Notes: All timings are represented in 24-hour notation in local time of Cambridge, United States with DST adjustment (if applicable).
Hours which are past midnight are suffixed with next day date. In Panchang day starts and ends with sunrise.
Navami Homa is very significant ritual during Navratri and Durga Puja. Navami Homa is also known as Chandi Homa, Chandi Homam or Navami Hawan. People perform Navami Homa to please Goddess Durga and seek Her blessing for the good health and the victory over all sort of obstacles in life.
Navami Homa during Navratri and Durga Puja is done during day time as it is believed that Homa done during night is not fruitful. Hence Navami Homa is done during day time while Navami Tithi is prevailing. Homa during Durga Puja is suggested after Navami Puja.
Most people perform Navami Homa while chanting 700 verses from Durga Saptashati and Aahuti (आहुति) is done on each of the verse. Hence one needs at least 2 to 3 hours to perform ritualistically minimum Homam during Navami. In some years Navami Tithi gets over pretty soon after sunrise and one doesn't get enough time to perform Navami Puja and Homa.
If Navami Tithi gets over pretty soon after sunrise then it starts before Sayanakal on previous day and a good portion of Navami Tithi prevails on Ashtami Tithi. If it happens then Navami Homa can be done on the previous day and it is suggested in religious texts. The Homa on Ashtami Tithi could be started any time while Ashtami Tithi is prevailing and should be finished when Navami Tithi starts prevailing but before sunset. In other words Homa should be continued while Tithi crosses over Ashtami to Navami.
Drik Panchang lists the appropriate timings to perform Navami Homa during Durga Puja. If Navami prevails for more than 3 Muhurat on previous day before sunset then we list Homa timings on Ashtami Tithi as well as on Navami Tithi.