SSRY and Ephemeris

[kokab]

I have Michelsens Sidereal Ephemeris where each month has a daily listing of the S.S.R.Y. When I subtract current SSR's ST from the next SSR's ST plus 24 hours it dosen't match number listed on the SSRY date. My natal chart is 10/17/62 and my Sun is only minutes away from Spica at 29 23 Virgo. Subtracting LST 9 54 19 from 16 04 18 plus 24 I get 30 09 59 for years 2014-2013 on October 17 both days.Ephemeris says 30 12 11 for Oct 17 2013..I see there is a mean rate but I thought Michelsens ephemeris calculates SSRY exactly.Request any help about this matter/Thank You-Harold

[Jim Eshelman]

Thanks, Harold. I think you're correct that there is an error in that column - I don't think you can rely on it.

I just did a spot test for my last SSR and got an answer accurate within 1 minute; I'd have expected better. I see you got worse.

A bit of history: Sidereal ephemerides in the past had the ASSI column, which was a real boon for PSSR work when it was believed the PSSR should be calculated at an apparent solar rate. (Many of us no longer think that way: It seems it has closest hits at a mean rate.) When Neil and I were designing the ephemeris in 1981, I emphasized the importance of the ASSI column. I never asked about the SSRY column and probably never looked too closely at it - I was always going to calculate that myself.

I don't know what the calculation bug was, but apparently there is one (and, apparently, that column wasn't proofed enough), for which I apologize.

[kokab]

Mr. Eshelman-Thank You for the reply.I have been using the Ephemeris to calculate the PSSR.I downloaded your calculator where I could see how the input values correspond to the methods in the book.Thanks for all you do-Regards-Harold Queens NY