The times were calculated as follows:
Alos HaShachar - 72 minutes before sunrise. This is selectable to be a fixed 72 minutes or to the time corresponding to the sun being 16.1 degrees below the horizon, which corresponds to 72 minutes in Jerusalem at the equinox.
Misheyakir - 45 minutes before sunrise.
Sunrise - When the upper limb of the sun is at the horizon.
Sof Zeman K'rea Sh'ma - 1/4 into the day.
Sof Zeman T'feliah - 1/3 into the day.
Midday - 1/2 into the day.
Earliest Mincha - 6.5/12 into the day.
Plag HaMincha - 10.75/12 into the day.
Sunset - When the upper limb of the sun is at the horizon.
Tzait Hakochavim - Both a 42 minute and a 72 minute value are presented. The 72 minute value is selectable to match Alos HaShachar.

For all times that depend on a fraction of the day, those times lables "(Grah)" use a day that runs from Sunrise to Sunset. Those labled "(Mogan Avraham)" use a day that runs from "72 minutes before Sunrise" (Alos HaShachar) to "72 minutes after Sunset" (Tzait Hakochavim). If not labled a Sunrise to Sunset day is used.

If you are interested in having other computations available, please contact our webmaster with your request.

Orginally, the program requested the geographic locations for places that were not in its database from an on-line server at the University of Michigan. That server is no longer active and the local database is maintained by hand. The database is reasonably good for locations in the U.S. but is spotty outside the US. We can add foreign cities to the local database on request. Currently time zones are not in the database for individual cities, we therefore use the information from the 1997 Nautical Almanac to determine the time zone. For States with multiple time zones we will occasionaly be wrong, but can correct any city if requested by adding the correct time zone to the local database.