<HTML>Sorry, Dave.
My mistake. I did a brainfart too. (my dumb finger went one column over too far in my notes into the autumnal-eqx and the wrong year - ahh, it feels great to be wrong sometimes). Here are the correct locations for the veqx's in their relevant epochs (e = east):
10.5kBCE : e-Leo
4000BCE : e-Taurus
2001CE (present) : w-Pisces
And the Gregorian calendar dates for when the sun sits on this spot:
10.5kBCE : June 6
4000BCE : April 22-23
2001CE (present) : March 20
So I have to backtrack here.
In 4000BCE you used March 21 as the beginning date, and again this date after navigating 25,770 yrs. Ok. What you saw was a different position for the sun, and weren't so concerned with v-eqx position in testing the accuracy of the program.
So what I'm getting at is....to find the real accuracy, don't use a calendrical date - use the position of the v-eqx (you could even use the a-eqx or eith of the solstices). So after c.26,000 years, the marker should near it's original position.
Now, when you used dates, not only is there a shift in the time of year for the markers, but there are 11 days lost during Oct of 1582. So stick to the marker positions.
The results of SNP:
From Apr 22/4000BCE (v-eqx) to Feb 20/21,776CE (v-eqx) = 21,776yrs
Location of v-eqx in both : e-Taurus
J2000 v-eqx position : 4000bce ; RA 5h 28m 45s / Dec 24 01' 25"
J2000 v-eqx position : 21,776 ; RA 5h 22m 50s / Dec 22 03' 34"
Therefore an angular offset of about 2deg, and with the sun being c.31' (half deg) in angular size, the postions of the v-eqx's can be positively identified with the modern precessional cycle defined as c.25,776 years. Also, any congruent offset in the precessional match is further exemplified becuase of centre locking features which can vary. (I was set to 25 44' 10" angular view, where a Telrad would make the RA/DEC's more acute).
Therefore, SNP refelects the accuracy of current astronomical data.
__________
Since I provided you with incorrect figures (an error in locating the data - 'duh' for me) you will have to re-do the sim to check the accuracy of SkyMap. All apologies.
Avry</HTML>
