20
Hi Harold,

I apologize for my absence, but the Skyscript forum has some imperfections...

In addition to changing the content of the texts if some mathematical notation is used, most of the time I do not receive notifications of reply messages on the threads I participate in. So I had not noticed your subsequent interventions

It's very strange that you were unable to download Makransky's PDFs from my OneDrive. When I have provided some links in the past, there have generally been no problems. At least using Chrome and Edge or another browser and not your OneDrive. By the way: is there anyone who followed the thread and tried to download them?

However, if you have found them, that's fine :-)

Roberto

21
Hi Harold,

As for the link you reported, as I understood from the example shown, ZET also correctly depicts the three-dimensional representation of the Placidean domification. That is, it is not based on the in mundo path of the Sun and then projecting onto this (somehow) the position of the planets (which would be an approximate representation) but it seems that for each celestial object it uses its true Placidean Mundane Position -PMP-

Other programs that make use of three-dimensional techniques, use instead the same algorithms used for the Campanus and Regiomontanus domifications, which are "projection systems". And the Placidus is not...

Thank you,
Roberto

22
I has been too hasty to comment on ZET's three-dimensional graphs when they are used in Placidus house system.

The problem that arises with Placidus derives from the fact that each planet has its own diurnal arc with celestial latitude other than zero (the orbits do not lie on the ecliptic) and that the cusps of the houses are calculated with an exquisitely temporal criterion NOT valid in space of the Celestial Sphere for the other planets.

Wishing to do so, it would be necessary to have many Placidean house systems in space, and precisely one for each planet. And even succeeding to do that with illegible graphics, by doing this, a rigorous angular comparison IN MUNDO in the metric of space would be impossible.

In other words, we have only two possibilities:
-Place the planets where they really are in the celestial sphere graphics, and then the PMP references are approximated
-Place the planets in the graphics of the Celestial Sphere with their PMP positions referred to the Placidean domification of the path of the Sun, but then the Equatorial and Ecliptic planetary coordinates are approximated.

All this can be summarized with a very simple observation: the Placidus house system is a purely temporal system, and not a spatial one. With it, any technique that represents it in a three-dimensional space is meant to be just an approximate representation of reality.

The good news is that, at least up to about 10° celestial latitude, the approximation is good :-)

Roberto

To Roberto

23
Hello Roberto-When I included astrozet link in my last post I thought it was based on a Regio system.(I didnt read text complete)CMP and ZD was really my interest.But now I can use ZET for the PMP as well.I recently calculated ZD for Saturn from Prince Charles chart(makransky page 36-38) where the position of S seems to be where Saturn is found.Makransky uses 3 triangles in his formula.I understood how these 3 were drawn since the sides are all common great circles (and resulting angles) Although I am not sure what the house circle is.I didnt know planets had house circles.I know that it moves on its diurnal arc.But this circle seems different.I searched through Makranskys text but I didnt see this circle explained.Thank You once again for your formula -After doing saturn from the nadir I had to take CMP (apv) from 90 to get ZD As positions shows in Morinus. and you explained when above the horizon the 90 degree distance can be plainly seen.I am glad you explained how this point is found-I wish you the best-Harold