# NavList:

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

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Re: Sundog
From: Greg Rudzinski
Date: 2013 Feb 16, 04:26 -0800

The sundog was given at 5 degrees elevation. Sundogs form horizontally to the Sun which means the Sun azimuth for 5 degrees altitude is used to then add 22 degrees. Using the amplitude will give you an azimuth for zero altitude and thus a slight error.

Greg Rudzinski

Because this is sunset, we can use an amplitude of the sun calculation, as if we were calibrating our compass.

Known on this day is the declination = S14 deg 3.7 minutes
Latitude =N41

Amplitude = A
A= arcsin(sin(dec)/cos(lat))
A= arcsin(sin(-14.061666)/cos(41))
A= arcsin(-.3219332015)
A= -18.7798 degrees

Azimuth Z is the complement of Amplitude A so
Z =90-A
Z = 108.7798 Degrees

Sun setting at 360 - Z
Sun setting at 251.2202 degrees

The problem statement is that "you are facing the sun dog", but not the sun. The sun dog must be north of the sun, since we are facing generally west and the sun dog is to the right of the setting sun.

A sun dog forms at 22 degrees to the side of the sun. Therefore, we are facing (251.2202 + 22) degrees
= 273.2202 degrees

I am prepared to be completely corrected!

Regards

On Feb 11, 2013 2:48 PM, "Frank Reed" <FrankReed---com> wrote:
There was a very bright sundog yesterday at sunset here. Photo linked.

Here's a little navigation puzzle: you're walking in a hilly area near sunset on February 10 in latitude 41 N. You see a sundog about 5 degrees high directly ahead of you but you can't see the Sun (behind a hill to your left). In what direction are you walking?

-FER

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