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Re: When did the Atumnal Equinox occure this year?
From: Peter Hakel
Date: 2019 Sep 27, 05:52 -0700
From: Peter Hakel
Date: 2019 Sep 27, 05:52 -0700
Frank, you asked about the values of Sun’s SHA around the autumnal equinox this and the next year.
The attached spreadsheet displays the right ascension of the Sun (“Alpha” in cell A61), which works equally well as the SHA. For September 23, 2019 we have
UT = 07:49:58
Alpha = 179.9999899 degrees
UT = 07:49:59
Alpha = 180.0000003 degrees
which are the two times bracketing the change in declination sign reported in my previous post.
Delta T is computed to be 71.4 seconds (cell B16).
For September 22, 2020 I get
UT = 13:30:31
Alpha = 179.9999899 degrees
UT = 13:30:32
Alpha = 180.0000003 degrees
Delta T is 72.0 seconds. The declination sign change from N to S is bracketed by these two time instants as well.
Peter Hakel
