Astro-calculator

The Astro-calculator is designed for astronomical and astrological calculations and conversions related to various coordinate systems. It is primarily useful for traditional astrologers.

Interface

The top row of the calculator shows the data of the current dial. This data will be used in the calculations. The area located below the Arguments checkbox is used to enter initial values. If the checkbox is checked, these are ecliptic coordinate values; if not, they are equatorial. You will need to enter the pole of the significator if you want to perform specific calculations for the Regiomontanus house system (more on this later).

Below this, the Geographical Latitude and Right Ascension of the MC (RAMC) corresponding to the current data are displayed.

Let’s say you have entered the longitude and latitude arguments for a specific point. You will immediately see the following calculated parameters:

• Which quadrant the point falls into;
• Its right ascension and declination (if equatorial arguments were used, these will be longitude and latitude);
• Oblique ascension and descension;
• Ascensional difference;
• Upper and lower meridian distance;
• Diurnal and nocturnal semi-arc;
• Diurnal and nocturnal seasonal hour;
• Hour angle (hour distance);
• Mundane position in the Placidus system;
• Whether the point is in Cazimi. The orb for Cazimi is determined by the corresponding settings — Settings > General Preferences > Aphetical Calculations > Distances from the Sun. There you can also choose whether to consider latitude in the calculations.

You can also calculate an ecliptic point based on right ascension, oblique ascension, or oblique descension. This is done in a separate area at the bottom left of the window.

For those using the Regiomontanus system, the following are also calculated:

• Zenith distance;
• Ascensional difference under its own pole;
• Pole;
• Oblique ascension (descension) under its own pole;
• Oblique ascension (descension) under the pole of the significator. In this case, you must define the pole of the significator in the arguments.

Clicking on Cusps opens the table of house circles according to Regiomontanus. Here we see the pole value and oblique ascension (descension) under its own pole for each cusp.

The columns marked with parentheses (-5) show the same values but for house circle positions shifted by -5 mundane degrees. This is useful when we want to precisely determine whether an object placed before a cusp should be considered in the next house according to the 5-degree rule, taking spherical geometry into account.

If you want to use the arguments of an object already present on the chart, simply left-click on it. Its coordinates will automatically populate the arguments, and all parameters will be recalculated instantly. If any abbreviations are unclear to you, hover your mouse cursor over those values to see a helpful tooltip.

Example

Here’s how to use it. Let’s take this chart as an example (04.04.1972 22:00 Moscow):

Let’s look at Venus, which is located just before the 8th house cusp in the Regiomontanus system. We can see that the distance between Venus and the 8th house cusp is 6° 35’ (looking at the aspect table). But we need to determine whether Venus is in the 7th house or has already moved into the 8th according to the 5-degree rule. Moreover, these must be mundane degrees. To do this, we need to compare the mundane position of Venus with the mundane position of the house circle corresponding to the 8th house, but shifted by 5 mundane degrees.

Now we click on Venus, and its coordinates are automatically entered into the arguments. Instantly, all the calculator data updates. Looking at the house circles table, the pole of the shifted 8th house circle is 53° 5’, so we enter this value into the Pole of the significator cell. We press Enter, and we see the value we need: the oblique descension under the pole of the significator is 93° 9’. All that’s left is to compare it with the corresponding value of the house circle from the table. The oblique descension of the shifted 8th house circle is 90° 48’. This means that Venus has crossed the mundane position of the shifted 8th house circle, and in this case, we can say that it already belongs to the 8th house.

To hide the cusps table, click on Cusps again.