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Thread: Different sunset time? What???

  1. #1
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    Different sunset time? What???

    I am going to photograph a wedding in Miami in April 2011.
    I have noticed that different websites give different sunset/sunrise times! Sometimes there is one hour (!) difference... It is a lot!

    For example if you look for the sunset time for Miami for 04/23/2011 on this website:
    http://www.timeanddate.com/worldcloc...omy.html?n=156
    or this one:
    http://www.calendar-updates.com/sun....F+Sunset+Times

    The sunset time is: 7:48pm

    On the NAVY's website: http://www.usno.navy.mil/USNO/astron...rs-one-year-us

    It is 18:48= 6:45pm!!!

    Can somebody explain this to me
    I am sure others have faced this problem as well.

  2. #2
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    Re: Different sunset time? What???

    Sounds like one is reporting daylight savings time and the other isn't.

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    Senior Member stephengilbert's Avatar
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    Re: Different sunset time? What???

    The LightTrack app on my iPad shows 7:48 P.M.

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    Sr. Administrator Jack's Avatar
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    Re: Different sunset time? What???

    From the Navy time zone page of definitions and instructions. Sounds to me like user error: http://www.usno.navy.mil/USNO/astron...rs-one-year-us ...

    >>Time Zones
    The times of the phenomena are presented in the standard time of the place requested, using the current time zone of the place. Standard time in time zones was introduced in the U.S. in 1883, but the time zone boundaries have evolved considerably since then, with places shifting from one zone to another. There is no attempt here to track such changes.

    Daylight Time
    Daylight time is not implemented in this program. When daylight time is in use, add one hour to the times listed in the table.<<
    Jack
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    Subscriber Member TRSmith's Avatar
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    Re: Different sunset time? What???

    Not to confuse the issue but aren't there 3 different sunsets? I can't remember the exact nomenclature but it's something like civil twilight, nautical twilight and astronomical twilight.

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    Sr. Administrator Jack's Avatar
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    Re: Different sunset time? What???

    Those are three different twilights . They have definitions based on how many degrees the center of the Sun is below the horizon line, and occur before Sunrise and after Sunset. If memory serves -- but don't hold me to these -- it is like 6, 12 and 18 degrees for Civil, Nautical and Astronomical. There is only one "Sunset" at any given location, and that is when the trailing edge of the Sun has dipped beneath the true Western horizon.
    Jack
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    Subscriber Member TRSmith's Avatar
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    Re: Different sunset time? What???

    Doh! Of course. Makes sense.

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