How these dates are worked out
Each festival is tied to a tithi (lunar day) in a particular Hindu month, sometimes at a particular time of day: Diwali on the Amavasya evening, Janmashtami at midnight, Ganesh Chaturthi at midday. Makar Sankranti and Baisakhi follow the Sun instead. Every date here is calculated from the positions of the Sun and Moon and checked against published panchangs.
Dates follow the panchang for New Delhi (IST), worked out from the positions of the Sun and Moon; tithi times are shown in IST. Some regions and traditions observe a festival a day earlier or later, so check with your family priest or local temple for rituals.