I wish I could help, Tienka, but unfortunately I know nothing about Sylvia Delong that isn't immediately apparent from her three known published books on astrology that I'm aware of, the others being:
Mystical and Mundane Interpretations (1979);
Charting Presidential Elections (1982).
She is not listed in 'Astrological Pioneers of America', which took the brief of only including astrologers born in 1923 or earlier, a criterion that presumably excluded Ms. DeLong. Depending on her age at the time her books appeared, she could very possibly still be alive today and for many years yet to come. I hope someone who knows her personally will eventually find this strand in a random search engine search and answer you, or refer your query to her directly.
At some point I'll check my shelves for those two titles above and look for clues. Trying to find modern softcover books in this room is a bit like looking for needles in a haystack, unfortunately, as there are so many shelves, but I know I have them. However, I suspect that the AFA would have been able to help you if she had left any!
Meanwhile, I suggest you try contacting Janice Brown, if you have not already done so, to see if she knows anything about Ms. Delong's life beyond what she mentions on this page:
http://www.janicebrown-astrology.com/janicebrownbio.htm
PS: I don't know if this merely duplicates what is already mentioned in her book on horary, as my copy of that is lurking somewhere else I haven't got to yet in the ongoing optical speed-scan procedure, but I found 'Charting Presidential Elections', which does describe her life a little, in the blurb at the back, thus:
Sylvia De Long, for many years a full-time astrological consultant, well-known lecturer and teacher of astrology, resides in the tiny community of Cassadaga, Florida. From this quiet little town she counsels her clients throughout the country and abroad, and travels extensively to present workshops and astrological retreats.
She has enjoyed considerable newspaper, radio and TV publicity with her forecasts on the Apollo 11 Moonshot, the troubled Skylab mission, and other space shots. Fifty-two American and Canadian papers carried her own story forecasting the success of Apollo 11.
Starcast, her own TV show, was presented daily on several channels for over two and a half years. She has been a staff writer for one of the leading Florida magazines and columnist for a major cosmetic firm, and in earlier years counseled through her columns in metaphysical publications.
She was ordained a minister of the Universal Church of the Master in 1967....
She is a Professional Member of the AFA, certified by the Astrologers' Guild of America, Founder and President Emeritus of the Astrological Research Guild, and a Past President of the Lake Wales Business and Professional Women's Club.
The part I missed out just listed her books, as I have already done.
It sounds as though she created her own astrological organisation in the 'Astrological Research Guild', but I have never heard of it in any other context and presume it remained small.
The Astrologers' Guild of America seems to have been a fairly large organisation in its time, however, but I gather that its activities were effectively suspended quite some years ago now. I presume that she took professional competency examinations of some kind at the Guild, based on the above description.
Perhaps you already have this book, but if not, I hope that was a useful start!
By the way, she seems likely to have learned astrology within her family initially, having been born into a family that had an enthusiasm for it, perhaps without attaining her level of notability. She states in the Introduction to 'Charting Presidential Elections' that the book is going to present the method...
employed by my family and myself... [which] has proven reliable for us since the memorable 1948 Truman-Dewey race
.
PPS: I just found 'The Art of Horary Astrology in Practice' in my shelves and notice that the blurb about the author there is in fact lengthier and more detailed than the equivalent in 'Charting Presidential Elections'. So I'm sorry for telling you things you already knew! She clearly had some other books published too that I have never seen before, which were out of print already by the time these books were printed and have remained so ever since, and which do not feature in library records either.
