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I'm using bird banding (ringing for Europeans) records to study the relationship between sunrise azimuth and migration heading. I have the banding (ringing) locations for several thousand birds from Europe and North America for a period of 1935 - 1990. My initial analyses show that there's a relationship between sunrise azimuth, sun altitude at noon and the direction the birds migrate in the fall.

The relationship varies with date, so my initial plan to use the US Naval Observatory's calculator ( http://aa.usno.navy.mil/data/docs/AltAz.php ) is becoming far too time-consuming. I've looked at the packages maptools and moonsun in R, but haven't been able to figure out how to run their respective commands with matrices, rather than for single dates and locations.

In addition, I don't need the time of the sunrise, just the azimuth. The values don't have to be accurate to more than a degree either. If anyone has any suggestions, i'd love to hear from you.

Hannele
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user1944480
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  • Maybe look here: http://stackoverflow.com/questions/257717/position-of-the-sun-given-time-of-day-and-lat-long – Mark Miller Jan 03 '13 at 03:35
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    And here: http://stackoverflow.com/questions/8708048/position-of-the-sun-given-time-of-day-latitude-and-longitude – Mark Miller Jan 03 '13 at 03:40
  • The question is not clear. which commands did you try to use in the vectorize version? Maybe by giving some code you get more help. – agstudy Jan 03 '13 at 08:10
  • Yes, if you post the code for a single date and location, the rest will be a simple `apply(matrix,1,function)` – nograpes Jan 03 '13 at 10:57
  • with maptools try crepuscule(mat, dates, etc) it's already vectorized – mdsumner Jan 03 '13 at 13:06

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