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Hi Jeremy, as usual great stuff. I worked your Lunar  using your
average and  graphed them. The spread was good and I noticed the line
of best fit AND sights 1,6, and 7 were parallel. I know George H is
highly critical of the "straight line" solution and rightly so but in
this and similar cases my no 6 solution and average solution yielded
GMT's of 23-16-53 and 23-16-38 a 15 sec difference and 00.8' distance
error via Bruce Stark solution. Do you graph your sights? If you do
not graph them your average may include a flyer or 2 and subsequent
erroneous results. Let me know when able and thanks much and "keep on
shootin' and reducin!"
Mike Burkes

On Oct 3, 7:42�am, Anabasis  wrote:
> � � � � The sky cleared last night (October 2, 2008) for a bit, and a �waxing
> crescent moon along with Venus appeared low in the Western sky just
> after sunset. �It wasn�t an ideal situation for a lunar, but offered a
> chance to shoot one amidst the overcast days that have plagued me for
> the past week or so. �Position is Lat 41deg 14.7�N , Long 075deg
> 53.0�W
>
> � � � � I checked the index error and found 0.9� on the arc and then
> proceeded to shoot 10 near-limb lunar distances. �Without a horizon, I
> was stuck with calculating altitudes of both Venus and the Moon.
> Temperature is 50 degrees, but pressure is unrecorded.
>
> � � � � I have recently acquired Celestaire�s new version of the 7x35 scope,
> and it was my first time to use it on my sextant. �(Thank you Ken for
> the opportunity to get one before I leave for sea next week). �The
> extra magnification certainly helped in shooting the lunars, as was
> the steady shooting platform and low altitudes of both bodies.
>
> � � � � Admittedly, this was a poor time to shoot lunars. �Both bodies were
> well below 10 degrees of altitude, and the observed lunar distances
> were just below 12 degrees, which does not usually help with accuracy,
> but I wanted to practice, so I proceeded.
>
> � � � � The observed Lunar Distances were as follows:
>
> LDs � � � � � � � � � � � � �Time (UTC)
> 11deg 56.2 � � �23h 13m 58s
> 11deg 56.8 � � �23h 14m 50s
> 11deg 56.8 � � �23h 15m 21s
> 11deg 57.1 � � �23h 15m 48s
> 11deg 57.3 � � �23h 16m 18s
> 11deg 57.1 � � �23h 16m 52s
> 11deg 57.3 � � �23h 17m 31s
> 11deg 57.6 � � �23h 18m 00s
> 11deg 57.8 � � �23h 18m 28s
> 11deg 57.8 � � �23h 19m 00s
>
> Using Frank�s calculator for the reductions, I found an average error
> of 1.11� with the outside errors being 1.3� and 0.9�. �Averaging the
> times and distances, I also got an error of 1.1�. �Since all of the
> sights seem to have a good �grouping� ie accurate, the error in
> precision is the real question. �Is it strange refraction due to low
> altitudes? �Perhaps is an error in my sextant calibration, or perhaps
> just a personal observation error. �I will have to shoot some more to
> see where the data point to.
>
> Jeremy
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