NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Gary LaPook
Date: 2013 Mar 11, 21:20 0700
The size of the total error is inversely proportional to the square root of number of sights taken to be averaged, the more sights, the greater the accuracy. The square root of 7 is 2.6 and the square root of 13 is 3.6 so the error of the 7 shot series should be about 1.4 times larger than a 13 shot series. (3.6/2.6) If you are doing hand averaging then taking exactly 10 shots for averaging makes the averaging much easier and provides enough sights to get the error down to a usable level. From my website: "Although you can take any number of shots, it makes it a lot easier to find the average if you take exactly ten shots because it is much easier to divide the total of the readings by ten than by any other number, just by moving the decimal point. Since we don’t normally deal with sexigesimal numbers (base 60) we must use a special method to find the average of measurements taken in degrees and minutes. To find the average you add up the minutes and degrees in separate columns. Divide the sum of the degrees by the number of shots, simply moving the decimal point if you have taken ten shots. You now have degrees and decimal degrees after the decimal point. To convert the decimal degree part to minutes just remember that 0.1 degree is 6 minutes and 0.01 degree is 0.6 minutes. For example, say the total degrees of ten observations is 674 and the total of the minutes is 162. Move the decimal point of 674 total giving you 67.4. then multiply the “4" by 6 to convert to minutes making this part of the average 67̊ 24'. Next divide the sum of the minutes, again just moving the decimal point if you have taken ten shots, and this gives you 16.2' which you then add to the minutes found in the first step so the average then becomes 67̊ 24' plus 16.2' which equals 67̊ 40.2'. It takes about a minute and a half to average ten sextant shots using this method. (If you were using a calculator you would have to convert all the measurements to decimal degrees, add them up, divide by the number of shots and then convert the result back to degrees and minutes format. It is easier doing it by hand. Noonan didn’t have a calculator so he had no choice." https://sites.google.com/site/fredienoonan/otherflightnavigationinformation/recentlandfallapproach Also see: https://sites.google.com/site/fredienoonan/topics/accuracyofcelestialfixes In particular, https://b98f4441a62cb3a1assites.googlegroups.com/site/fredienoonan/resources/weems/weems314315.JPG?attachauth=ANoY7coiqSntB_DDBBgDWqh0hfuPf3V7e9YwK5R1LeHLniEGALP69mq2AFDfI4E1dXeaYFXWVodgNBpm4v7Y8etS2QmT9kTXAni0KSr0_IgMvd4wBq88uJrX8Q4wALW2050fZ4RQP2m7q5x3Sbz7OlWq5dVDleoQ6S0x3Cw_HBwY0kQefOI7i9RwZpU70zamTF6S_l5enXIFzyn9Mc7OuIjV8M6Rja7Zp4VhaWOtu9S8cwFqjRfIhsTS0SF7wsLIE_DZ5L&attredirects=0 https://b98f4441a62cb3a1assites.googlegroups.com/site/fredienoonan/resources/weems/weems316.JPG?attachauth=ANoY7coGrnlaI7NlDTsSm258zELZKft7aAeY9Z4pwlufhNtUFODqNb3jeEfACJB1BEiFizaMpSVN_k0ZV0q0V2WcTiIXB4JG4l7PXHnBOdycXfsjgCeyYkHqij6HXvWwBjIeThb9G95bHknwL2TmsZfM0Q2MkyHagXHPUdGGT2BKiFXuHXveWP5g5_M4B4Fh4IhgqNjRYfn2R5y7Gp6OYSbwza4bKUx7mbiPjVD3j1ZJIM9mIw6Tk%3D&attredirects=0 gl  On Mon, 3/11/13, Paolo Borchetta <pb@middleeastenergyconsultants.com> wrote:
