Manual Calculation of Ascendant
Manual Calculation of Ascendant
In today’s time it is very easy to find out the lagna or ascendant and longitudes of the planets from the computers. It will be good if we know to calculate manually. There are two methods in calculating the ascendant manually. One is traditional method and other is the modern method using Table of ascendants.
In this section we will deal with the second method of calculating the ascendant. You require a book called ‘Table of Ascendants on Nirayana basis’ by N.C. Lahiri to calculate the ascendant. This will be available in all the leading book stores.
Date of Birth
Time of Birth
Place of Birth
Calculate Local Mean Time (LMT) Correction
Step 1- Find out the longitude of Standard meridian (S.M) for the country or zone. If you know the timezone of the country, you can calculate the S.M. It will be readily available in Ephemeris book.
Step 2 – Note down the longitude of the place for which ascendant is calculated
Step 3. Find out the difference between longitude of S.M to longitude of place of birth
Step 4. Multiply the difference by 4 (as 1° is equal to 4 minutes and 1’ is equal to 4 seconds). The product will give you LMT correction
Step 5 – Note down whether the longitude of the place of birth is towards east or west of the standard meridian. Prefix the sign ‘+’ or ‘-’ to the LMT correction if it is towards east or west of the S.M respectively.
Step 6 – Apply the LMT correction to the standard time to get the LMT.
Calculate Sidereal time
Step 1 – Note down the sidereal time at 12h noon local mean time for 82°30’E longitude from Page No. 2 & 3 of Table of Ascendants (82°30’ is the longitude of standard meridian for India)
Step 2 – Note down the correction for the given year from the table II on page 3 and 4 of Table of ascendants and apply to sidereal time in Step 1
Step 3 – Note the correction for the birthplace from table III on page 5 and 100 to 107 of the book.For non-Indian cities refer page 109 to 111
Step 4 – We get Sidereal time for the given date, year and place by applying the correction for the year (step 2) and correction for the place (step 3)). Prefix the sign ‘+’ or ‘-’ accordingly. Note that the time is for the local noon (12hrs). Let us consider this figure as ‘A’
Step 5 – Convert the birth time of epoch into LMT by applying LMT correction. (Step 1 to 6 of first section)
Note down the LMT of birth. You will also get this figure from Table of ascendants page no. 100.
Step 6 – As the sidereal time obtained in step 4 is for 12h local noon, we have to now find out the difference between LMT to the 12h noon. This is called as Time Interval (T.I.) between the local mean noon and the LMT of the given moment. If the LMT of the birth time is before noon, subtract it from 12:00 hrs. If it is in the afternoon, then the LMT itself becomes TIme interval.
Step 7 – Now we have to work out the correction for hours and minutes of the time interval. The time interval to be increased by applying the correction given in table IV . Let us consider this figure as ‘B’
Step 8 – In case of before noon (AM) birth or LMT, the increased time interval (B) from step 7 is subtracted from the corrected sidereal time in step 10 (A) and if A<b, class=”hiddenSpellError” data-mce-bogus=”1″ pre=”24 ” <span=”” 24=”” add=”” then=””>hrs to A and then subtract. In case of afternoon (PM) birth, A and B should be added. The resulting figure is the Sidereal time of birth or the given moment.
Calculation of Longitude of the Ascendant
Step 1 – Find out the longitude of the lagna for the given latitude from the Table of ascendants from page no. 9 to 79 for the sidereal time obtained from step 8 of previous section. If the exact time is not shown, then take the two nearest longitudes of either side and subtract from higher to lower. It will give the variation in terms of 4 minutes.
Step 2 – Subtract sidereal time from nearest higher sidereal time of the table and convert it into seconds
Step 3 – Find out the variation for the resulting time by multiplying the figure of step 1 with step 2 and divide the figure by 240. (since the difference in time is 4 minutes i.e. 4*60 seconds)
Step 4 – Add the figure from step 3 to the lower side of the sidereal time from table of ascendants. So you will get the longitude of the ascendant.
Step 5 – As the table of Ascendants gives the Nirayana longitudes of ascendant, we have to apply ayanamsa correction to get the correct longitudes for ascendants. So refer Page no. 6 of ‘Table of Ascendants’ and apply the correction for the corresponding year. Also note down the prefix (+) or (-) appropriately.The resulting figure will the longitude of the ascendant.
Let us take one example to illustrate the steps above.
We will find out the ascendant for the given time at September 24 2014 at 8:45 AM Bangalore
First we will find out the Local Mean Time
Step 1 – Longitude of standard meridian of India – 82°30’E
Step 2 – Longitude of place of birth for Bangalore – 77°36’E
Step 3 – Difference of two longitudes – 82°30’ – 77°36’ = 4°54’
Step 4 – Multiply by 4 – = (4*4) : (54*4)
. = 16 : 216
. = 16+3 : 36 (216-180=36)
. = 19min 36sec
Step 5 – Since longitude of Bangalore is towards east to S.M. prefix ‘-’ = -19min 36sec
Step 6 – Apply LMT correction = 8 hr 45 min – 19 min 36 sec
. = 8hrs : 25min : 24sec
The LMT correction is readily available in the book ‘Table of Ascendants’ from page No. 100 for different cities.
Let us find out the Sidereal Time for given moment
Step 1 – Sidereal time at 12h for 24 Sept
from Page No. 2 of ‘Table of ascendants. 12h : 10m : 32s
2 – Correction for 2014 (table II on page 3 and 4) (+) 1m : 34s
3 – Correction for bangalore (table III on page 5 &
100 to 107, For non-Indian cities refer page 109 to 111) (+) 0m : 2s
Step 4 – Sidereal time on 24-04-2014 12h : 11m : 68s
Therefore 12h : 12m : 08s (A)
5 – Given birth time 8h : 45m : 00s
LMT Correction (from Page No. 100) for Bangalore 19m : 36s
LMT of the birth 8h : 25m : 24s
6 – Time Interval (TI): Since it is AM birth,subtract LMT
. from 12h Noon 12h : 00m : 00s
. (-) 8h : 25m : 24s
. 3h : 34m : 36s
7 – Correction to increase TI from IV (page 5)
. for 3 hrs (+) 0m : 30s
. for 34m : 36s (+) 0m : 06s
. 3h : 34m : 72s
. Therefore 3h : 35m : 12s (B)
8 – Since AM Birth (A)-(B) 12h : 12m : 08s
(If it is PM Birth add (A) and (B) (-) 3h : 35m : 12s
Sidereal Time of Birth 8h : 36m : 56s
Calculate Longitude of the Ascendant
Step 1 – For Bangalore Latitude is 12°58’N from Page No. 20
. For 8h : 40m 6s : 15° : 58’
. 8h : 36m 6s : 15° : 01’
For variation of 4 min (+) 57’
2 – Subtract sidereal time from nearest 8h:36m 8h : 36m : 56s
. 8h : 36m : 00s
If it is more than 1 minutes convert it into seconds 56s
3 – Multiply the figures from step 1 and 2
i.e. (57*56)/240 = 13.3
4 – Therefore 6s : 15° : 01’
. (+) 13’
. 6s : 15° : 14’
5 – Ayanamsa correction: refer Page no. 6 of
‘Table of Ascendants’ for 2014 (-) 1° : 04’
. 6s : 14° : 10’
6s will be Libra (It starts from Aries as ‘0’, 1 for Taurus etc)
So the ascendant will be in Libra and longitude will be 14° 10’