#### FraterAC

##### Well-known member
Let's stop and ask what a progression is.
Progressions are based on the correspondences between certain cycles creating resonances in different magnitudes of time. Earthly rotation (a day), the orbit of the Earth around the Sun (a year), and the orbit of the Earth and Moon around their center of mass (a lunar month). The cycles have to correspond precisely and be consistent.
There is an effect similar to a fractal image created by this. The circle of a day, of a month, of a year, like gears.
How we calculate progressions (and directions) has to relate precisely to these cycles and they need to correspond precisely; in other words each circle must equal the same circle, day circle = month circle = year circle. And they, just BTW, need to correspond to actual astronomical events.
So is this all just a pipe dream?
No, because if one makes these correspondences, the system works.

#### FraterAC

##### Well-known member
In Charles A. Jayne's Progressions and Directions he says the measure of directions should be
"The true motion of the Sun, and not on the fictitious mean motion -- the motion of Naibod or 59' 08.33" -- or the equally fictitious one degree a year of Ptolemy," (page 8).
By that he means the solar arc of the Sun in both right ascension and Zodiacal longitude, as would be calculated in Secondary progressions. Not as of the day of birth, and not the mean motion. He (as Johndro did as well) advocates directing the MC both on the equator by RA and on the ecliptic by longitude (which corresponds to directing it by Solar Arc).

#### FraterAC

##### Well-known member
The administrator of the AstroSeek site, with its free software many members of this forum use, was not particularly clear on how their site does the calculation.
The administrator of the Astro-Seek site subsequently responded to my persistent nagging (thank you, Petr9!) with the following response:

"It´s actually pretty simple - and you can forget all your previous ideas

https://horoscopes.astro-seek.com/c…

1) first you find the time difference between date of progressions and birthdate ... and divide it by "1-year" (365.242189 days) - to get the ratio 1day-for-1year

Progressions: 2023-12-08 00:00 :00 (UT)
Date of birth: 1983-05-09 11:51 :30 (UT)
Δ delta difference: 1280664510 seconds
1280664510/365.242189 = 3506343 seconds

2) now you +add those 3506343 seconds to birthdate 1983-05-09 11:51 :30 (UT)
and get 1983-06-19 01:50 :33 (UT)

This is the real transit date and time, which is used for positions of "progressed" planets.

a) ARMC 1 Naibod calculates MC/ASC axes "artificially" to lock the slow movement (cca +1° deg per year)

b) ... but ARMC 361°/prog.day uses THIS real transit date and TIME also for calculation of real MC/ASC axes - as it follows the continous earth rotation (1 year - will match 1 day & also 1 earth rotation)"

#### FraterAC

##### Well-known member
This writer responded:
"What you are describing is another way I have been calculating the Quotidian angles. What I wanted to know was how it was being done HERE (ie Astro-Seek).

To adjust the progressions to calculate based on the Sidereal rather than the Solar day, the relationship of a day to a year represented by the factor 365.242189
needs to be replaced by

366.2421992

Cyril Fagan and R. C. Firebrace referred to this as Bija correction.
If this is done the Secondary Moon and angles better correspond to observed effects. This has been observed by Fagan, Johndro, the Church of Light, and more recently by Dr. Ron Tiggle of Kepler College, and David Cochrane.

Bija correction also makes Tertiary progressions useful."

#### FraterAC

##### Well-known member
As to how another of the values for Sharon Tate’s Quotidian angles for the time/day of her transition can be calculated, for the entry in the table labeled Calculated Time, in the entry above,

#18

the following calculation (done in Excel) was used

 Event (transition) date (adjusted for time zone) 8/9/1969 1:30​ Ms. Tate's Nativity 1/24/1943 17:47​ Days 9,693.32153 Bija-Adj Rate 366.2421992​ Progressed interval, days 26.46697062​ Date|Time for Progressed angles 2/20/1943 4:59:26​

Note that Excel actually stores dates and times as numbers, so can do the addition and subtraction of one Date/Time from another for you. By formatting the cells the values can display in either a Date|Time or Days|decimal format.

Calculating a chart at Ms. Tate’s birth locality (Dallas Tx) using the above date yields the angles

Midheaven Libra 24:19
Ascendant Capricorn 05:53

As in the table.

#### FraterAC

##### Well-known member
The upshot of all this is, that to calculate the angles of the progressed horoscope consistent with the formula of “a day equals a year,” then logically, one must use some kind of Quotidian calculation for the angles, and not graft onto the progressed horoscope some kind of direction technique, as described earlier.
That is going to mean using a formula like the ones given above, in the last two posts.
As to the question of what constitutes a “day” check out my thread on that topic here.

#1

For the question of the length of a year, in days, that equates to one 24-hour calendar (or ephemeris) day, multiple researchers and a growing body of evidence lead one to the conviction that it must be 366+ (about which more later), NOT 365.242189. That is, the progression calculation must be based on the Sidereal, not the Solar, day; it must be Bija-corrected.

#### FraterAC

##### Well-known member
that it must be 366+ (about which more later)
In the conversation with Petr9 on the Astro-Seek forum, occurred the following exchange:

'Btw do you have any idea why there are these 2 slightly different Sidereal days values?:

"366.2421992"
- used by OPA astrology

"366.2563992"
- used in Astro Gold and Janus"

FraterAC replied:

"366.2421992 is the sidereal days value based on the MC returning to a point in the Zodiac (ecliptic) - so it´s based on a tropical year.
366.2563992 is a sidereal days value based on the MC returning to the location of a fixed star (or adjusted for precession) - so it´s based on a sidereal year.

The difference in time -- 20 min 26.88 seconds -- is the average amount of time it takes for the Earth to rotate 50.3" of arc -- the average amount of annual precession.

Obviously over time this difference is going to add up. Is it going to add up enough to make a difference in the 90 or so days we consider the amount of time needed to compute secondary progressions for an average lifetime? Probably not. Tertiary progressions would cover 3 to 4 years after the birth, making a difference of about 3´ of arc. Is that significant? Maybe.

Minor progressions (lunar revolution = 1 year) do not use a day as a basis so are not affected (by this question, anyway)."

I had been using the first value, 366.2421992. This factor assumes the "year" being considered is the tropical year. Which seemed reasonable on the face of it, BUT the tropical year is in motion. The vernal point is precessing at the rate of approximately 50.3" per year. Therefore, the factor 366.2421992 IS NOT a complete circle, and cannot logically be the equivalent of one full 360 degree revolution of the Earth on its axis.
Therefore, it's recommended, and I will be using in the future, the factor 366.2563992 which represents the sidereal year, which IS one full 360 degree circle.
Admittedly, the difference is very small. In a lifetime of 75 years it will amount to approximately a minute of arc on the Midheaven. But this factor does preserve the fractal integrity of the calculations (and may have other effects).
Note that this does not have anything to do with whether one is of the Siderealist school, or uses the tropical Zodiac. The considerations above are relevant in either case.