I was looking up the time of the autumnal equinox this year, using the NASS dialist companion (version 1.1) to determine when declination=0. The value (approximately 18:40 Eastern Daylight time on 9/22) differs by 25 minutes from the value given at most other websites (such as http://www.archaeoastronomy.com/almanac.html), being around 19:05 Eastern Daylight Time. Any one know why there is a discrepancy?
Bill Gottesman Burlington, VT 44.4674N, 73.2027W
