राहु काल
Rahu Kaal — The Daily Inauspicious Window
राहु (Rāhu, the shadow planet) + काल (kāla, "time, period") — a roughly 90-minute daily window traditionally avoided for starting anything new.
How it's calculated
Daylight (sunrise to sunset) is divided into 8 equal parts. Rahu Kaal always falls in a specific one of those 8 parts depending on the weekday, in a fixed order.
Sunday
Illustrative example: 4:30 PM – 6:00 PM
Monday
Illustrative example: 7:30 AM – 9:00 AM
Tuesday
Illustrative example: 3:00 PM – 4:30 PM
Wednesday
Illustrative example: 12:00 PM – 1:30 PM
Thursday
Illustrative example: 1:30 PM – 3:00 PM
Friday
Illustrative example: 10:30 AM – 12:00 PM
Saturday
Illustrative example: 9:00 AM – 10:30 AM
Note: the times above are illustrative only, based on a 6:00 AM–6:00 PM day. Real sunrise/sunset shift daily and by city, so the actual clock time changes — a local Panchang gives the precise window for your location and date.
Related Panchang concepts
Rahu Kaal is one of several such windows; see also Choghadiya (a fuller 8-part system) and the favourable counterpart, Abhijit Muhurta.