Karva Chauth is a one-day festival celebrated by Hindu women four days after purnima (a full moon) in the month of Kartika. Dates differ according to the Gregorian calendar which is tabular and not based according to constellations. Karva Chauth, like many Hindu festivals, is based on the lunisolar calendar which accounts for all astronomical positions, especially positions of the moon which is used as a marker to calculate important dates.