The birth horoscope and the further divisional charts are calculated on the basis of the exact birth time. You canno predict anything accurately without the divisional charts, (you need the 9th divisional chart/ Navamsha at least). So the exact time of birth is vital. There are several interpretations as to what is the exact time of birth; when the head comes out of the birth canal, or when the entire body comes out or the the first cry etc. Perhaps the true time of birth can never be determined, as it actually is the time of conception!
From the astrological point of view, ‘birth’ is when the umbilical cord is cut. This is done generally within a couple of minutes after the baby’s body is out of the mother’s body (it may be a natural birth or Caesarean birth). This is the instant when the baby becomes an individual. Now it is separate from its mother, it is now self-sustaining. Now, from this instant, its own horoscope will start operating. The baby has been born and is a separate human being when its umbilical cord is cut.
In our modern times everyone has a watch, or the hospital has a wall-clock, and the doctors/ nurses do note the birth time sincerely. If you are having a baby, you can request them to note the time when the umbilical cord is cut. Or if you are accompanying your wife in the delivery room, you can note this time accurately yourself.
Now for clients there often is a discrepancy in the birth time. There is generally an error of upto 5 mins in noting the time e.g. 12:18 may be recorded as 12:20 or 12:15. Most of the clients you get will be of this type with a few minutes off their actual birth-time. In these clients you can draw their birth chart and the D-9. The accuracy of the D-9 can be cross-checked by asking a few questions about their life events. A 5min error in birth time can be easily corrected like this. You may not be able to pin-point the exact time but the D9 generated will be good enough. In my opinion, doing the a full-fledged ‘birth-time rectification’ in such cases is not really necessary. If you can get the Navamsha chart correct you are good to go. (the other divisional charts are not necessary for the usual client questions. The birth chart and D-9/ Navamsha are enough.)
For older clients, sometimes the precise birth details are generally not available. These clients know their day of birth but not the accurate birth time. In these cases if the client is more than 48yrs old, draw the chart with the house containing the birth Moon as the first house. And read it like you would read a normal birth chart with the keywords of the houses etc. This works quite well for future predictions, and there is a valid reason for this. The planets mature at specific years of life. Rahu/ Ketu mature the last, at the age of 48yrs. After this age this birth Moon chart becomes more important than the ascendant sign birth chart.
As you know, the body is composed of five sheaths, the panch-kosh. These five sheaths are sub-divided into three types of bodies, physical body, the subtle body and the causal body. The physical body is linked to the ascendant sign/ lord. The subtle body is linked to the Moon and the causal body to the Sun. When we cross the age of maturity of all the planets ie 48yrs of age, the focus shifts to the subtle body self. The physical self has given its maximum and the environment has given its potential too. Now onwards the focus of the entire personality gradually shifts away from the material life represented by the ascendant sign and its lord. If you have crossed this age, think back on the events and experiences at the age of 46-50yrs, you will notice that gradually the charm of material achievements had subtly lessened during these years. After this age, you are more willing to be content, there is a mental stability, you are more resilient to emotional turmoil etc (unless the Moon is badly afflicted). The vagaries of the material life are less important to your sense of self-content and personal happiness. Eg a teenager gets his hand amputated in an accident, it is extremely tragic to him on all levels, physical, emotional, mental etc. And a 55yr old gets his hand amputated in an accident, it is equally tragic but he would be more able to cope with the loss on the mental/emotional levels. This is the effect of maturity of all the planets as they change perceptions.
So the point is that if you get a client older than 48yrs, and he knows his day of birth but not the exact time, use his birth Moon chart as his horoscope and predict from it. It will work.
I have seen that the easiest thing is to use Prashna kundali, rather than getting into birth time rectification. If the client has only one question uppermost in his mind, the Prashna system will give accurate answers. The time that the question is asked is used as the rising sign and the chart drawn. Reading this chart will give the answer to this single query. And often the client has one pressing query, about health, education, finances, profession, property, missing things, lost objects, medical problems, children, etc. Prashna system is quite very easy to learn. Buy the books and simply refer to the chapters. Read from the books and practice first then take on clients.
And finally the toughest, if the client wants a life reading and does not have any birth details. Now if you take this up, you have a lot of work. First to calculate his birth details, ‘birth time rectification’. Then to verify its accuracy by comparing with his life details and his physical features etc. And then predicting the future for the life-reading.
There are two ways by which you determine the precise birth details. If you are interested, look up a teacher who can teach you this, face to face.
- Palmistry – in this birth time rectification method, the vertical lines on the fingers, thumb and the base of thumb are counted and put in different mathematical formulae. This will give the year, month, fortnight, tithi (lunar phase), day, yog, karan, nakshatra etc, the time in ghati (vedic time measurements). You have to take the palm prints of the client and count the tiny lines properly on every finger, segment-wise. It is very tedious, one of my astrology teachers showed me how to do it. You can calculate the birth time upto seconds level accuracy. A competent astrologer/ palmist can do this.
- Mathematics – There are several mathematical techniques for finding the exact time of birth described by standard authors. These are pure math calculations so you need to have an aptitude for maths and a thorough knowledge of the effect planets have on the physical body structure and life events. Only an experienced astrologer will attempt this method for clients.
So in answer to your question (whoever had asked it). If your astrologer claims that he will do birth time rectification and give your exact time of birth, check if he really knows how to do it. There are these two methods for genuine birth time rectification. And if he is charging a large amount for it, it is justified as calculating it by either method takes a significant amount of time and knowledge of practical astrology.