Hours which are past midnight are suffixed with next day date. In Panchang day starts and ends with sunrise.
All Purnima Tithis are considered auspicious among Hindus. Chaitra Purnima is the first Purnima in the year according to Hindu lunar calendar and it comes after Yugadi and Gudi Padwa.
All Purnima days have something special to celebrate for. Hanuman Jayanti falls on Chaitra Purnima day and this day is celebrated as birth anniversary of Hanuman.
People worship Lord Satyanarayana, an extremely benevolent form of Lord Vishnu, and observe Satyanarayana fasting on Purnima day.
Many communities observe one day fast on Purnima Tithi according to their Kul Parampara. Kul Paramparas are family traditions passed from generation to generation.
Chaitra Purnima should not be confused with Chitra Purnima which is fixed based on Tamil Solar calendar. Chaitra Purnima and Chitra Purnima might fall in two different months.