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Astro*Dictionary by Michael Erlewine

 

 

 

 

3 articles for "Alcabitus House System"

Alcabitus House System [Astro*Index]

Method of house division named for Alcabitus. The midheaven and ascendant are the 10th and 1st cusps, respectively; the remaining cusps are determined by trisecting the semidiurnal and seminocturnal arcs of the ascendant. Houses are formed by the lunes created by the house circles which pass through these cusps and the north and south points along the Horizon.

See also:
♦ House Cusp ♦ Midheaven ♦ Lune ♦ House Circle ♦ House: Diurnal, Nocturnal ♦ Semi-Arc
Alcabitus House System [Astro*Index]

The midheaven and ascendant are computed as follows:

		   sin(dec) = sin(obl)*sin(LASC)
		   sin(AD)  = tan(ë)*tan(í)
		   SDA = 90° + AD
		   SNA = 90° - AD
		   D   = SDA/3
		   N   = SNA/3
		   RA10 = ST
		   RA11 = ST +  D
		   RA12 = ST + 2D
		   RA1  = ST + 3D
		   RA2  = ST + 3D +  N
		   RA3  = ST + 3D + 2N
		
		Sample:
		   Given that:
		     obl = +23.45°
		     LAT = +37.00°
		     ST  = 07:32:00 = 113.00°
		
		Then:
		   MC  = 111.2768°
		   ASC = 198.8521°
		   dec =  -7.3880°
		   AD  =  -5.6073°
		   SDA =  84.3927°
		   A   =  28.1309°
		   SNA =  95.6073°
		   N   =  31.8691°
		
		RA10 = ST           = 113.0000°
		RA11=  ST +  A      = 141.1309°
		RA12 = ST + 2A      = 169.2618°
		RA1  = ST + 3A      = 197.3927°
		RA2  = ST + 3A +  N = 229.2618°
		RA3  = ST + 3A + 2N = 261.1309°
		
		And,
		
		MC = 10: 111.2768° = CAN 21°16.6'
		     11: 138.6984° = LEO 18°41.9'
		     12: 168.3206° = VIR 18°19.2'
		ASC = 1: 198.8521° = LIB 18°51.1'
		      2: 231.6856° = SCO 21°41.1'
		      3: 261.8532° = SAG 21°51.2'

See also:
♦ House Cusp ♦ Midheaven ♦ Lune ♦ House Circle ♦ House: Diurnal, Nocturnal ♦ Semi-Arc
Alcabitus House System [Prima]

A method of house division named for Alcabitius, an Arab, who is supposed to have lived in the 1st century A.D. Others connect it with an Arabic system that dates from the 10th century at the earliest, and the name of the astrologer-astronomer with the 12th century Alchabitus. This system is the one used in the few remaining examples of ancient Greek horoscopes.

The MC and ASC are respectively the 10th- and 1st- house cusps. The remaining cusps are determined by the trisection of the semidiurnal and seminocturnal arcs of the ascendant. The houses are formed by the lunes created by the true house circles that pass through these cusps and the North and South points of the Horizon. This varies from other quadrant systems, in which the trisection occurs along the ecliptic.

See also:
♦ House Cusp ♦ Midheaven ♦ Lune ♦ House Circle ♦ House: Diurnal, Nocturnal ♦ Semi-Arc

 

Astro*Index Copyright © 1997 Michael Erlewine

 

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