Skyscript Astrology Forum

leywand wrote:I tried to use "Planetary, Lunar, and Stellar Visibility 3" freeware from
www.alcyone.de

Nice program, but as visibility can be defined so or so, I have no idea, if the program is useful for astrology.

It is useful because it lists which planets are visible, which in heliacal rising and so.
At least Ptolemy would love it

I meant that there are no agreed upon definitions of visibility in astronomy (as far as I know) , so no one knows if Ptolemy had agreed with the programs? results. I somewhere read that the different parameters in use (u can edit these in the program) would amount to a difference in the heliacal rising of sirius of about 3-4 days. So just a caveat if u want to be very exact... .
And after all if it?s cloudy, no one can determine the helical rising of a star as it just can?t be seen.

I somewhere read that the different parameters in use (u can edit these in the program) would amount to a difference in the heliacal rising of sirius of about 3-4 days. So just a caveat if u want to be very exact...

Really? I find that surprising. I would have thought one could have pinned down a heliacal rising star or planet to a day quite accurately. Brady certainly thinks she has this sorted out on StarLight for fixed stars.

leywand wrote:I meant that there are no agreed upon definitions of visibility in astronomy (as far as I know) , so no one knows if Ptolemy had agreed with the programs? results.

Well, maybe Ptolemy would prefer to calculate planetary visibility of a planet by hand, but we should do the same?
Heliacal phases are very important in Tetrabiblos because the very quality of the planet - if hot, moist, dry or cold-depends on it.
Then at least this software let us the possibility to know which phases planets in a easy way.

Here?s a quote from the program documentation:

Sources of Computations and Cautions concerning Accuracy.

Visibility phenomena have been computed since antiquity, but are still among the most uncertain astronomical phenomena to calculate accurately. First, there are the obstacles of weather, atmospheric transparency, and ambient light, which are difficult or impossible to control by any calculation. But even assuming optimal observing conditions, there remains the problem of the absence of an adequate body of reliable observations of the phenomena for comparison with calculation...etc.....

The whole text can be found here

http://www.alcyone.de/PVis/documentation/index.html

another quote:

Since they are of historical interest and may prove useful, we also give Ptolemy's values of the arcus visionis. These differ in the Almagest and in the later Handy Tables and Planetary Hypotheses, which are probably based upon later observations and appear to be somewhat better.
Phenomenon Almagest HT & PH
Saturn F & L 11? 13?
Jupiter F & L 10 9
Mars F & L 11.5 14.5
Venus EF & ML 5 7
Venus MF & EL 5 5
Mercury All 10 12

I don?t know if Ptolemy gave values for fixed stars also...

You can get a free report from Brady?s website. In her report for my natal she chose a quite small and insignificant star (I forgot) as helical rising star. Checking with an astronomy program I found several others that would qualify as helical rising star. I wondered why she chose this one ?

I think her approach is debatable, but she certainly invested more work and time than I did.

A similar problem seems to be to determine a nighttime chart. I always thought that as soon as the sun is below the DC and is in house 6 (i.e below the horizon), it?s a nighttime chart. But I learned otherwise here:

Obama was born just after sunset, but it was still daylight, so we can consider his horoscope diurnal.

DC is 12 leo, sun is 18 leo , 6 ? in house 6...hmm??

from:

http://gryphonastrology.com/blog/2008/0 ... /#comments

You can get a free report from Brady?s website. In her report for my natal she chose a quite small and insignificant star (I forgot) as helical rising star. Checking with an astronomy program I found several others that would qualify as helical rising star. I wondered why she chose this one ?

I have a lot of respect for what Brady has done on fixed stars. Still I do have certain reservations about her approach. One of them is as you suggest her quite subjective use of certain stars at the expense of traditionally important ones.

I plan to start a thread soon where I will compare Brady's approach on parans to Anonymous of 379 and point out some important divergences. She claims this is her main traditional source in all her writings. However, in many respects she has altered the approach outlined by Anonymous of 379 without making that explicit in her books.

leywand wrote:
A similar problem seems to be to determine a nighttime chart. I always thought that as soon as the sun is below the DC and is in house 6 (i.e below the horizon), it?s a nighttime chart. But I learned otherwise here:

Obama was born just after sunset, but it was still daylight, so we can consider his horoscope diurnal.

DC is 12 leo, sun is 18 leo , 6 ? in house 6...hmm??

from:

http://gryphonastrology.com/blog/2008/0 ... /#comments

I showed Obama chart to my friend in CieloeTerra because to me too it was difficult understand if it was a night or a day chart, because even if the Sun is below the horizon, still it was not completely set and there was light in sky.

To make short a long story, my friend checked with an astronomical software if some planets were visible in the sky, because when the Sun is in the sky there is no other light.
Well Jupiter was visible, so this makes - at lest for Bezza group- a night chart.

Thanks Leywand

Fascinating! This had never occured to me before.

I wish to clarify, though, that a chart can be diurnal even though the Sun is quite a bit below the horizon. For me, civil twilight (Sun less than 6 degrees under the horizon) is daylight. Some astrologers are even more lenient, and include nautical twilight (6-12 degrees below the horizon) as daytime. (Nina Gryphon)

I am wondering which traditional authorities Gryphon is relying on here? The issue of whether a chart is nocturnal or diurnal is crucial to hellenistic and medieval astrologers. Can we assume this is the approach they adopted? This seems a very important question to discuss specifically. I have therefore created a new thread on this issue: 'Is the Chart Diurnal or Nocturnal?'

http://skyscript.co.uk/forums/viewtopic.php?t=3688

To make short a long story, my friend checked with an astronomical software if some planets were visible in the sky, because when the Sun is in the sky there is no other light.

Surely, the Moon and Venus(?) are visible sometimes?

As for me I?m not convinced. I?ll stick to the "simple" approach. Nighttime chart is when sun is in house 6 below the DC, because only this approach is consistent with the planetary hours, measured from sunrise to sunset (and vice versa). Right after sunset the first hour of the night begins -> nightchart.

I didn?t come across any traditional sources speaking of civil or nautical twilight in determining a nightchart.

Hi Leywand,

Nonetheless I am grateful to you for raising this. Any chance you could post your reply in the new thread focusing on this issue specifically? I am concerned this thread has gone all over the place so many people might not get this far in and notice this!

Thanks

Mark