This software is licensed under the CC-GNU GPL.
Download Aldebaran for Windows, version 1.2 build 18 (includes source)
A while ago, I started exploring western sidereal astrology--i.e. astrology as practiced up until about the middle ages when people decided to start using the equinox points instead of the stars to mark the zodiac signs. A lack of good software made this surprisingly difficult: the techniques used by the ancient Egyptians and Babylonians, as well as modern western sidereal astrologers like Cyril Fagan, are different from those used by either tropical astrologers or vedic astrologers, and although there are many programs with a sidereal "option", such as Astrolog, there didn't seem to be much out there that natively understood western sidereal techniques such as cardinal ingresses and solar/lunar returns.
I grew tired of calculating things manually, so I wrote a piece of software to do it for me: Aldebaran, named after the prime fiducial star of the Babylonians. It's freeware (open-source actually), uses the Swiss Ephemeris for as great an accuracy as is possible, and was designed from the ground up for western sidereal measurements, calculations, and techniques. The design has been kept simple, foregoing recent "innovations" such as houses and minor aspects (even the trine). I hope you find it useful!
Note: Command-line switches override the default settings in Aldebaran.ini.
-c[CALENDAR] Specify calendar system. Where [CALENDAR] is put: greg Gregorian (default) jul Julian -z[ZODIAC] Specify ayanamsa. Where [ZODIAC] is put: faganbradley Fagan-Bradley lahiri Lahiri -nosavedefs Disable saving of default options; otherwise radical chart data, ayanamsa, and calendar will be saved as the default and loaded on startup.
If you try to calculate the previous solar or lunar return, and the next return is less than about two and a half minutes in the future, that future return will be calculated instead. This is an artifact of the way returns are calculated.
Do not enter months or days with a leading zero; the effect will be the same as if you had decremented the value from one. This is necessary for the increment-decrement carry functions to work (eg, if the date is 04-01 and you highlight the day and press down, the date will be changed to 03-31). Leading zeros in the hour, minute, and second fields can be used without issue.
The date entry boxes do not accept any entry except the numbers, '-', '+', and '.'. Despite the fact that the edits will accept them, do not enter these characters anyway. The results are undefined. Exception: negative numbers may be used in the year box; note that 0 is 1BC, -11 is 12BC, etc.
Proper speed for 'secondary' (day-for-a-year) progression is one sidereal day for one sidereal year. That is, advance the radical chart 0.997269560167 Julian days for every 365.242197708 Julian days that have actually passed. Those of you who have read Fagan's Primer of Sidereal Astrology, that's what the bija correction is about: converting mean solar years to sidereal years.
Max. positional error (without ephemeris files): 0.1 arcsec (3 arcsec for Moon)
Max. positional error (with ephemeris files): 0.001 arcsec
Max. additional error for Solar returns and cardinal ingresses: 0.037 arcsec [<0.87 second of time]
Max. additional error for Lunar returns: 0.45 arcsec [<0.87 second of time]
Max. additional error for Lunar cardinal ingresses: 0.72 arcsec [<1.4 second of time]
Note #1: for best possible accuracy, download the ephemeris files from the Swiss Ephemeris site and place them in a subdirectory called 'Ephemerides' in your Aldebaran directory. This will also make calculation slightly faster.
Note #2: Although radical and transit chart dates can only be specified to 1-second precision, all programmatically-derived charts are calculated to sub-second precision.
This software is licensed under the CC-GNU GPL.