# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: angles betwqeen lines of position
From: Gary LaPook
Date: 2012 Jul 17, 22:56 -0700
 Sorry but it is a "grevious misunderstanding my part jump out at anyone." You are confusing the change in GHA and, therefor, the change in LHA with the change in azimuth. The GHA if the sun changes at the standard rate of 15° per hour while for stars it is 15° 02.5' per hour. But the azimuth is more complicated than that since it depends not only on LHA but also on declination and latitude of assumed position. Open up HO 249 or HO 218 or HO 214 and run your finger down the azimuth columns and you will see that they don't change at a constant rate. gl--- On Tue, 7/17/12, Alan S wrote:From: Alan S Subject: [NavList] angles betwqeen lines of positionTo: NavList@fer3.comDate: Tuesday, July 17, 2012, 8:36 PMAs I understand, the sun moves around the earth at the rate of 15 degrees per hour, actually it's the earth that moves around the sun, but the rate of movement, 15 D/hr is the same. Therefore, regarding sextant shots separated by 5 hrs 26 min 17 sec, the angles between LOP's should be close to 82.5 Degrees.I shot the sun twice today, both shots from positions within a few feet of each other. First shot at 10:04:56. Second shot at 15:31:13, time between shots being 5 Hrs 26 Min 17 Sec. The difference in times should have given a spread of approximately 82.5 Degrees between LOP's.I reduced the sights and plotted them, getting a difference between KP (GPS coordinates) and calculated fix of less than 2 NM. Measuring, with a protractor, the angle between LOP's, I got 55 or 56 Degrees, instead of something closer to 82.5 Dergrees, which I think I should have gotten.Does some dumb error, or grevious misunderstanding my part jump out at anyone, or is the angle I measured about what it should be, letting the bit about 15 Degrees/hr slide? Any clarification would be appreciated, Thanks.Alan----------------------------------------------------------------NavList message boards and member settings: www.fer3.com/NavListMembers may optionally receive posts by email.To cancel email delivery, send a message to NoMail[at]fer3.com----------------------------------------------------------------
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