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Rectification of a Birthchart

Rectification of a BirthchartOne of the most frustrating things in astrology and in erecting a birthchart is not knowing the time of birth. Rectification can help with ascertaining this although the various methods can give differing answers. Rectification can also be a useful tool in adjusting a known birth time as in many cases the actual birth time recorded has been rounded up. Even an apparently accurate recorded time may be incorrect due to the midwife's watch not being right.

It is usual in the case of unknown birth times to erect a chart placing the sun on the ascendant, i.e. a dawn chart. Otherwise, the chart can be set for midday therefore being right in the middle allowing twelve hours either side. For some astrological things this is not acceptable and some way of discovering as near accurate a birth time as possible is required.

Knowing a correct birth time is vital when using Progressions. Even a small discrepancy of a few minutes can throw the Ascendant out by a degree and therefore throw timing of progressions out by a year or more. Likewise when using Astrocartography an incorrect time can throw the angle and planetary lines way out. Most frustrating of all in not knowing a birth time is that often the sign of the Moon will not be known, or if the Moon did not change signs on that day, the degree and any aspects to it cannot be certain. Also, as the calculation of the Arabic Parts relies mostly on the sign and degree of the Ascendant, these cannot be of use either.

In any method of rectification, some sort of starting point is needed to see if the rest of the chart will work. As the Ascendant sets the rest of the chart, it is therefore a very important point. The ascendant acting like a gateway to the rest of the chart, it is therefore desirable to do all that can be done to try to establish where it should be.


The easiest method of rectification is by transits. First and foremost, the data of events in a person's life should be analyzed. Life's major events are usually shown by transits to the Ascendant or Midheaven, natal planets, and the relevant houses. At least ten such events will allow the rectification process to be more definable with regards to most likely timing. Exact dates and times are the best to use due to the accuracy of planetary positions. Just knowing a year is not of much use.

Accidents, traumatic incidents, major illnesses and the like are the best kind to use, as they are peculiar to that person rather than general to a large number. Marriage, divorce, childbirth, death of a parent or other close relative, change of employment, promotion or any other major change in circumstances affecting the native should be included. These types of things are most often shown by a major transit over the ascendant and/or MC axis or in aspect to it, though often will be found to have some correlation to the natal planets too. Naturally, the older the person, the more life experiences and therefore more to work with in the process of rectification. The events used should be spaced out as much as possible over the years. This becomes even more important if using Progressions or Solar Arcs for rectification purposes.

It is perfectly valid to erect charts for such events rather than just base it on the ephemeris. By erecting a chart it is much plainer to see the correlation between that chart and the birthchart. Even simpler is to construct a graph plotting the planetary positions for each event. This will enable easy identification of degrees that occur most prominently as they will peak in the graph. The object is to identify sensitive points which are likely to be representative of the angles of the true natal chart. The angles are the Ascendant/Descendant axis and the MC/IC axis, cusps of the first, seventh, tenth and fourth houses respectively except when using the Equal House System. The angles change by about one degree every four minutes and are very sensitive to major transits, as are the natal planetary positions. Therefore if by using event charts the major theme recurring is a hit to a natal planet, that is not very helpful initially. What we need to find are sensitive points unrelated to the planet's placements of the birthchart.

When it is noted that particular degrees are most prominent in event charts, and in particular qualities, i.e. cardinal, fixed or mutable signs, then the chances are that the most likely Ascendant and Midheaven have been found. At any given latitude the ascendant and degree is always relative to the degree of the Midheaven. So, by adjusting the birthchart in terms of the ascending degree and sign it will automatically adjust the sign and degree of the Midheaven. If the two most prominent degrees shown by the life's events charts are set so that one is the ascendant and the other the MC (Midheaven) and it works at that latitude, then this should show the natal positions of these angles.

Of course, it may be found that these sensitive points happen to be in the same position as a natal planet. This complicates the rectification procedure as, if the planet is conjunct or in a fourth harmonic aspect to the true natal angle it can overshadow the angle itself and obscure it from being an obvious sensitive point that we are hoping to find the ascendant/MC from. If no other sensitive points are located, then this is most likely to be the case.

Having found at least one sensitive point or specific degree of a quadruplicity, the next task is to ascertain whether this will be the ascendant or Midheaven. Two charts using both settings will highlight two more degrees of the other angle in each. If that then corresponds to another peak in the event charts placements you can be surer that this is indeed the rectified chart. If there occurs a problem with polarities affecting the ascendant, then both signs should be taken into account and the most likely used as the ascendant by following the verification considerations given below.

Having some idea of the time of birth, for example, born in the morning, afternoon or evening narrows down the possibilities of the ascending and Midheaven signs. Having no idea whatsoever of a time, it is necessary to try charts using a particular degree of each of the discovered quality or quadruplicity in the positions of both ascendant and Midheaven until, by elimination, only one chart remains. That will be the rectified chart and time.

The Planets

The main planets emphasized in event charts are the inner planets (Sun through to Mars) as these are most often on the angles or in major aspect to them at that time, even if they do not appear to make any major aspects to the natal planets. The slower moving planets show a general range of timing although the nature of them is often in evidence with an event. Usually it will be found that it is the coming together of all these factors that generate an event. The use of Jupiter onwards of the outer planets and maybe Chiron too are of most use if the exact date of an event is not known, disregarding the inner planets. If however, the exact date of an event is known, the Sun, Mercury, Venus and Mars can be used too with good effect.

The Aspects

In any event the harder aspects usually have a much more powerful impact and are more likely to produce those events best remembered. The hard aspects are formed by the use of the Qualities of signs otherwise known as the Quadruplicities. Each sign within a Quadruplicity forms a square and an opposition to the others and are therefore angular. These are the aspects of the fourth harmonic. So we use the square, the opposition and also the conjunction and we are thereby replicating the possible angles of the chart.

The Orbs

The orbs used should be relative to the speed of planets involved. Transits of the heavy, slower-moving, outer planets (Jupiter to Pluto) will have an allowance greater than that of the faster-moving inner planets (Sun through to Mars).

Verifying Considerations

When the data of events has been analysed and the most likely ascending sign found it can be verified or not by a study of its attributes. Bearing in mind that the ascendant or rising sign is the first impression others tend to have of someone, it may be possible to eliminate certain signs as being likely candidates. Physical appearance and general temperament are also considerations when establishing a likely rising sign. For example, dark intensity being immediately noticeable on first meeting a person is most likely to show a Scorpio ascendant, but can also be an indicator of Pluto being posited near the ascendant or in the first house.

The Ascendant ruler, the ruling planet of the sign of the ascendant, is a sensitive planet in the birthchart. So, note should be made if one planet more than any other features strongly in event charts by transits or progressions or in major aspect to it. Use co-rulers too in the case of signs having two, one by tradition (before the outer planets were discovered) and one modern. This could be a prime indicator of the ascending sign.

A study of genetic (family) charts may reveal predominant signs and thus show more likelihood of some signs rather than others. There is usually much correlation between charts of family members.

Similarly, the charts of non-family but significant people affecting the life of the native also show some correlation. Setting an event chart of the meeting with a person who in time became a partner for instance will be useful. So too will the birthchart of that person in further highlighting particular degrees.

These latter considerations should be used as a back-up source to the analytical data.

Always to be borne in mind when using rectification methods is the use of daylight saving times. To gain a possible correct time when a likely ascendant is found, it should be remembered that the time that will equate might be an hour or so different due to this.

Finally, the Moon is a "planet" to pay attention to because, as in horary astrology, it indicates a more precise timing as it shows what is happening as it aspects one planet then another. The Moon moves approximately 1 degree in two hours and can therefore pinpoint quite accurately the most likely birth time when all other considerations are taken into account. However, some astrologers prefer to discount the Moon altogether in rectification as it is so fast moving and therefore fleeting in its usefulness.

It may be beneficial in "seeing" how these rectification techniques pan out by playing around with a birthchart where the time is known. This tends to give more confidence in the process of rectification as well as helping to learn about it. It may also be found that the stated birth time is out by a few minutes or more and you will have rectified a birthchart!