Line of Position

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Do all observers see the sun at the same location at dawn?

Pretty nearly. It doesn't vary as much as I predicted from drawing 2 dimensional pictures of the 3 dimensional reality.

I collected these charts and tables on 11 September 2010, which is close to the fall equinox. At dawn, someone near Buffalo would see the sun at 83.1 degrees, which would generate LOP perpendicular to the sun sighting of 353-173. The sunrise azimuth at Howland would be 85.59 and 85.65 at Niku, giving a LOP of 355-175.

I don't know whether the difference is due to the earth not being a perfect sphere or solely to the difference in the latitude of the observers.

Source: www.sunearthtools.com - Sun position calculator:

Howland

Latitude 0.80108
Longitude 176.61624
Sunrise Azimuth 85.59

2010-09-11 Howland chart.png 2010-09-11 Howland table.png

Niku

Latitude 4.67792
Longitude 174.5196
Sunrise Azimuth 85.65

2010-09-11 Niku map.png 2010-09-11 Niku table.png

Near Buffalo

Latitude 42.57264
Longitude 78.82926
Sunrise Azimuth 83.1

2010-09-11 Buffalo chart.png 2010-09-11 Buffalo table.png

Gallery

Terminator.png

Summer solstice 2 overlaid.png

Winter solstice 2.png

Summer diagram.png

Winter diagram.png