Rectification of birth time is difficult but essential part of astrology learning. In India and most part of the world it is difficult to get exact time of childbirth. So the time we get, as an astrologer, is most of the time incorrect.
There are various birth time rectification methods in Vaidic Astrology suggested by our sages. Here is a list of some popular ones -
* Parshara's method of rectification
* Varahamihira's method of rectification (Nashta Jatakam given in Brihat Jatak)
* Kalidasa method of birth time rectification
* Kerala Jyotish Rectification
* Event based rectification
* KP System method of rectification
* Nadi and Bhrigu's method of rectification
* Pre-natal Epoch
Yes, you are right, it is not a complete list of all available methods. Expert astrologers use various techniques to find correct birth time. In all these techniques, I found my own technique, which is quite reliable. First and most important, you have to determine the lagna (ascendant) rising at the birth time. For that I found the feedback method of Lal Kitab is the best method. For every planet is particular house, there are particular indications. You can find those indications (feedback questions) from Lal Kitab.
I once read a book "Grahon Dwara Lagna Evam Akriti Ki Pahchan (in Hindi)" published by "Bihari Pustak Akadami". From this book too you can get some idea of impact of various planet and rising sign on the body of the native. This book is a great asset for an astrology student. This method can also be used for finding the correct lagna.
Once you get the lagna fixed, you can use KP's ruling planets method of rectification to fix the minutes and second of birth.
I don't say that it is the best method. But I can say, atleast, that it worked very well for me.