Tropical to Sidereal Conversion?

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Sam Hayden
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Tropical to Sidereal Conversion?

Post by Sam Hayden » Sun Sep 24, 2017 10:37 pm

Is there an accurate way to make an adjustment in a Tropical astrology software to displaying a Sidereal chart by changing the date on the Tropical chart to reflect the difference in degrees on the Sidereal chart?

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Jim Eshelman
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Re: Tropical to Sidereal Conversion?

Post by Jim Eshelman » Sun Sep 24, 2017 11:34 pm

Sam Hayden wrote:
Sun Sep 24, 2017 10:37 pm
Is there an accurate way to make an adjustment in a Tropical astrology software to displaying a Sidereal chart by changing the date on the Tropical chart to reflect the difference in degrees on the Sidereal chart?
No, changing the date won't do it. For example, all the planets don't move the same distance in 24 days.

Most astrology software simply gives you a choice whether to calculate the chart in Sidereal or Tropical zodiac,
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TheScales_BothWays
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Re: Tropical to Sidereal Conversion?

Post by TheScales_BothWays » Mon Sep 25, 2017 8:52 am

Hey Sam, welcome to the forums! Hope you'll have a great journey of learning Sidereal Astrology with us here. 😊

Some astrology programs can convert Tropical charts to sidereal ones in your preferred ayanamsa with one or two clicks, while some may require you to recalculate them. Just switch your zodiac settings to sidereal and recreate the chart. ;)

Changing the date wouldn't be accurate—as Jim said above, all the planets don't move the same, this is worse if they're in retrograde, moreover—and even for the Sun, changing the date may not convert the Tropical Sun's longitude exactly into sidereal by the minute and second, sometimes even degree.

I'm not sure which astro program you're using, but if the differences in degrees between the tropical and sidereal zodiacs is what you're trying to determine, then here's a relatively simple, not-so-complicated method: first, set to show the Vernal Point (VP) to show up in your charts. Create a sidereal chart for the current moment (or a more "standard" date like 1st January 2000/2010) with your preferred ayanamsa, and then you can subtract the value of the Vernal point from the 1st point of sidereal Aries (which is 0°Aries). This forum is dedicated to using the Fagan-Allen zodiac, and using that ayanamsa, we get the Vernal point at 5°00' Pisces, showing that the Fagan-Allen zodiac is currently about 25°00 from the Tropical zodiac to the nearest minute. To get the value to the nearest second, I'm sure there are options in your program to show the VP to the second, probably named as "reports" or something similar, and subtract the value shown from 0°Aries. ;)

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Re: Tropical to Sidereal Conversion?

Post by mikestar13 » Mon Sep 25, 2017 12:05 pm

Welcome Sam. A good or even fair Astrology program will give the option to calculate sidereal zodiac chart. But if you have an inexpensive, tropical zodiac only program, you should visit astro.com, where you can calculate charts free with a lot of options. Go to their extended chart section and follow the instructions to cast a natal chart. For the zodiac option, chose Sidereal, Fagan/Bradley, Geocentric. For house system, choose Campanus, which is consensus choice of western sidereal astrologers such as we folks here on Solunars.
Time matters

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Re: Tropical to Sidereal Conversion?

Post by Sam Hayden » Tue Sep 26, 2017 7:04 pm

Thank you, I didn't think it could be that simple but I had to ask. I have primarily been using Time Passages Pro on iPhone for studying Tropical astrology but it doesn't have an options for Sidereal, Fagan/Bradley, Geocentric. I purchased a copy of iPhermis to view Sidereal charts and I found it is a great piece of software but lacks the detailed information on birth charts and the current transits which I am used to having access to in TPP. I just contacted Astrograph to see if they will add the Sidereal option to the TPP but until then it looks like I'll have to spend a little more time doing things the old fashion way...which is really what I should be doing anyway.

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Re: Tropical to Sidereal Conversion?

Post by Jupiter Sets at Dawn » Tue Sep 26, 2017 8:45 pm

Sam Hayden wrote:
Tue Sep 26, 2017 7:04 pm
it looks like I'll have to spend a little more time doing things the old fashion way...which is really what I should be doing anyway.
If you use astro.com once you have the chart cast look on the left hand side for the link to "Additional tables (PDF)."
That pdf gives the ayanamsa for the date of the chart, the longitude to the second, the latitude and declination and the aspectarian in a more readable format.

BTW if you want the SQ (Solar Return progressions,) just set up a "birth chart" for the date, place and time of the solar return and use the secondary progressions.
Don't use astro.com's mundoscope. It's not the same thing we use. But the Astro maps (under Special Charts) are the same.

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Re: Tropical to Sidereal Conversion?

Post by Jim Eshelman » Thu Sep 06, 2018 5:50 pm

Sam, happy birthday!
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Lance
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Re: Tropical to Sidereal Conversion?

Post by Lance » Fri Sep 07, 2018 9:50 am

Sam,

I use iPhemeris with Jim's interpretations listed here. In fact, if you want interpretations, you'll probably want to start using the ones here or those given by other specifically sidereal astrologers. They're less theoretically derived and more observationally derived.

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Re: Tropical to Sidereal Conversion?

Post by Mike » Wed Sep 12, 2018 7:35 pm

Hey Sam!

Personally, I love iPhemeris for everything except return charts (it seems to be sloppy with its time calculations).
Its transit calendar is really useful, IMO. I think it's the best thing out there that isn't Solar Fire.

I wouldn't worry about getting interpretations from the software, honestly - I would just use it as a calculational tool. Otherwise, you get stuck relying on the software to tell you what you're looking at.

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