# NavList:

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

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My First Lunar
From: David Pike
Date: 2014 Nov 6, 00:46 -0800

Last night I shot my first lunar and proved UTC is out by 8 minutes 49 seconds.  Do you think I ought to warn the Authorities?

It was a bit of a cheat really.  I was using newly bought Navigator 6.0.1 software, and I knew I was at 53.10N 000.32W, so I used theoretical heights for the Moon and Aldebaran for the corrections.  I also managed to do it all through my lounge window (refraction not corrected for), so I was nice and warm.  On the other hand, it was Nov 5th, Bonfire Night in the UK, and the sky was full of smoke so Aldebaran was barely visible.  Easy to identify though; it was the only star I could see.  It’s possible the far limb of the moon was the wrong one to shoot.  The moon’s almost full at the moment but not quite.

Dave

Sextant: Hughes Mate's Three Circle 1941 No: 25410

++ Lunar calculation -Aldebaran-Moon

+ inputs:

date=  5/11/2014

watch time= 21:14:54 GMT

IC= 0.0'  (index correction)

hs Aldebaran= 27°28.9'

hs Moon= 41°54.3'

ds Aldebaran-Moon= 40°36.2'    (sextant distance)

+ corrections

obj1: Aldebaran

ha = 27°28.9'

parlx= 0.0'

refr =-1.9'

(c_Aldebaran= 1.9'  refr+parlx)

hc = 27°30.8'

obj2: Moon

SD=16.2'

+ 0.2' (moon disc augmentation)

=16.4'

Lower limb for Moon

ha = 42°10.7'

parlx=43.9'

refr =-1.1'

(c_Moon=-42.9'  refr+parlx)

hc = 42°53.5'

Far limb for Moon

SD1+SD2=-16.4'

da = 40°19.8'  (apparent dist.- corr. for IC & SDs)

+refraction and parallax projection factors

A=0.5722 (Aldebaran)

B=-0.1200 (Moon)

+ results

dc = 40°26.4'  (cleared distance)

+ lunar time determination

linear interpolation 1 (1 hour interval)

NA dist @ 21:00:00   = 40°30.0'

NA dist @ 22:00:00   = 39°54.7'

Lunar Time = 21:06:05  GMT

linear interpolation 2 (5 minute interval)

NA dist @ 21:05:00   = 40°27.0'

NA dist @ 21:10:00   = 40°24.1'

Lunar Time = 21:06:05  GMT

time difference =  0:08:49    (=watch-lunar)

longitude error =  2°12.2'+

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