Usually avoided for new starts. Traditionally avoided for starting new ventures, travel, ceremonies and signing agreements. Routine work goes on as usual.
Rahu Kaal is about 90 minutes each day, linked to Rahu. It is one of eight equal parts of the daytime.
How it is worked out
Daylight is split into eight equal parts. Rahu Kaal is the 8th part on Ravivar, 2nd on Somvar, 7th on Mangalvar, 5th on Budhvar, 6th on Guruvar, 4th on Shukravar and 3rd on Shanivar. The parts are measured from sunrise to sunset, so the time shifts a little every day and from city to city.
What people do
Many families avoid it for beginnings such as a journey, a purchase, a ceremony or signing an agreement. Work already under way, and everyday routine, go on as usual.
Times are worked out for Chennai from its sunrise and sunset. A difference of a minute or two from a printed panchang is normal.