Good thing that the place is mentioned, which is very important.
"AHAS", or spread of Day Time, depends on Date, Time and Place of Birth or death.
Prevalence of TITHI also depends in the same manner.
1. Selection of Sraddha Tithi: the particular Tithi should be 'present' for about 90 minutes past Mid of Ahas on that place and day.
2. For Aayushya Homam : Perform on that day when Nakshatram is present for minimum 90 minutes after Sunrise time of that place and day.
Freeware DRIK PANCHANGAM can be readily accessed to assess the above.