sidereal right ascensions, 4

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Normally, sidereal astrologers do not apply precession to the coordinates

of a radix. What they do is REPRESENT THE LONGITUDES IN THE SIDEREAL

ZODIAC, i.e., add the ayanamsa to the longitudes only, keeping the

representation of latitude, declination, and right ascension strictly tropical.

 

In order to apply rigorous precession to the longitudes, latitudes, right

ascensions, and declinations, we need to know the epoch or zero point of

the coordinates. Having the position of the ayanamsa in the tropical zodiac

--the usual procedure-- is not enough. We need to know when in time the

ayanamsa was exactly zero.

 

Using the Bureau des Longitudes precession formulas, the resulting epoch

(the root of the polynomial used to calculate the Fagan/Bradley Ayanamsa)

is September 11, A.D. 221, julian day 1802031.7973. This date is dependent

on the numerical quantities of precession in the ecliptic and may vary if

one uses other quantities. The BdL formulas, for example, may have an error

of in 1.8 " or 1.9 " in A.D. 221, so this date may be off by about 2 weeks.

 

data used for the example: J.F. Kenedy dies, November 22 1963 UT 18h30m00s.

 

Let's see the positions with the usual procedure:

 

longitude latitude rightasc. decl.

Moon = 17Cp00'36 " -2,33' 20h57m46s 19s51

Sun = 5Sc30'10 " 0,00' 15h50m10s 20s06

Mercury = 15Sc30'59 " -1,36' 16h31m20s 23s30

Venus = 27Sc13'01 " -0,55' 17h22m30s 24s05

Mars = 26Sc17'32 " -0,49' 17h18m30s 23s55

Jupiter = 15Pi34'59 " -1,30' 0h38m26s 2n30

Saturn = 23Cp05'00 " -1,12' 21h20m35s 16s48

Uranus = 15Le34'57 " 0,46' 10h46m36s 8n36

Neptune = 21Li41'31 " 1,43' 14h55m52s 14s58

Pluto = 19Le50'09 " 13,40' 11h23m20s 18n50

 

The rigorous application of precession gives:

 

Moon = 16Cp59'43 " -2,22' 19h15m09s 24s56

Sun = 5Sc29'41 " 0,12' 14h12m53s 13s17

Mercury = 15Sc30'37 " -1,23' 14h50m16s 17s58

Venus = 27Sc12'34 " -0,42' 15h38m50s 20s24

Mars = 26Sc17'05 " -0,35' 15h35m06s 20s05

Jupiter = 15Pi34'09 " -1,33' 23h09m23s 7s10

Saturn = 23Cp04'18 " -1,03' 19h40m32s 22s43

Uranus = 15Le34'18 " 0,41' 9h13m11s 16n58

Neptune = 21Li40'44 " 1,53' 13h22m53s 6s47

Pluto = 19Le46'26 " 13,36' 9h48m19s 27n52

 

The first tabulation is a simple representation of longitudes after a

change of the zero point in the circumference. Although this is what is

usually called " sidereal " , astronomically speaking it makes little sense.

 

The second tabulation shows the positions in a truly sidereal reference

frame, defined by the ecliptic and equinox of the zero point in time of the

Fagan/Bradley ayanamsa. Note that, when the latitude is high as in the case

of Pluto, the difference in the longitude is more significant.

 

differences in longitude latitude:

 

Moon = -0'53 " + 11'

Sun = -0'29 " + 12'

Mercury = -0'22 " + 13'

Venus = -0'27 " + 13'

Mars = -0'27 " + 14'

Jupiter = -0'50 " - 3'

Saturn = -0'42 " + 9'

Uranus = -0'39 " - 5'

Neptune = -0'47 " + 10'

Pluto = -3'43 " - 4'

 

Even though the time spanned from A.D. 221 to 1963 is considerable, the

differences in longitude are small, except in the case of Pluto, although a

difference of 4 arcminutes can still be considered small. The differences

in latitude are larger, but perhaps not very significant because the

latitude is little used anyway. The only common use of latitude that I can

think of is for converting to right ascension and declination.

 

That the differences are small is encouraging. It means that one could use

a more rigorous precession method without having to deal with very

different results that would make them impractical.

 

The right ascensions and declinations are another matter, because in

sidereal practice they are strictly tropical, they are never precessed, for

reasons unknown to me:

 

differences in right ascension between tropical and A.D. 221:

 

Moon = -0h42m37s

Sun = -0h37m17s

Mercury = -0h41m04s

Venus = -0h43m40s

Mars = -0h43m24s

Jupiter = -1h29m03s

Saturn = -0h40m03s

Uranus = -1h33m35s

Neptune = -1h32m59s

Pluto = -1h35m01s

 

differences in declination (in degrees and arcminutes):

 

Moon = +5,05'

Sun = -6,49'

Mercury = -5,32'

Venus = -3,41'

Mars = -3,50'

Jupiter = -9,40'

Saturn = -5,55'

Uranus = +8,22'

Neptune = +8,11'

Pluto = +9,02'

 

The differences in right ascension and declination, logically, are very

large, the coordinates totally different. Using them would require a lot of

experimentation in a previously unexplored field (as far as I know), and

personally, or intuitively, I am not tuned to this way of handling the

right ascensions.

 

However, using precession-corrected right ascensions and declinations from

the time of the radix will result in very small differences from the

strictly tropical coordinates, with the advantage that they would be

sidereal, instead of working sidereally sometimes, tropically others, or

using both sidereal and tropical within the same calculation (as in the PSSR).

 

Juan