Purohit · Pitru Paksha
The shraddha belongs to the day whose aparahna carries the ancestor's tithi — and aparahna is the fourth of five equal parts of daylight, measured from your own city's sunrise and sunset. That is often not the day a printed almanac shows the tithi against, and on the same date it differs from city to city.
Bharani Shraddha — the Bharani-nakshatra day of the fortnight — is named rather than folded into the Amavasya, and regional customs beyond the rules stated on the page are left to a family priest.
The tradition itself is not unanimous here: some families keep the Indian tithi for continuity with relatives at home, others follow the sky where they live. Both are defensible. The page computes for the city you give it and says so on the answer, so you can see which convention you are being shown.
Opening your Sanatani workspace