sidereal right ascensions, 1

[Guest guest]

Sidereal astrologers work by necessity with sidereal coordinates... or so

one would think. In practice, the truth is that while sidereal longitudes

are used, when it comes to the right ascensions and declinations (e.g. in

the calculation of parans), and the latitudes, almost always tropical

positions are used exclusively. This seems to be a contradiction, and it

brings to the surface some practical problems regarding sidereal

astrological techniques that I would like to discuss in some detail.

 

I will go by steps, and hope to some input. My exposition may contain

errors, and I am not an expert siderealist. Please consider my discussion

as basically an effort to collect previously scattered material, clarify

some issues, or simply to make the right questions.

 

 

I. Definition of the ayanamsa

 

The ayanamsa can be defined as the amount of precession (in longitude)

accumulated from one date (the epoch) to another. Since precession is a

function of time, the ayanamsa definition requires an epoch or starting

point in time. This " zero point " is traditionally described as the time

when the spring equinox coincided with the pre-defined origin of

coordinates or fiducial, which may be a fixed star, the time of a peculiar

astronomical alignment, or an empirically or statistically derived more or

less " fixed " point in space, a point that is not subject to precession.

 

The fixed point belongs to the sidereal or quasi-inertial reference frame,

against which moves or rotates with varying velocity the tropical reference

frame, subject to precession.

 

We can also define an ayanamsa as simply an angle or an arc of the

circumference between the tropical zero point and an arbitrary sidereal

zero point of longitude established by convention. This arc of celestial

longitude, as in the traditional definition, is dynamic, and changes as the

moving tropical zero point is dragged by the Earth's precessional motion

away from the sidereal zero point.

 

The difference between the two definitions lies in the absence in the

second definition of a historical coincidence in the past between the

tropical and the sidereal zero points, or in other words, the absence of

the concept of an " original " , historical sidereal zodiac, defined by its

zero point coinciding with the spring equinox of a certain moment in the

historical past.

 

The sidereal zero point can be defined anyway one wishes. The only

requisite is that its starting point in time be clearly defined. There is

no need whatsoever of a historical tradition about the beginning of the

sidereal zodiac coinciding with the spring equinox of some historical era.

Its zero point does not have to be defined in terms of a historical spring

equinox. The only thing needed is that it is fixed to a pre-defined zero

point in time.

 

In astrological, mathematical terms, whether the sidereal zero point

corresponds to some historical Spring Equinox is irrelevant.

 

The first definition is behind the several " sidereal " astrologies based on

an assumed historical sidereal zodiac the zero point of which is " truer "

than all the others. The second definition is behind the usual practice of

erecting precession-corrected solar returns.

 

Juan

[Guest guest]

Juan:

 

Your recent posts were very interesting. You brought up some points that

most of us in the sidereal community overlook. You mentioned the need to

correct Right Ascension and Declination for precession. It should be

noted that Cyril Fagan did discuss the need for these corrections in his

book Primer of Sidereal Astrology and gave formulas for making the

corrections.

 

Also I don't believe that those of us who use the Fagan/Bradley Ayanamsa

need to adjust the current ecliptic longitudes and latitudes to the

ecliptic coordinates of the epoch 221 AD. The Fagan/Bradley zodiac of

today was not determined by extrapolating forward from a special

significant moment in the past. Donald Bradley determined the location

of the vernal point for the epoch 1950.0 by his statistical

investigation of sidereal cardinal ingresses for events in modern times.

The determination of 221 AD as being the " 0 Year " when the tropical and

sidereal zodiacs coincided was made in hindsight. Perhaps we should use

the ecliptic of our present day sidereal zodiac as the reference, and

adjust the 221 AD date to conform to todays standard.

 

gary

 

=========================

On Sat, Apr 30, 2005, 7:37pm (CDT-1)

ragel wrote:

 

Sidereal astrologers work by necessity with sidereal coordinates... or

so one would think. In practice, the truth is that while sidereal

longitudes are used, when it comes to the right ascensions and

declinations (e.g. in the calculation of parans), and the latitudes,

almost always tropical positions are used exclusively. This seems to be

a contradiction, and it brings to the surface some practical problems

regarding sidereal astrological techniques that I would like to discuss

in some detail.

I will go by steps, and hope to some input. My exposition may contain

errors, and I am not an expert siderealist. Please consider my

discussion as basically an effort to collect previously scattered

material, clarify some issues, or simply to make the right questions.

I. Definition of the ayanamsa

The ayanamsa can be defined as the amount of precession (in longitude)

accumulated from one date (the epoch) to another. Since precession is a

function of time, the ayanamsa definition requires an epoch or starting

point in time. This " zero point " is traditionally described as the time

when the spring equinox coincided with the pre-defined origin of

coordinates or fiducial, which may be a fixed star, the time of a

peculiar astronomical alignment, or an empirically or statistically

derived more or less " fixed " point in space, a point that is not subject

to precession.

The fixed point belongs to the sidereal or quasi-inertial reference

frame, against which moves or rotates with varying velocity the tropical

reference frame, subject to precession.

We can also define an ayanamsa as simply an angle or an arc of the

circumference between the tropical zero point and an arbitrary sidereal

zero point of longitude established by convention. This arc of celestial

longitude, as in the traditional definition, is dynamic, and changes as

the moving tropical zero point is dragged by the Earth's precessional

motion away from the sidereal zero point.

The difference between the two definitions lies in the absence in the

second definition of a historical coincidence in the past between the

tropical and the sidereal zero points, or in other words, the absence of

the concept of an " original " , historical sidereal zodiac, defined by its

zero point coinciding with the spring equinox of a certain moment in the

historical past.

The sidereal zero point can be defined anyway one wishes. The only

requisite is that its starting point in time be clearly defined. There

is no need whatsoever of a historical tradition about the beginning of

the sidereal zodiac coinciding with the spring equinox of some

historical era. Its zero point does not have to be defined in terms of a

historical spring equinox. The only thing needed is that it is fixed to

a pre-defined zero point in time.

In astrological, mathematical terms, whether the sidereal zero point

corresponds to some historical Spring Equinox is irrelevant.

The first definition is behind the several " sidereal " astrologies based

on an assumed historical sidereal zodiac the zero point of which is

" truer " than all the others. The second definition is behind the usual

practice of erecting precession-corrected solar returns.

Juan

[Guest guest]

Many thanks for your comments and input, Gary.

 

>It should be noted that Cyril Fagan did discuss the need for these

>corrections in his book Primer of Sidereal Astrology and gave formulas for

>making the corrections.

 

I imagine that the probable reason right ascensions are normally not

corrected for precession is because the calculation would then become too

cumbersome... too many calculations to do by hand just with the tropical

ones... But now we have software

 

 

>Also I don't believe that those of us who use the Fagan/Bradley Ayanamsa

>need to adjust the current ecliptic longitudes and latitudes to the

>ecliptic coordinates of the epoch 221 AD....

 

I understand your reasoning. However, in normal practice the longitudes are

being calculated back to A.D. 221 all the time because one is using an

amount of accumulated precession (the ayanamsa) is valid only for a

starting point in A.D. 221. One is normally not aware of this fact because

the correction is seen as a simple displacement of position along the

circumference of the zodiac (a spatial consideration), without realizing

that precession is both in space and time. Precession has no meaning if it

is seen only in terms of space.

 

Anyway, the correction of the longitudes with respect to the approximate

method based on the ayanamsa is rather small, as was seen in my example,

and probably will not alter anybody's results. But the right ascensions is

another matter because they are usually not corrected for precession, and

the correction would be very large, making them impractical.

 

The fact that tropical right ascensions are used proves that sidereal

astrology is " sidereal " only approximately, and only sometimes. This is a

real inconsistency, or to use a " harder " word, an astronomical absurdity,

however valid or good the astrological results are.

 

The impracticality of correcting for precession the right ascensions and

declinations by an amount equivalent to the correction that is being

applied to the longitudes disappears if instead of a " universal " sidereal

ecliptic (zodiac) one uses the tropical ecliptic (zodiac) of the time of

birth as the starting point of the coordinates, and then calculates

precession with respect to it, effectively making the tropical zodiac of

the time of birth into a sidereal " fixed " reference frame. In such a case

the corrections for precession of the tropical coordinates will always be

relatively small.

 

Juan