MAGICSUN

Over the past two-and-a-half millennia, this wobble has caused the intersection point between the celestial equator and the ecliptic to move west along the ecliptic by 36 degrees, or almost exactly one-tenth of the way around, to the border of Pisces and Aquarius. This means that the signs have slipped one-tenth — or almost one whole month — of the way around the sky to the west, relative to the stars beyond. https://www.livescience.com/4667-astrological-sign.html This is reality today. It has never been adjusted for in any calendar. Just because wikipedia mentions precession of the equinoxes, the Gregorian calendar does not include an adjustment of 1 day every 72 years.

Thanks Andrew. Yes the calendar corrected equinox drift due to earth rotation discrepancies, not Axial precession.

Tens of arc seconds is good, but I was hoping to be able to measure for instance 22.4 arc seconds. The solstice date changes you refer to are adjustments for the inexact year length of 365.2425 days, and ongoing inaccuracies due to earth's speed of rotation gradually slowing down. There has never been a calendar adjustment for axial precession. The position of the stars have moved 30 degrees over the past 2150 years, as evidenced by the shift in astrological signs in this period. Hence the relative date of solstice has shifted one day every 71.6 years. Yet the calendar has never been adjusted for this.

Thanks Andrew I think I understand that. More specifically I was asking if a good amateur telescope could position with accuracy to 0.1 seconds? Also can somebody explain if the stars have moved due to earth's axial precession at a rate of 1 degree every 71.6 years (or 20 minutes per year), why hasn't the date of the solstice also changed?

Is it possible to measure earth's axial procession with a good amateur telescope? It would require measuring the movement of a star in one year to the accuracy of a decimal point in seconds. I understand it is also vital to make the observations at precisely the same time. Any suggestions greatly appreciated.