12 h 44 m 2.9 s (average from 1989 AD), mistake less than one minute per lunation, or half a day in a lifetime.
Mayans were more accurate by selecting a 405-lunar standard based on 18980 days, accurate to withing 2 hours in 30 and 29 red and back moons marked an important 52 year cycle. Of course Mayans calculation longer periods by considering other adjustments, issues that can be discussed after Bruce and I digest Harvey and Victoria Bricker's 2011 900 page book. Bruce is 300 pages into the book, well ahead of me.