NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: An equal altitude puzzle
From: Peter Hakel
Date: 2013 May 18, 20:19 -0700
From: Frank Reed <FrankReed@HistoricalAtlas.com>
To: pmh099@yahoo.com
Sent: Saturday, May 18, 2013 7:45 PM
Subject: [NavList] An equal altitude puzzle
From: Peter Hakel
Date: 2013 May 18, 20:19 -0700
May 19, 2013
GMT: 02:00:00
Capella:
GHA: 187° 29.7'
Dec: N 46° 00.5'
Procyon:
GHA:151° 54.7'
Dec: N 5° 11.2'
Great circle distance:
3067.7 nm, or, 51.1283°
divided by 2:
25.5642°
which, when taken as zenith distance, is equivalent to Ho:
64.4358°
With these GP's and this Ho the two circular LOP's touch at the midpoint between the GP's.
This equal-altitude LOP is a great circle that runs through this midpoint perpendicular to the great circle connecting the two GP's.
Without running down every last decimal place, this great circle runs through:
Lat: N 26° 42.6'
Lon: W 166° 22.0'
and
Lat: N 26° 37.9'
Lon: W 166° 29.5'
i.e., about half-way between Hawaii and Midway.
Additional constraints provided by Frank would limit the possibilities to an arc on this great circle in the general vicinity of these two locations.
GMT: 02:00:00
Capella:
GHA: 187° 29.7'
Dec: N 46° 00.5'
Procyon:
GHA:151° 54.7'
Dec: N 5° 11.2'
Great circle distance:
3067.7 nm, or, 51.1283°
divided by 2:
25.5642°
which, when taken as zenith distance, is equivalent to Ho:
64.4358°
With these GP's and this Ho the two circular LOP's touch at the midpoint between the GP's.
This equal-altitude LOP is a great circle that runs through this midpoint perpendicular to the great circle connecting the two GP's.
Without running down every last decimal place, this great circle runs through:
Lat: N 26° 42.6'
Lon: W 166° 22.0'
and
Lat: N 26° 37.9'
Lon: W 166° 29.5'
i.e., about half-way between Hawaii and Midway.
Additional constraints provided by Frank would limit the possibilities to an arc on this great circle in the general vicinity of these two locations.
Peter Hakel
From: Frank Reed <FrankReed@HistoricalAtlas.com>
To: pmh099@yahoo.com
Sent: Saturday, May 18, 2013 7:45 PM
Subject: [NavList] An equal altitude puzzle
On May 19, 2013 at 02:00:00 GMT (local date May 18), I observe the altitudes of the stars Procyon and Capella. The altitudes are exactly the same, but I'm not going to tell you the actual numerical value. Where are you? There is a specific locus of points where you might be found. Note: both stars are at least 1° above the horizon, and the Sun is at least 6° below the horizon.
-FER
PS: I added degree symbols, °, to this post using 'd' in square brackets as I described in an admin post two days ago. That is, you type ° but with a lower case d, and it will be converted automatically to a degree symbol. Just a shortcut. Works when you post from the message boards and also when posting by email.
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