Companion

Sun's zenith at astronomical twilight (108).

Sun's zenith at civil twilight (96).

90 below the vertical. Used as a basis for most calculations since the location of the sun is 90 below the horizon at sunrise and sunset. **Note **: it is important to note that for sunrise and sunset the adjusted zenith is required to account for the radius of the sun and refraction. The adjusted zenith should not be used for calculations above or below 90 since they are usually calculated as an offset to 90.

constant for milliseconds in an hour (3,600,000)

constant for milliseconds in a minute (60,000)

Sun's zenith at nautical twilight (102).

A utility method that returns a date offset by the offset time passed in as a parameter. This method casts the offset as a long and calls getTimeOffset.

A utility method that returns a date offset by the offset time passed in. Please note that the level of light during twilight is not affected by elevation, so if this is being used to calculate an offset before sunrise or after sunset with the intent of getting a rough "level of light" calculation, the sunrise or sunset time passed to this method should be sea level sunrise and sunset.