How it works

Arithmetic for one bay.

Bay Hours computes the sun's position for a single point in the middle of Sandusky Bay, 41.48° N, 82.84° W. Nothing is looked up from anyone else and nothing is observed.

The numbers

• Sun position: the NOAA solar calculator's equations (after Jean Meeus, Astronomical Algorithms), good to about a minute for sunrise and sunset at this latitude.
• Sunrise and sunset: the moment the top of the sun meets a flat horizon, allowing 0.833° for the sun's radius and for the bending of light by the air. This is the same convention the U.S. Naval Observatory uses.
• Golden hour: the sun between 4° below and 6° above the horizon. Blue hour: between 6° and 4° below. Photographers use slightly different limits; these are common ones.
• Civil and nautical twilight: the sun 6° and 12° below the horizon.
• Moon: the phase and the share of the disc lit at midday, from the moon's and sun's positions (Meeus, Astronomical Algorithms, ch. 48). It agrees with the U.S. Naval Observatory to within a few percent; it is a guide, not a moonrise table.
• Clock: Eastern time, with daylight saving applied on the right dates, rounded to the nearest minute.

Checked against

The U.S. Naval Observatory's published times for this point on October 13, June 21 and December 21, 2026 (sunrise, sunset, solar noon and civil twilight) agree with Bay Hours to within one minute. The test suite checks this on every release.

Across the bay

The bay runs about 15 miles east to west, so a spot at the east or west end sees the sun rise or set well under a minute earlier or later than the middle. Trees, buildings and the far shore can hide the sun a few minutes before the computed sunset.

Safety

Never look straight at the sun, and never through a camera, binoculars or a telescope without a proper solar filter. Bay ice is never certain: Bay Hours says nothing about ice, water or weather. Check the National Weather Service forecast at weather.gov/cle before you go. In an emergency, call 911.

Who runs it

Bay Hours is an independent planning tool made and run by WeldonPC.com. It is not run by, or affiliated with, the City of Sandusky, Erie County, Ottawa County, any park, port, marina or business on the bay, or any government agency. “Sandusky Bay” here is only the name of the water.