Sawai Jai Singh the statesman astronomer of 18th century India designed astronomical instruments of masonry and stone, built observatories prepared a Zij or a text for astronomical calculations and sent a fact-finding scientific mission to Europe. His high precision instruments were designed to measure time and angles to the very limit of naked eye observing.

An invaluable resource for working programmers, as well as a fount of useful algorithmic tools for computer scientists, astronomers, and other calendar enthusiasts, The Ultimate Edition updates and expands the previous edition to achieve more accurate results and present new calendar variants. The book now includes coverage of Unix dates, Italian time, the Akan, Icelandic, Saudi Arabian Umm al-Qura, and Babylonian calendars. There are also expanded treatments of the observational Islamic and Hebrew calendars and brief discussions of the Samaritan and Nepalese calendars. Several of the astronomical functions have been rewritten to produce more accurate results and to include calculations of moonrise and moonset. The authors frame the calendars of the world in a completely algorithmic form, allowing easy conversion among these calendars and the determination of secular and religious holidays. LISP code for all the algorithms is available in machine-readable form.

Expanded coverage includes generic cyclical calendars, astronomical lunar calendars, and the Korean, Vietnamese, Aztec, and Tibetan calendars.

Skywatchers of Ancient Mexico helped establish the field of archaeoastronomy, and it remains the standard introduction to this subject. Combining basic astronomy with archaeological and ethnological data, it presented a readable and entertaining synthesis of all that was known of ancient astronomy in the western hemisphere as of 1980. In this revised edition, Anthony Aveni draws on his own and others' discoveries of the past twenty years to bring the Skywatchers story up to the present. He offers new data and interpretations in many areas, including: The study of Mesoamerican time and calendrical systems and their unprecedented continuity in contemporary Mesoamerican culture The connections between Precolumbian religion, astrology, and scientific, quantitative astronomy The relationship between Highland Mexico and the world of the Maya and the state of Pan-American scientific practices The use of personal computer software for computing astronomical data With this updated information, Skywatchers will serve a new generation of general and scholarly readers and will be useful in courses on archaeoastronomy, astronomy, history of astronomy, history of science, anthropology, archaeology, and world religions.