speculum

CelestialStarFire · Post by **CelestialStarFire** » Mon Aug 27, 2012 8:35 pm

I need to find the speculum for a natal chart, do you know how I can find this feature in kairon? Thanks

mehemptah · Post by **mehemptah** » Sat Sep 01, 2012 6:40 pm

can you be more specific?

CelestialStarFire · Post by **CelestialStarFire** » Sat Sep 01, 2012 7:44 pm

The Speculum (From the common Latin word for Mirror) is simply a list of the Sidereal Times passing over the Midheaven, when the planets or stars rise, culminate,set and anti-culminate. It is an expression of the diurnal rotation of the sphere. That is, the rotation of the earth on its axis. When a planet has an RAMC for crossing an angle,that is the same or nearly the same as that of the moment, the planet is on the reference angle. A planet is on the MC, when its Right Ascension is the same as the local Sidereal time. Likewise, when the the Right Ascension of a planet has exactly 12 hrs difference from the local Sidereal Time, that planet is on the lower meridian or IC. The RAMC for a plant or star rising or setting will depend on the declination of the body and the latitude of the location. The difference between rising/setting and MC/IC is exactly 90 degrees (6 hours of Sidereal time) only at the exact equator. This difference is knows as the semi-arch. As one moves either North or South of the geographic equator, the semi-arch will vary as the ascensional difference (AD) this is given by the simple trig expression sin AD= tan d x tan g. Where d is the declination of the body, and g the latitude of the observer. Then Semi-arc = 90 + AD/15=HMS. If the AD is positive (+), it is added to 90 degrees, but if negative (-), it is subtracted from 90 degrees. The RA of a body represents the Local Sidereal Time for its culmination. As a body must first rise before it can culminate RAMC rising = RA - semi-arc. Likewise, a planet must set before it can anti-culminate. therefore the RAMC setting = RA + semi-arc. Together, these four values, make up the list, known as the speculum.

mehemptah · Post by **mehemptah** » Wed Sep 05, 2012 9:10 pm

ok, well, you can't find that in Kairon (yet)

but thank you for the detailled description!

vjs · Post by **vjs** » Fri Sep 07, 2012 3:32 pm

Hi CelestialStarFire,

try following astro software Morinus on Mac, http://astro-morinus.blogspot.com/ . Speculum is part of this software.

Regards

Vaclav