|Rectification is the process of determining someone's birth time from events in the person's life. The astrologer attempts to figure out what time the person must have been born in order for the events to have occurred when they did. If your birth time is taken from a birth certificate or birth record, then it is not necessary to rectify the birth time, although some astrlogers do like to rectify even recorded birth times because the person recording the birth time may not have been careful in noting the exact time of birth. Rectification can be used both in cases when the birth time is completely unknown and when it approximately known.
Kepler has this capability of assisting you in rectifying a chart. To rectify the chart, you enter major events in the person's life and the predictive methods on the right. Shown on the right are the screens for selecting the forecast methods desired and for adding events.
Important dates such as marriage, birth of children, accidents, relocating, etc. only are used to rectify the chart. As you can see on the screens shown on the right, you can check various predictive methods, such as transit-to-natal, Day-for-a-Year progressed-to-natal, Day-for-a-Year progressed-to-progressed, etc. Different astrologers prefer different methods.Kepler produces a total score for how well the dates could have been predicted based on the birth time. Then you can adjust the birth time and produce a new set of scores. You can also change the astrological weighting for each transiting or progressed aspect if you have your own theories about what astrological factors are likely to result in particular kinds of events.