# NavList:

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

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Re: Lat and Long by moon transit.
From: Peter Hakel
Date: 2011 Jan 30, 13:33 -0800

Jeremy's GPS:
Lat: N 21d 48.7'
Lon: E 130d 07.5'

Kermit's result:
Lat: 21d 47.6'
Lon: E 130d 03.2'

Hewitt's result:
Lat: N 21d 47.1'
Lon: E 130d 03.5'

Lat: N 21d 47.2'
Lon: E 130d 05.2'

The final step was the -95s DR shift from the moment of the last observation (for which I calculate the position, see attached) to UT=10:00:00.

My thanks to Jeremy, Kermit, and Hewitt!

Peter Hakel

From: Hewitt Schlereth <hhew36@gmail.com>
To: NavList@fer3.com
Sent: Sat, January 29, 2011 8:33:22 AM
Subject: [NavList] Re: Lat and Long by moon transit.

Hi Antoine -

To figure the latitude, I took Jeremy's highest Hs at 09-50-00 of  55° 27.5' and came up with  21° 45.0' N. Moving this to account for his ship's movement, gave me 21' 47.1' N at 1000.  (21° 48.7 N = GPS at 1000 GMT). So, I have him 1.6' south of the GPS. (You have him at 21° 47.6' N).

Since the altitudes were taken very close to meridian passage and were changing only a few tenths/min, I was a little dubious about how my paper-and-pencil method for longitude would turn out.

Anyway, I took the two equal altitudes - 55° 25.6' at 09-48-15 and 09-55-19 - averaged the times, and came up with an uncorrected longitude at 09-51-47 of 130° 02.1 E.  Applying the correction of .7' for ship's net motion of .4 kts directly toward the moon, gave me a longitude of 130° 01.4' E. Accounting for the ship's movement south and west between 0950 and 1000 gave a 1000 longitude of 130° 03.5' E. So, I have him 4.0' of longitude west of the GPS position of 130° 07.5' E. (You have him at 130° 03.2' E).

You and I agree to 0.5' of latitude and 0.8' of longitude.

For some reason your attachment came up scrambled on my Mac (was it doc.x?), so I don't know how this compares with others' results.

Best regards.  Hewitt

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