Your sign, cut into three

Your date is enough. The Sun moves about a degree a day, so a birth time only matters if you were born within a day of a decan boundary.

Is this Egyptian astrology?

Yes and no, and the split is worth knowing before you read anything else about it. The decans themselves are genuinely Egyptian and genuinely old: Egyptian astronomers divided the night by the risings of thirty-six star groups, each ruling roughly ten days, and you can still see the tables painted inside coffin lids from about 2100 BCE. That is where your thirty-six comes from, and why ten degrees is the unit. What is not old is the version you will meet first if you search for Egyptian astrology: guardian deities handed out by date range, Osiris and Isis dealt like sun signs. That scheme is modern, the dates differ from one site to the next, and no ancient source assigns them. So we compute your decan, and we do not invent your guardian.

Who rules a decan

You have two rulers, not one, because two schemes exist and they disagree. Both are shown here and neither is blended into the other. The triplicity scheme walks the three signs of your decan's element in order, so the Aries decans are ruled through Aries, Leo and Sagittarius. The Chaldean scheme runs one unbroken cycle of the seven visible planets, starting at Mars in the first decan of Aries and never resetting when a sign ends. They agree sometimes and part company often. If someone tells you there is one correct ruler for your decan, they are picking a lineage without telling you they picked.

All thirty-six

Yours is in here somewhere, and so is the decan of everyone you were about to compare yourself with. Each one opens its own page.

What this calculation assumes

version

asternym-western-advanced-v1

zodiac

Tropical

decanSpan

Exactly 10°, three to a sign, thirty-six in all

decanRulers

Two schemes, both shown and never blended: the triplicity scheme walks the three signs of the element, and the Chaldean scheme runs one unbroken cycle of the seven visible planets from Aries I, never resetting at a sign boundary

decanGuardians

Not computed. The guardian-deity decans circulating online are a modern invention with no fixed date table behind them