Using The Position of Sirius - Better Than Precessional Dating?

In an attempt to “re-date” dynastic Egyptian chronology or better said, to assign more accurate periods to the reigns of Kings and Pharaohs, astronomers and Egyptologists have recently combined their efforts in order to use the heliacal rising of Sirius as a “source of dating”. A special software program has been developed by Karine Gadré, the Associate Researcher at the Department of Astrophysics of the Midi-Pyrenees Observatory in Toulouse, France.

The original program which determines the heliacal rising for any star taking in account the date, latitude, elevation and a number of atmospheric variables is available from her company called CultureDiff (www.culturediff.org). The software works mainly on the basis of historical references and demonstrates that Sirius neither follows a tropical year of 365.2422 days nor a sidereal year of 365.2564 days. Evidently, the length of a Sirian year is almost exactly 365.25 days according to the program.

Example: Given the same atmospheric conditions for Alexandria (latitude 31,22 degrees), the heliacal rising of Sirius occurs in 1950 CE on August 5 and in 3421 BCE on July 19 (Julian Calendar) [which is equivalent to June 21, 3420 BCE Gregorian calendar]. Hence, in some 5370 years Sirius has moved approximately 45 days away from the Summer solstice in 3420 BCE. Of course, over the same period the stars of the Zodiac would have moved by roughly 75 days due to the effects of precession.

Like with other available astronomical software, the apparent motion of the stars is programmed for the slow retrograde movement with respect to the fixed position of the equinox or solstice in the calendar (i.e. the rate of precession is not based on Hipparchus’ or Ptolemy’s figure or for that matter on an Egyptian agricultural year of 365 days, but on a more modern value of 50.26” per tropical year).

According to the current theory of lunisolar precession the pole, and therefore the equator of the Earth is supposed to “wobble” over a period of roughly 25800 years relative to the position of the fixed stars and the Sun. In other words, if we were to imagine the Earth ‘fixed’ in its revolution around the Sun at the time when Sirius is in conjunction with the Sun (e.g. during the Summer solstice), an observer would not only notice changes in the declination of Sirius and the other stars, but simultaneously equal changes in the declination of the Sun. In practice, however, Sirius does not show any significant variations in its position relative to the Summer solstice.

In order to account for the unusual motion of Sirius, which is minimal relative to the Summer solstice and exceptionally high with respect to the stars of the Zodiac, Karine Gadré offers the following explanation:

“The low change in the celestial coordinates of Sirius comes from its high proper movement, which partly compensated the effects of precession under the Dynastic Period. […] In order to better understand how the proper movement of Sirius can partly compensate the effects of precession, do not only take into account the numerical values of the speed vector. Take also into account the position of Sirius on the celestial vault at a given instant and the direction of the speed vector.”

Now we know that the proper motion of Sirius (i.e. of the Sirius system) over a period of some 5400 years is less than 2°:

"For a long time astronomers had been noticing anomalies in Sirius' proper motion; this motion, well known since Halley's time is equal to 0.0375" in RA (Right Ascension) and to 1.207" in D, (Declination), which gives a yearly resultant motion of 1.32" in the direction of 204°, which is noticeably to the south. In 1834, Bessel showed that the anomalies consisted mainly of deviations between the star's theoretical position and its actual position; these distinctly periodic differences, especially in right ascension, may be as great as 0.321", which is a considerable amount with regard to meridian observations. Overall, instead of moving through space in a straight line, Sirius appears to display a wavy trajectory."

Dr. P. Blaize, Le Compagnon de Sirius, Bull. de la Société astronomique de France (1931)

Modern astronomical references indicate that the proper motion of Sirius ranges from RA: -0.038 to -0.553 arcsec/a, whereas values for the Declination are given anywhere from 0 to -1.205 arsec/a.

Such data hardly “compensates” for a precession in the longitude of more than 50” per year!

In terms of sidereal transit time measurement, the mean sidereal rotation period of the Earth with respect to the fixed stars is said to be about 86164.101 seconds, whereas the mean sidereal day relative to the position of the vernal equinox is 86164.09054 seconds. According to the “historical data” of Sirius based on observations of its heliacal rising, it appears that a sidereal day, as measured with respect to Sirius (i.e. its mean transit period), is approximately 86164.095 seconds.

A similar value of the mean transit period of Sirius (86164.09281 s), which in reality is closer to a tropical day of 86164.091 seconds, has been confirmed by Karl-Heinz Homann as part of his long-term observations of Sirius during a period of more than six years from 1994 to 2000. His observations of Sirius began in 1989 and continue to the present day, furthermore confirming the astronomical fact that Sirius does not show any precession. The minimal motion of Sirius relative to the Summer solstice, for example, cannot be explained by conventional luni-solar precession dynamics, general precession variations or the geometric relationship between the precession cycle and the declination of a star.

In other words, if Sirius is not our Sun’s dual it would have to behave like any other star and its mean transit period could not be equal or close to equinoctial time.

Over a period of six years Sirius should have changed its position by 6 × 1223 seconds (i.e. more than 2 hours), which is said to be the time difference between the tropical year and the moment our Earth crosses the imaginary conjunction line between Sun and Sirius. However, the observations have shown that after six years of continued measurement Sirius crossed the meridian only 5 seconds later than tropical time, instead of 9.12 ms/day or 3.34 s annually (6 × 3.34 s = approx. 20 seconds).

According to the latest VLBI data (International Earth Rotation Service) and the current astronomical understanding of precession (i.e. lunisolar “wobble”), the conventional duration of Earth’s inertial spin period is 86164.09890369732 seconds regardless of precession.

http://hpiers.obspm.fr/eop-pc/models/constants.html#rotation

If that assumption were to be true, the mean transit period of Sirius can not be several milliseconds shorter in duration each sidereal day, than Earth's mean rotation period relative to inertial space!

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