Neil F. Michelsen

Neil with his favorite book.

Neil F. Michelsen was born and raised in Chicago, Illinois. His birth data is May 11, 1931 at 5:34 am CST. A magna cum laude graduate in mathematics from University of Miami, he joined IBM in 1959, and was later transferred to the White Plains headquarters. As an iconoclast who was always interested in new ideas, he attended a 1970 astrology workshop by Zipporah Dobyns, Ph.D. and was inspired to program the hand calculations necessary to erect a natal chart on an IBM 1130 computer. This was the beginning that ultimately led to his founding of Astro Computing Services in 1973. The new business, at first operated from his home in Pelham, NY, and later in San Diego, CA,  quickly became popular with astrologers everywhere, who could now get charts and many other complex calculations easily and quickly .

In 1976 Neil began ACS Publications by publishing The American Ephemeris 1931-1980, the first in his series of computer generated ephemerides that are his most enduring legacy. As a primary pioneer of computer technology for astrology, Neil set the standards for accuracy in the field.  Although he never practiced as an astrologer himself, he became one of the most influential forces in the development of modern astrology by providing the tools that facilitated the work of astrologers worldwide. Highly active in the astrological community,  Neil served 12 years as Chairman of National Council for Geocosmic Research, and was a prime mover in bringing about the first United Astrology Congress in 1986. 

Neil passed away in 1990. Since then, Rique Pottenger, who had been mentored by Neil and was employed by him at ACS, has been head programmer, maintaining the ACS computer system as needed. 

    Neil was always very adamant that his ephemeris be updated whenever any significant new data became available, and was known to stay up all night programming when he thought such changes needed to be made. So it was that in 2006, following the International Astronomical Union’s decisions involving changes in the solar system, that we who seek to continue the Michelsen legacy, published The New American Ephemeris for the 21st Century, 2000-2100 at Midnight, Michelsen Memorial Edition. Programmed by Rique Pottenger utlilizing Neil’s programming routines, this new volume was updated with newly obtained Jet Propulsion Laboratory data and included some programming refinements not yet available within Neil’s lifetime. A text section was included with an article on the early development of computer technology for astrologers that contains excerpts from Neil’s own writing, and another article with testimonials from prominent astrologers who had benefitted from Neil’s assistance and example. 

Since then, we have republished new editions of every volume in the entire American Ephemeris series, and as of 2011, have (in response to requests) added the new Trans-Century Editions for 1950-2050 in midnight and noon versions. 

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