Hours which are past midnight are suffixed with next day date. In Panchang day starts and ends with sunrise.
Trayodashi Shraddha is done for those deceased family members who died on Trayodashi Tithi, including both Shukla and Krishna Paksha Trayodashi.
Trayodashi Shraddha Tithi is also suitable to perform Shraddha for dead children. This Shraddha Tithi is also known as Kakbali and Balabholani Teras in Gujarat.
Trayodashi Shraddha is also known as Teras Shraddha.
Pitru Paksha Shraddhas are Parvan Shraddhas (पार्वण श्राद्ध) and auspicious time to perform them is either Kutup Muhurat and Rohina etc. Muhurat after that till Aparahna Kala gets over. Tarpan (तर्पण) is done at the end of the Shraddha.