The fortnight containing the new-moon is considered auspicious by Hindus. They believe that during this period, the offerings they make, reach their late forefathers. Every month, the new-moon day is considered auspicious and poojas are made. However, no travel ought to be scheduled the first day of the new moon, as travel without moonlight in the ancient times was forbidden.
The dark fortnight of Aswayuja (September-October) is known as the Pitru Paksha (Mahalaya) or the fortnight specially sacred for offering oblations to the departed ancestors. The last day of this period, the new moon day, is considered as the most important day in the year for performing obsequies and rites. Due to the grace of the Yama, it has been ordained that offerings made during this period benefit all the departed souls, whether they are connected to you or not.