Rectification of a horoscope is a process, return interpretations of the look-ahead card when on known dates of the events which have already occurred in life, correction of time of the birth is made. That is, otherwise, such time of the birth in the set interval (and the interval can be from days to 10-20 minutes) steals up to make coincidence of dates of all specified already occurred events to their astrological analogs maximum.
Rectification of a horoscope is carried out as follows. The interval of uncertainty of time of the birth breaks for minutes. Then for every minute look-ahead cards for date of each provided event are under construction and the astrological probability of this event is defined. After carrying out all calculations time at which the sum of probabilities of all events is maximum gets out.
On algorithm of performance of rectification it is possible to understand that the volume of made calculations is very great. And such rectification, generally speaking, became possible only with the advent of personal computers and the programs, allowing to make all calculations. I can tell by the experience that carrying out rectification "manually", and then specifying it by means of the computer on the specified algorithm, received a razbezhka no more, than for few minutes.
In general in an astrology this procedure is considered one of the most difficult. Not all astrologers are capable to execute it rather qualitatively. However without it to speak about more or less serious individual astrological forecasts it is rather difficult.
Let’s understand why. The most mobile points in a natal chart – tops of houses (куспиды). In one minute they move approximately on one degree. At creation of look-ahead cards aspects of certain moving points to natal active points which also tops of houses, in turn, concern are anyway considered. And at uncertainty of provision of top of the house of 1 degree uncertainty of time of a predicted event can reach years and more. I think, now it is clear that if uncertainty of time of the birth makes 10 minutes (and often in maternity hospital on a label specify approximated time, time "on memory", writing down it much after the birth, and +-10 minutes are hardly essential to them), uncertainty of a forecast can be 10 years!
How in general in such cases it is possible to build any forecasts? It appears, after all it is possible, though they will give information 10 times less. The matter is that except such active points as tops of houses (which in a natal chart already 12), are used such points, as planets, the Sun and the Moon. Thus for planets, except, perhaps, Moon and Mercury, the error of time of the birth 15-20 minutes leads to a razbezhka in forecasts in some days that is not essential. The only thing that we receive instead of 22 active points only 8-10.
Still there is such astrological principle of creation of forecasts – than the active point of a natal horoscope, especially serious events in life it is more mobile generates, and on the contrary.