The D60 chart, and why your birth time decides whether it means anything

The shashtiamsha, usually written D60, is a chart derived from your birth chart by cutting each of the twelve signs into sixty equal parts of half a degree each. It is the finest division in ordinary traditional use, and Parashara gives it unusual weight when judging how strong a planet really is.

It is also the chart most easily destroyed by a wrong birth time, and for most people the birth time is not accurate enough for it to mean anything at all. Both of those statements are true together, and a page that gives you the first without the second is not being straight with you.

How the D60 is built

A sign is thirty degrees wide. Divide it by sixty and each part is half a degree, which is thirty minutes of arc. Take any planet's position in your birth chart, work out which of those sixty parts it fell in, and that tells you the sign it occupies in the D60.

The source for the method is the Brihat Parashara Hora Shastra, which lists the sixty divisions by name and gives each a character. Some of those names are benign, such as Amrita and Poornachandra. Some are distinctly not, such as Ghora, Kaala and Mrityu. Parashara treats the placement in this division as one of the heavier factors when weighing a planet up, which is why the chart is taken seriously despite its fragility.

That is the whole mechanism. There is nothing hidden in it and nothing that requires an initiation to understand.

The birth time problem, in numbers

This is the part that decides whether your D60 is worth reading.

The ascendant moves through roughly one degree every four minutes. A D60 division is half a degree wide. So the ascendant changes its D60 sign about every two minutes. A birth time that is wrong by ten minutes gives you a completely different D60 ascendant, and a birth time that is wrong by half an hour gives you a chart with no relationship to your own.

The Moon is the fastest of the planets and covers about half a degree an hour, so the Moon's D60 changes roughly once an hour. Even that is finer than most recorded birth times.

Now consider where birth times actually come from in India. A hospital record, if you are fortunate. More often a family memory, rounded to the nearest quarter hour or the nearest hour, sometimes recalled decades later, sometimes taken from a clock nobody had checked. A time given as "about half past six in the morning" is a range, not a number, and a range of fifteen minutes covers seven or eight different D60 ascendants.

So when an astrologer reads a detailed D60 from a time your mother remembered, the reading is not wrong because the technique is wrong. It is wrong because the input was never precise enough for the technique.

What rectification can and cannot do

Rectification is the practice of narrowing a birth time by working backwards from events whose dates are known: a marriage, a move, a bereavement, an illness, a job that started on a particular day. If the events are numerous and properly dated, the time can often be tightened usefully.

Two honest limits. First, it is a craft rather than a calculation, and two competent astrologers working from the same life can arrive at times a few minutes apart. Second, a time rectified to within five minutes is good work, and five minutes is still two or three D60 divisions of the ascendant. That is enough to trust the birth chart and the main divisions. It is not enough to build an argument on the D60 ascendant alone.

I will do a rectification where a person has a real list of dated events. I will not pretend the result is exact to the minute.

How I actually use it

In order, and the order matters.

The birth chart first. Sign, house, ownership, aspect. This carries most of the weight and it is robust to a few minutes of error in almost every respect except the ascendant degree.

The main divisions next, as a check on strength and on specific subjects, such as the ninth division for marriage, which is discussed in the piece on exalted Saturn.

The D60 last, and only as confirmation. If the birth chart and the divisions already point the same way and the D60 agrees, that is worth noting. If the D60 disagrees with everything else, I assume the birth time is off before I assume the chart is telling me something profound.

What I will not do is lead with it. A reading that opens with your D60 and works outward has put its weakest evidence first.

The past life question

The tradition does speak about this division in terms of accumulated karma, of what a person is held to arrive carrying. That is genuinely what the texts say, and I am not going to pretend otherwise to sound modern.

What I will not do is tell you who you were, what you did, or what you are paying for. Nobody can check such a claim, which is exactly why it gets made, and half a degree of arc from a birth time somebody rounded to the nearest quarter hour is not a foundation for it. If a reading of your past lives is what you are being sold, ask how precise your birth time is first, and watch what happens to the answer.

If you want your chart read carefully, with the strong evidence weighted first and the limits stated, that is what a reading is meant to be.

Three questions people ask

Is the D60 more accurate than the birth chart?

No. It is finer, which is a different thing. Finer means it resolves smaller detail and also that it degrades faster when the input is imprecise. The birth chart remains the primary document and everything else is read against it.

My birth time is only known to the hour. Should I bother with a D60?

Not as evidence. With an hour of uncertainty the ascendant covers roughly fifteen degrees, which is thirty different D60 divisions, and even the Moon has moved through one. You can still get a good reading from the birth chart. You cannot get a meaningful D60, and an astrologer who gives you a detailed one anyway is filling in.

Why do two astrologers give me different D60 charts from the same birth details?

Usually one of three reasons. They are using different rounding or a different birth time. They are using different software with a different setting for the ayanamsha, the offset between the fixed and moving zodiacs, and at half a degree per division even a small difference in that offset moves planets between divisions. Or they are using different rules for constructing the division itself, which do vary between schools. At this level of fineness those small differences matter, which is another reason to treat the chart as a check rather than as proof.