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Most common way to progress the MC in longitude?
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Wed Jun 24, 2015 8:55 pm    Post subject: Most common way to progress the MC in longitude? Reply with quote

Hi,

in my home country in europe we almost exclusively progress or direct the MC on the equator in right ascension. Therefore I like to learn more about how progressing the MC in longitude is done?

What is the most common (right?) formula to progress the MC and houses with true solar arc in longitude?

There are three possible formulas:

Method 1:
1.1. Measure the true solar arc on the ecliptic in longitude.
1.2. Add this arc in longitude to the MC in right ascension. *
1.3. From this progressed MC in right ascension (RAMC) calculate the houses in longitude.

Method 2:
2.1. Measure the true solar arc on the ecliptic in longitude.
2.2. Add this true solar arc in longitude to the MC in longitude
2.3. Convert this progressed MC in longitude to right ascension.
2.4. From this progressed MC in right ascension (RAMC) calculate the houses in longitude.

Method 3: (formerly wrong written 'method 2', see below):
2.1. Measure the true solar arc on the ecliptic in longitude.
2.2. Convert this true solar arc in longitude to right ascension
2.3. Add this true solar arc in right ascension to the MC in right ascension
2.4. From this progressed MC in right ascension (RAMC) calculate the houses in longitude.

* Adding an arc measured in longitude to a MC in right ascension seams not right to me.

Astrology programs that calculate Secondary Progressions or Primary Directions in true solar arc in longitude:
Method 1: Placidus 7 with Primary Directions
Method 2: Janus 4.3 with Secondary Progressions
Method 2: Solar Fire with Secondary Progressions and van Dam Primary Directions
Method 3: Don't know any program that calculates method 3. Is there one?

Here is an example horoscope of Queen Elizabeth from Astro-Databank:
http://www.astro.com/astro-databank/Elizabeth_II,_Queen_of_England

Natal chart: AC 21°22'44" Capricorn, MC 25°32'48" Scorpio

Secondary Progressions with true solar arc in longitude for April 21. 2015:

Method 1 (Placidus 7):
Progressed: AC 21°57'52" Gemini, MC 16°10'51" Aquarius.

Method 2 ('Solar Fire' and 'Janus'):
Progressed: AC 26°38'19" Gemini, MC 20°58'40" Aquarius.

Chris


Last edited by Chris Meyer on Thu Dec 03, 2015 4:17 am; edited 22 times in total
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Atlantean



Joined: 14 Aug 2009
Posts: 396

Posted: Thu Jun 25, 2015 6:11 am    Post subject: Reply with quote

For progressions and regressions, the Angles/Cusps should move according to Right Ascension as that will introduce smaller orbs than using Longitude.

...and I realize this doesn't answer your question. Wink
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Thu Jun 25, 2015 11:06 am    Post subject: Reply with quote

Hi Atlantean,

as you already supposed my question is about the correct formula. Not if the methode makes sence or if its results are precise.

Chris
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jventura



Joined: 04 Jan 2011
Posts: 293
Location: Portugal

Posted: Thu Jun 25, 2015 1:31 pm    Post subject: Reply with quote

Hi there,

I'm having trouble understanding what you are trying to do.. Are you talking about Primary Directions? Could you give us an example of what you are trying to calculate?


Regards,
Joćo Ventura
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Thu Jun 25, 2015 6:38 pm    Post subject: Reply with quote

Hi Joćo,

both secondary progressions and primary directions. In secondary progressions the angles are directed primary anyway.

I suppose that for secondary progressions MC and house progression / direction with True Solar Arc in longitude is quite common in USA. I found out also that "True Solar Arc in longitude" is used for primary directions called "Wim van Dam" method: www.astrosoftware.com/WimPrimaries.htm

I added an example horoscope with secondary progressions to my initial post. MC and AC are progressed / directed with the two different methodes I mentioned. Hope that helps to make it clearer.
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Southern Cross



Joined: 10 Jan 2014
Posts: 49

Posted: Fri Jun 26, 2015 7:01 am    Post subject: Reply with quote

Hi Chris,

I have a question too. It could be part of what you want to find out.

When one compares the angles of an solar arc chart to the angles of a progressed chart done with solar arc in long (for the same time) the MC's are the same but the AC's differ.

example for queen elizabeth:
1th of July 2015 Solar Arc AC 15°05 aries and progressed solar arc in long AC 25°00 gemini

Why do the AC's differ?
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Fri Jun 26, 2015 9:36 am    Post subject: Reply with quote

Southern Cross this is a complete different question. Would you please be so kind and open another thread for this. Thank you.
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jventura



Joined: 04 Jan 2011
Posts: 293
Location: Portugal

Posted: Fri Jun 26, 2015 10:59 am    Post subject: Reply with quote

Hi there Chris,

I don't know much about true solar arcs and secondary directions since I don't use them in my own practice.

But if it is similar to how to "primarily" direct a planet to a meridian (such as MC), I use something like your 2nd formula. First you must convert the planet's position from ecliptical to equatorial coordinates, and then to a subtraction to get the arc of direction (eg. RA Promissor - RAMC).

In my opinion, the 1st formula is mixing potatoes with apples. You should not add something measured in ecliptical degrees to something in equatorial degrees since they are different referentials. That is why we must project a planet's ecliptical lat/lon to its respective position in the equator (ra/decl) and work in equatorial coordinates. And we do this because, for primary directions at least, the "rule" is "one degree of RA equals aprox. one year".

I'm being over-simplistic, but I hope this makes sense for your case of solar arcs and secondary directions.


Regards,
Joćo Ventura
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Fri Jun 26, 2015 5:43 pm    Post subject: Reply with quote

Hi Joćo,

Quote:
I use something like your 2nd formula. First you must convert the planet's position from ecliptical to equatorial coordinates, and then to a subtraction to get the arc of direction (eg. RA Promissor - RAMC).

This is a well known method the astrologer 'Placidus' invented. In the astrology program 'Morinus' it is called 'True Solar Equatorial Arc'.

My question is about 'True Solar Ecliptical Arc'. This is a modern invention mostly used for Secondary Progressions in USA and for Wim van Dam Primary Directions.

Quote:
In my opinion, the 1st formula is mixing potatoes with apples. You should not add something measured in ecliptical degrees to something in equatorial degrees since they are different referentials.

Yes that is just what I'm thinking too.

Thank you for this valuable assessment of an astrology programmer.

Chris
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Ruud66



Joined: 05 Apr 2009
Posts: 46
Location: Amsterdam, Netherlands

Posted: Fri Jul 10, 2015 11:25 am    Post subject: Reply with quote

jventura wrote:
In my opinion, the 1st formula is mixing potatoes with apples. You should not add something measured in ecliptical degrees to something in equatorial degrees since they are different referentials.

I don't see it that way. I see this as the correct way of using the true solar arc. You're not mixing up different referentials here. This becomes clear if you view the solar arc in longitude as "part of a year" and if you view the arc of the MC in R.A. as "part of a day". So you are actually dealing with different temporal arcs.

Then I must say that Wim van Dam uses the method of adding the true solar arc in longitude to the MC in longitude.

And most traditional astrologers are not so interested in the secondary progressions (a rather recent invention by Placidus) and direct all points using Naibod or some other key.
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Tue Jul 14, 2015 7:22 am    Post subject: Reply with quote

Hi Ruud66,

did you read my intial post of this topic and recognised the difference between method 1 and method 2?

As written there both common astrology programs "Solar Fire" and "Janus" are calculating Secondary Progressions with True Solar Arc progressed MC like method 2.

In "Solar Fire" you find this option in Menu / Preferences / Progs/Dirns / Chart Angle Progression: "SA in Long".

In Janus: Menu / Calculate / Transists/Directions/Progressions.../ Options / Progressed MC: "True SA Long".

Also Wim Van Dam Primary Directions you mentioned are based on method 2 (calculated by "Solar Fire" and "Sirius").

So I suppose method 2 is the most common way to progress or direct the MC in True Solar Arc in longitude. If its the only correct way to do it I'm not 100% sure about.


Last edited by Chris Meyer on Thu Jul 16, 2015 2:05 am; edited 1 time in total
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Ruud66



Joined: 05 Apr 2009
Posts: 46
Location: Amsterdam, Netherlands

Posted: Tue Jul 14, 2015 1:37 pm    Post subject: Reply with quote

Chris Meyer wrote:
did you read my intial post of this topic and recognised the difference between method 1 and method 2?

Hi Chris, of course I read your post, but I only said some things I wished to react to. In the first method the solar arc in longitude is directly added to the RAMC, in the second method the solar arc is added to the RAMC in right ascension.

Quote:
As written there both common astrology programs "Solar Fire" and "Janus" are calculating Secondary Progressions with True Solar Arc progressed MC like method 2.

Also Wim Van Dam Primary Directions you mentioned are based on method 2 (calculated by "Solar Fire" and "Sirius").

I don't know much about the different calculation programs. I always calculate progressions etc. in my own way using a spreadsheet I programmed myself.
One thing I know for sure: Van Dam doesn't use method 1 or 2.

{edit} this has been corrected in the first post by Chris; method 2 is used by Van Dam.{/edit}

He uses the method I outlined in my previous post. I know this because I have the original article in which he published his system of primary progressions for the first time. This was in the Dutch astrological magazine "Spica" somewhere in the 1980's.

Quote:
So I suppose method 2 is the most common way to progress or direct the MC in True Solar Arc in longitude. If its the only correct way to do it I'm not 100% sure about.

I don't think there is a "correct" method of progressing the angles. This technique of progressing the angles in the secondary progressed chart is in itself a modern mutation of primary directions and using that in conjunction with the secondary progressed chart is a questionable practice. If anything is mixing potatoes with apples then this is it.

I'm sorry if my answer disappoints you, as I realise I can't offer any clear-cut answers.


Last edited by Ruud66 on Thu Jul 16, 2015 4:37 pm; edited 2 times in total
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Ruud66



Joined: 05 Apr 2009
Posts: 46
Location: Amsterdam, Netherlands

Posted: Wed Jul 15, 2015 2:17 am    Post subject: Reply with quote

I found this article by David McCann:
http://www.skyscript.co.uk/pran.html

He advises progressing the RAMC with the true solar arc all in right ascension.


Last edited by Ruud66 on Thu Jul 16, 2015 4:35 pm; edited 1 time in total
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Chris Meyer



Joined: 19 Sep 2014
Posts: 22

Posted: Wed Jul 15, 2015 11:31 pm    Post subject: Reply with quote

Hi Ruud66,

I have to say sorry. I had asked if you really carefully read my initial post and it was just me who did not! I had written 'Method 2' with the wrong formula. Confused

You wrote:
Quote:
Then I must say that Wim van Dam uses the method of adding the true solar arc in longitude to the MC in longitude.
...
One thing I know for sure with: Van Dam doesn't use method 1 or 2.
I know this because I have the original article in which he published his system of primary progressions for the first time. This was in the Dutch astrological magazine "Spica" somewhere in the 1980's.

As I read your post I was confused and had a really hard time to find out what's going on. Because I had programmed van Dams primary directions for myself and succesfully checked it for its correct results with all references I know of.

Meanwhile 'method 2' is corrected above and here:

Method 2:
2.1. Measure the true solar arc on the ecliptic in longitude.
2.2. Add this true solar arc in longitude to the MC in longitude
2.3. Convert this progressed MC in longitude to right ascension.
2.4. From this progressed MC in right ascension (RAMC) calculate the houses in longitude.

Steps 2.3 and 2.4 are only done because for the calculation of the houses the RAMC is required.

Would you please check 'method 2' again if it's the correct formula for Wim van Dams primary directions?

All I know about his primary directions system I got from his website the astrology software company "Cosmic Patterns" is hosting for him. The articles are last updated in the years 2007 and 2011: http://www.astrosoftware.com/WimVanDamArticles.htm

In his article 'Primary Directions' van Dam shows his primary direction system with example horoscopes for himself and Hitler: http://www.astrosoftware.com/WimPrimaries.htm

There's also a video from the company 'Cosmic Patterns' for their astrology program 'Sirius'. It shows the calculation of a list with Wim van Dam primary directions for the example horoscope of Ben Afflick between time 19:41-21:40: https://www.youtube.com/watch?v=PKOXS4OGEhk

At the bottom of the 'Sirius' Wim van Dam Primary Directions dialogbox you can see in this video it is written: 'Note: Van Dam Primary Directions were developed by Dutch astrologer Wim van Dam. These calculations are provided with his assistance, approval, and exclusive rights. For more information on Wim Van Dam and his astrological techniques you can visit: http://www.astrosoftware.com/WimvanDam.htm'.

'Sirius', 'Solar Fire' and my own little program that is based on 'method 2' are calculating exact the same results for the example primary directions on Wim van Dam website, as well as for Ben Affleck in the video example.

Because of that I was quite sure that Wim van Dams Primary Directions are based on 'method 2'. Hope you now can agree with me about this?
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Ruud66



Joined: 05 Apr 2009
Posts: 46
Location: Amsterdam, Netherlands

Posted: Thu Jul 16, 2015 6:17 pm    Post subject: Reply with quote

Hi Chris,
Apologies accepted. Smile
Yes, I agree now that method 2 (new style) is what Van Dam uses.

Actually we discovered three methods now:
1. add the true solar arc in longitude directly to the RAMC without conversion to arrive at the progressed RAMC
2. add the true solar arc in longitude to the Midheaven to arrive at the progressed Midheaven, all in longitude
3. add the true solar arc, converted to right ascenion, to the RAMC to find the progressed RAMC, all in right ascension

Each of these methods have their own point of view, or philosophy, of what the progressed angles really are about.

Method 1 views the progressed angles as an extension of the idea of the secondary progressions. Secondary progressions are calculated using the idea of "a day for a year". Or in other words: a true solar day in secondary progression is equivalent to and of the same length in time as a true solar year in reality. The flow of time in a true solar day is not measured using a constant clock. The clock is a human invention and has no relevance in astronomy or astrology. If you want to measure the flow of time astronomicaly in the solar day, then the way to go is using Sundial Time.
Something similar applies to the true solar year. Time flow through the true solar year is not measured using the calendar, another human invention, but by observing the Sun in transit through the zodiac.
Thus we arrive at the hour angle of the Sun (in right ascension) in secondary time that is equivalent to the true solar arc (in longitude) in real time: (a part of) a day for (a part of) a year.
This is only true if you see the progressed Midheaven as an extension of this idea of the secondary progressions, because you progress the RAMC with the arc of the secondary progressed Sun, not the transit Sun.
This is the method that I find quite appealing, at least in theory.

Method 2 views the progressed angles as directly attached to the true solar arc and recognises that all astrological methods of working with the natal and progressed horoscopes are 100% ecliptocentric. In the natal horoscope we view positions in the zodiac, disregarding latitude, and in primary progressions, we progress the zodiac positions of planets and points, not their actual location in the sky. A similar argument was put forward by Van Dam aswell. Although he doesn't say this in the original article I talked about earlier, Van Dam's method is actually a variety of Ptolemy's directions on the semi-arc, except that it is not the planets that are directed but the zodiac itself. Ptolemy's primary directions run clockwise, because that is the apparent motion of all points in the sky due to the rotation of the Earth, but if you direct the zodiac clockwise, then the planets seem to move anti-clockwise through this directed zodiac.

Method 3, on the other hand, focuses on the fact that primary directions are a product of the rotation of the Earth. The progressed Midheaven is not seen in connection to the secondary progressions or to zodiacal astrology, but is simply progressed using mundane dynamics.
This is the gist of McCann's article as I understand it. I think this is an equally valid idea as the argument of Van Dam. At this moment I don't know a way to discover which idea is better, at least not in theory. It is quite possible to calculate Van Dam-style primary progressions, but use this third key for finding the progressed RAMC.


Last edited by Ruud66 on Mon Jul 20, 2015 9:46 am; edited 2 times in total
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