Default and options
Sunrise is the default. The options panel also permits civil dawn (about 6 degrees), nautical dawn (about 12 degrees), or astronomical dawn (about 18 degrees).
Local day boundary
Dawn-to-Dawn Biblical Day in the Zadokiah Calendar
The current tool changes the displayed biblical date at the selected local dawn boundary.
Before the boundary
When local time is earlier than the calculated boundary, the tool uses the preceding civil date for its biblical calendar conversion.
Why location matters
Time zone alone is not enough for sunrise. The calculation also needs latitude and longitude. Presets supply coordinates; the displayed note names the location and exact calculated boundary.
At extreme latitudes an astronomical event may not occur on a given date. The interface reports an unavailable result rather than inventing a time.