Use this calculator to calculate astronomic directions from Sunshots and Starshots.
- Calculation Type
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Specifies the calculation types. Select one of the following from the type list:
- Sun shot calculation: Calculates the astronomic direction from solar observations by the hour angle method and uses a multiple foresight field method.
- Star shot calculation: Calculates the astronomic direction from Polaris or star observations by the hour angle method and uses a single foresight method.
Observation Station Data
- Station Point
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Specifies the point ID for the station for which you want to calculate the direction.
- Backsight Point
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Specifies the backsight point ID for the station for which you want to calculate the direction.
- Station Latitude
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Specifies the Latitude of the station in the drawing's ambient settings format. Specify - for south.
- Station Longitude
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Specifies the Longitude of the station in the drawing's ambient settings format. Specify - for west.
- UT1 Time
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Specifies the UT1 time, which is determined by adding the correction (DUT) to the Coordinated Universal Time (UTC). UTC time is broadcast over WWV and other radio stations. You can also get DUT corrections via WWV; they are broadcast after the start of each minute.
Ephemeris Data
- GHA 00 Hours
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Specifies the Greenwich Hour Angle (GHA) at zero (0) hours for the day on which the observations were made.
- GHA 24 Hours
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Specifies the GHA at 24 hours for the day the observations were made.
- Declination 00 Hours
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Specifies the declination at zero (0) hours on the day the observations were made.
- Declination 24 Hours
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Specifies the declination at 24 hours on the day the observations were made.
- Sun Semi-diameter
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Specifies the semi-diameter of the sun.
Enter zero (0) if you are sighting either the center or both the trailing and leading edges of the sun. The left edge is always the leading edge at latitudes greater than 23.5 degrees north and greater than 23.5 degrees south. If only the left edge is being sighted (left when facing the sun), then the semi- diameter is positive; likewise, the semi-diameter is negative when only the right edge is sighted.
Observations
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Creates a new observation set.
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Deletes the selected observation set.
- Observation Sets
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Displays each observation set.
- Backsight Observation
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Specifies the backsight orientation.
- Sun Observation or Star Observation
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Specifies the sun or star observation.
- Stop Time
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Specifies the stop time for the observation.
- Observed Direction
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Calculated observed direction.
- Average Direction
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Calculated average direction.
- Mean Direction (Station To Backsight)
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Value calculated by the editor.