posted February 26, 2008 02:07 PM              

This is the method I was given over at Astro.com's forum:

quote:

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In this method, we correlate movement of the sun in celestial longitude (tropical zodiacal position) with movement of the RAMC in right ascension. In other words, we equate a tropical year and a sidereal day.

Procedure:

1. Find the celestial longitude of the sun for the transit time.

2. Determine how far it has moved relative to the celestial longitude of the natal sun. Keep track of cycles (ie the number of solar returns since birth).

3. Determine the RAMC of the natal chart. This is listed on some chart forms, or you can use trig to convert the MC to RAMC, or you can convert the Local Sidereal Time (LST, usually listed on chart forms) to RAMC by multiplying it by 15 (ie converting time to degrees).

4. Add the number of cycles found in #2 to the radix as sidereal days (returns of the RAMC to its natal position). Add the remaining difference in degrees found in #2 as well. You now have the RAMC of the progressed chart, as well as the date.

5. Convert the RAMC to LST by dividing by 15 (ie converting degrees to time)

6. Now we want to determine the UT of the progressed chart. The chart should be calculated for where the native was at the progressed time. Unless you know s/he was elsewhere, it's generally good enough to use the birth location. Convert the geographical longitude of the location to time by dividing by 15.

7. If the geo longitude is west, add the resulting value to the LST; if east, subtract it. You now have the sidereal time at Greenwich (GST). Using an ephemeris or other method, find the difference between the GST and the GST at 0h UT (be sure to keep proper track of the date). Divide the result by 1.00273790935 to convert the interval from sidereal time to universal time.

8. If you used 0h to determine the difference, you now have the UT of the progressed chart. Convert to the timezone of the radix to get local time, and use a program to calculate the progressed chart based on that local time, and the location you decided to use.

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