Rahu kaal today

The day, marked

What an eighth of the day actually is

Take sunrise, take sunset, and cut the interval between them into eight equal parts. One of those eight is rahu kaal, and which one depends only on the weekday — Sunday the eighth, Monday the second, Tuesday the seventh, Wednesday the fifth, Thursday the sixth, Friday the fourth, Saturday the third.

Two consequences follow, and both are worth stating because they are usually left implicit. First, an eighth is not ninety minutes: it is an eighth of your day, so it runs about 95 minutes in a Delhi June and about 80 in a Delhi December, and longer or shorter again the further from the equator you are. Second, it depends entirely on sunrise — which means an app that is two minutes out on sunrise is two minutes out on this, and on gulika, and on yamaganda, and on every choghadiya and every hora.

That is why this surface computes sunrise by scanning the Sun’s real altitude against a refracted horizon rather than reading it from a table, and why it tells you which definition of sunrise it used. The method →

Gulika, yamaganda and abhijit

Gulika kaal and yamaganda are the same construction with different tables — a different eighth for each weekday. Abhijit is the opposite kind of thing: the eighth of fifteen equal muhurtas of the day, which puts it centred on local apparent noon rather than on clock noon, and it is the one window on the page that is considered favourable. Some traditions suppress it on Wednesday; this build declares which way it went rather than silently choosing.