Vedic Astrology: Calculation of Ascendant or Lagna
Ascendant is the point of ecliptic on the eastern horizon at a specific time.
Let us calculate the ascendant step by step
To
calculate this point tropical longitude of sun is required.
Step
1:
Calculate the tropical longitudes of the sun.
Tropical longitude of
sun = Nirayana longitudes + Ayanamsha.
Step
2:
Calculate the difference between the birth time (LMT) and a sunrise on a given
day. This is called as Ishta kala.
Step
3:
Consider the sign in which the sun is in and the degrees he has traversed in
that sign. ( Note: Consider the tropical longitudes of the Sun. )
Step
4:
Calculate by direct proportion the expired portion of the sign the sun is in at
the time of sunrise.
Step
5:
Calculate the unexpired portion by deducting the expired portion of the sign as
calculated in the fourth step.
Step
6:
The duration as calculated in the 5th step
should be deducted from the Ista Kala. If duration of the sign is
greater than Ista Kala then ignore this step. Since the sign itself is
the rising sign ignore step 7 and go to step 8.
Step
7:
Deduct the duration of each successive signs up to the sign you may not be able
to deduct anymore. This will happen when the duration of the sign is greater
than the remainder. This is the rising sign at the time of the birth. (The
duration of the sign varies from place to place. So to determine the sign
duration we have to calculate the Rasimanas as given in another post.
Refer the Rasimanas for Pune and Hong Kong in Annex A)
Step
8:
The remainder as calculated in step 6 or 7 * 30 degrees / the duration of the
sign.
Step
9:
The degrees thus determined are the tropical longitudes of the ascendant.
Deduct the ayanamsha for the year and the result is the nirayan
longitudes of the ascendant.
Example:
Particulars
|
Pune
|
Hong Kong
|
Tropical longitude of sun (A)
|
3/9/44/00
|
3/9/44/00
|
(2/15/51/35 + 23/52/25)
|
(2/15/51/35 + 23/52/25)
|
|
Birth Time - Sunrise (B) (Ista kala)
|
11/58/28
|
14/47/24
|
Sign of the sun (C)
|
Cancer
|
Cancer
|
Degrees of the sun in Cancer (D)
|
9 deg 44 min
|
9 deg 44 min
|
Expired portion in cancer (E)
|
43 min 43 sec
|
44 min 4 sec
|
(D) * (rasimanas) / 30
|
||
Un-expired portion in cancer (F)
|
91 min 3 sec
|
91 min 46 sec
|
(rasimanas) - (E)
|
||
Ista Kala
|
11/58/28
|
14/47/24
|
Less Duration of cancer
|
91 min 3 sec
|
91 min 46 sec
|
Balance
|
10/27/25
|
13/15/38
|
Less Duration of leo
|
2/14/10
|
2/16/43
|
Balance
|
8/13/15
|
10/58/55
|
Less Duration of Virgo
|
2/9/41
|
2/12/52
|
Balance
|
6/3/34
|
8/46/03
|
Less Duration of Libra
|
2/9/41
|
2/12/52
|
Balance
|
3/53/53
|
6/33/11
|
Less Duration of Scorpio
|
2/14/10
|
2/16/43
|
Balance
|
1/39/43
|
4/16/28
|
Less Duration of Sagittarius
|
2/14/46
|
2/15/50
|
Balance
|
*
|
2/00/38
|
Less Duration of Capricorn
|
2/1/38
|
|
Balance
|
*
|
*Now
we are in a situation where we cannot deduct the rasimanas from the ista
kala. This indicates the tropical sign rising at the horizon. Thus tropical
Sagittarius is rising in Pune while tropical Capricorn is rising in Hong Kong.
Tropical sign rising
|
Sagittarius
|
Capricorn
|
Duration of the sign
|
2/14/46
|
2/1/38
|
Balance left
|
1/39/43
|
4/16/28
|
(Balance) * 30 / (2/14/46)
|
22/11/51
|
29/45/12
|
Less Ayanamsa on July 1, 2001
|
23/52/25
|
23/52/25
|
Nirayana rising sign is
|
Scorpio
|
Capricorn
|
Longitudes in the sign
|
28/19/26
|
5/52/47
|
Note
: It may be noted that the correct ascendant
at Pune as per modern trigonometric calculation is 29 deg 46 mins of Scorpio
instead of 28/19/26. Similarly the correct ascendant at Hong Kong as per modern
trigonometric calculation is 6/42/00 of Capricorn instead of 5/52/47. The
difference can be safely ignored at this stage.
Annex A
|
||||||||
Sr.no
|
Sign
|
Rising period
|
+/-
|
Charakhandas at 18N32
|
Charakhandas at 22N20
|
Rasimanas or duration
|
Rasimanas or duration
|
|
at 0 Lat.
|
of signs at 18N32
|
of signs at 18N32
|
||||||
1
|
Aries
|
111 min. 36 sec
|
-
|
18 minutes 5 seconds
|
21 minutes 16 seconds
|
93 minutes 05 seconds
|
90 minutes 20 seconds
|
|
2
|
Taurus
|
119 min 40 sec
|
-
|
14 minutes 30 seconds
|
17 minutes 3 seconds
|
105 minutes 10 seconds
|
102 minutes 37 seconds
|
|
3
|
Gemini
|
128 min 44 sec
|
-
|
6 minutes 2 seconds
|
7 minutes 6 seconds
|
122 minutes 42 seconds
|
121 minutes 38 seconds
|
|
4
|
Cancer
|
128 min 44 sec
|
+
|
6 minutes 2 seconds
|
7 minutes 6 seconds
|
134 minutes 46 seconds
|
135 minutes 50 seconds
|
|
5
|
Leo
|
119 min 40 sec
|
+
|
14 minutes 30 seconds
|
17 minutes 3 seconds
|
134 minutes 10 seconds
|
136 minutes 43 seconds
|
|
6
|
Virgo
|
111 min. 36 sec
|
+
|
18 minutes 5 seconds
|
21 minutes 16 seconds
|
129 minutes 41 seconds
|
132 minutes 52 seconds
|
|
7
|
Libra
|
111 min. 36 sec
|
+
|
18 minutes 5 seconds
|
21 minutes 16 seconds
|
129 minutes 41 seconds
|
132 minutes 52 seconds
|
|
8
|
Scorpio
|
119 min 40 sec
|
+
|
14 minutes 30 seconds
|
17 minutes 3 seconds
|
134 minutes 10 seconds
|
136 minutes 43 seconds
|
|
9
|
Sagittarius
|
128 min 44 sec
|
+
|
6 minutes 2 seconds
|
7 minutes 6 seconds
|
134 minutes 46 seconds
|
135 minutes 50 seconds
|
|
10
|
Capricorn
|
128 min 44 sec
|
-
|
6 minutes 2 seconds
|
7 minutes 6 seconds
|
122 minutes 42 seconds
|
121 minutes 38 seconds
|
|
11
|
Aquarius
|
119 min 40 sec
|
-
|
14 minutes 30 seconds
|
17 minutes 3 seconds
|
105 minutes 10 seconds
|
102 minutes 37 seconds
|
|
12
|
Pisces
|
111 min. 36 sec
|
-
|
18 minutes 5 seconds
|
21 minutes 16 seconds
|
93 minutes 05 seconds
|
90 minutes 20 seconds
|
Activity: Calculate
the position of ascendant at Singapore on 1 st July 2001 18:00(IST) also
calculate sunrise and sunset of Singapore on the same day.
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