Format for Calculating Lagna (with example) - (courtesy - Prof. E. Ravindran)

Astro Guide Mysore

Lagna / Ascendant Calculation

Input : 1. P.O.B, 2. T.O.B and 3. D.O.B

From Lahiri's Indian Ephemeris (page 144 to 158)

Place Longitude :
Place Lattitude  :

1. I.S.T of birth (AM / PM)                                                     :      h     m    s
2. LMT correction (where the place longitude/lattitude is available    :
    and next column of longitude)                          
3. LMT at P.O.B (AM / PM)     (step 1 + 2)                                   :
4. S.T at 12 Noon on Birth Date, Birth Month and Birth Year          :
    for 82 deg 30 mins (from Table of Asc : Table no. 1 pg 2 & 3)
5. Correction for Birth Year                                                            :
    (From Table of Asc Table no. 11 page 3 & 4)
6. S.T at 12 Noon on Birth Date, Birth Month and Birth Year         :
    for 82 deg and 30 mins (step 4 + 5)
7. Correction for Place of Birth (where the place longitude /            :
     lattitude is available and last column)
8. S.T at 12 Noon on Birth Date, Birth Month and Birth Year         :
    at the Place of Birth        (step 6 + 7)
9. Time interval (TI) between 12 Noon and L.M.T of Birth             :   12 h          00 m    00 s
    (if L.M.T is PM then T.I is L.M.T itself)

                                        (-) step 3                                               :
                             
                                          Time Interval                                       :

10. Correction for T.I (from Table of Asc, Table no. 4 page 5)

                        a) for              hours                                               :

                        b) for              mins                                                :

                            for               h              m     (a+b)                      :
                      
11. The increase in T.I     (step 9 + 10)                                          :
12. S.T at the time of Birth (Please see note below)                        :
 
      From S.T latitude of place, from the Table of Ascendant, to calculate Lagna by interpolation method.

13. For         deg North       Asc                   =
      For         deg North       Asc                   =
      For         variation                                   =

      For          deg North         Mins       Asc  =

14. Aynamsa correction (from Table of Ascendant Pg. 6                :
      for Birth Year  

Note :

a) if T.O.B is AM
    S.T = step 8 - step 11
          if step 8 is < step 11, then
    S.T = (step 8 + 24 hours) - step 11
b) if T.O.B is PM
    S.T = step 8 + step 11
c) if S.T > 24 hours then subtract 24 hours from it to get S.T
d)
     1) for southern latitude, add 12 hours to the S.T as Modified Sidereal Time (MST).
         if M.S.T > 24 hours then subtract 24 hours to get M.S.T
     2) for southern latitude, add 6 signs to the Ascendant.
         If Ascendant is > 12 signs then subtract 12 signs to get the ascendant.


Example Calculation Sheet


Lagna / Ascendant Calculation

Input : 1. P.O.B : Bangalore
           2. T.O.B : 11 hours 54 mins (PM)
           3. D.O.B : 25.09.1970

From Lahiri's Indian Ephemeris (page 144 to 158)

Place Longitude :  77 E 36
Place Lattitude   :  12 N 58

1. I.S.T of birth (AM / PM)                                                             :       11  h    54  m  00 s
2. LMT correction (where the place longitude/lattitude is available    :  (-) 00  h    19 m   36 s
    and next column to longitude)                          
3. LMT at P.O.B (AM / PM)     (step 1 + 2)                                   :       11 h     34 m   24 s  
4. S.T at 12 Noon on Birth Date, Birth Month and Birth Year          :        12 h    14 m   29 s
    for 82 deg 30 mins (from Table of Asc : Table no. 1 pg 2 & 3)
5. Correction for Birth Year                                                            :   (+) 00 h    00 m   11 s
    (From Table of Asc Table no. 11 page 3 & 4)
6. S.T at 12 Noon on Birth Date, Birth Month and Birth Year         :         12 h     14 m   40 s
    for 82 deg and 30 mins (step 4 + 5)
7. Correction for Place of Birth (where the place longitude /            :    (+) 00 h     00 m   02 s
     lattitude is available and last column)
8. S.T at 12 Noon on Birth Date, Birth Month and Birth Year         :          12 h     14 m   42 s
    at the Place of Birth        (step 6 + 7)
9. Time interval (TI) between 12 Noon and L.M.T of Birth             :   12 h          00 m    00 s
    (if L.M.T is PM then T.I is L.M.T itself)

                                        (-) step 3                                               :
                             
                                          Time Interval                                       :     11 h    34 m    24 s 
                                       (since TOB is PM)

10. Correction for T.I (from Table of Asc, Table no. 4 page 5)

                        a) for      11   hours                                               :  (+)   00 h   01 m  48 s

                        b) for              mins                                                :  (+)   00 h  00 m  06 s

                            for               h              m     (a+b)                      :          00 h  01 m  54 s
                      
11. The increase in T.I     (step 9 + 10)                                          :          11 h   36 m  18 s
12. S.T at the time of Birth (Please see note below)                        :          23 h   51 m  00 s
 
      From S.T latitude of place, from the Table of Ascendant, to calculate Lagna by interpolation method.

     (Banglaore place latitude : 12 N 58 can be directly looked up in page 20)

13. For    12 deg North       Asc                   =  2 sign   9 deg   47 mins
      For    13 deg North       Asc                   =  2 sign  10 deg  12 mins
      For         variation                                   =                         25 mins

  
    Calculation to for 58 mins to get to 12 deg and 58 mins (Bangalore)

     1 latitude = 25 mins (from above step 13)
  
     therefore 60 mins = 25 mins
     then        58 mins = 22.30  (or 22 mins 18 secs)  = 22 mins

      For    12 deg North  58 Mins       Asc  =            2 sign 09 deg 47 mins
                                                                      (+)     0 sign 00 deg 22 mins
                                                                       ----------------------------
                                                                                2 sign 10 deg  09 mins

14. Aynamsa correction (from Table of Ascendant Pg. 6                :        2 sign 10 deg 09 mins
      for Birth Year  1970                                                                  (-)   0 sign  0 deg  27 mins
                                                                                                       ---------------------------
                                                                                                             2 sign  09 deg 42 mins

The Ascendant falls in Gemini at 9 degrees and 42 mins

Note :

a) if T.O.B is AM
    S.T = step 8 - step 11
          if step 8 is < step 11, then
    S.T = (step 8 + 24 hours) - step 11
b) if T.O.B is PM
    S.T = step 8 + step 11
c) if S.T > 24 hours then subtract 24 hours from it to get S.T
d)
     1) for southern latitude, add 12 hours to the S.T as Modified Sidereal Time (MST).
         if M.S.T > 24 hours then subtract 24 hours to get M.S.T
     2) for southern latitude, add 6 signs to the Ascendant.
         If Ascendant is > 12 signs then subtract 12 signs to get the ascendant.

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Author:

Sheshachalam Iyengar
Jyotish Visharad : iyengarastro@gmail.com
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