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Since at least a few brave souls have faced my challenge, I will give
not only my calculations, but
also the GPS fix at 1800L (away from transit) and 1900 (at transit).

My shooting method is rather simple and very similar for both of these
observations.  As you can
see, I can shoot one shot every 30 seconds or so of the same body.
The process is very quick
when the body is at a known azimuth and altitude.  Between each shot I
offset my micrometer
drum about 10' of arc and then, standing at the same place on the
bridge wing each time, quickly
aim and rock the sextant to obtain the nadir, then quickly dial in the
micrometer drum.  As soon
as I "feel" it is correct, I look down at my watch and subtract 1
second.  I then walk into the bridge
where I record the sextant reading and the time, then offset the drum
and walk back onto the bridge
wing.  The only added measure I take when shooting in heavier seas is
wait for the ship to be on an
even heel before making taking my mark.  I never lean against
anything, but use my legs as my
built in gimbal (this is the same process for Lunars as well).

The ship, with the deck of the bridge at 102' at that particular
draft, is a medium sized container
ship and height of eye on merchant bridges these days is typically
about the same for a 200 meter
long ship.  I am careful to adjust height of eye for both draft (there
is a chart posted on the bridge) as
well as my height.  The only un-accounted for variation in this is if
the ship decides to heave at that
moment, which will change things a few tenths of a minute.

My results were reduced by my celestial program SkyMate Pro, as
usual.  I chose 24 sights for my
near-transit reduction.  My "called" transit was my 18:51:19 sight,
which was pretty close since it
gave me an Zn of 180.0.  My determined Latitude was 21 deg 47.9' North
and Longitude of
130 deg 04.6' E.  The GPS fix at 1900 (the ECDIS records a position
every 3 seconds so I could
back track) was 21 deg 48.7' North and 130 deg 07.5' East.  This was a
fix error of about 2.8 nm.
To me this fringes on the unacceptable range.

For my away from Transit I used 25 sights and got a fix of 22 deg
02.8' North and 130 deg 15.1' East
The actual position at 1800 via GPS was Latitude 22 deg 01.9' North
and Longitude 130-10.7' East.
As you can see, we have a significant error in longitude here and the
fix error was 4.2 NM.  Peter's
results are better than mine, so his methodology is superior to mine
for this type of sight.

The next question is what to make of this data.  Well to me shooting
the moon as it closes on
transit isn't an efficient method of determining position.  For the
amount of work to both shoot
and reduce this sight, the accuracy just isn't there to make it worth
while.

For a multi moon sight around transit, we can see that the results are
less than stellar once
again, but certainly could be used in a pinch for ocean navigation.
Still, this sight is highly
inefficient to gain position.

As a comparison, I shot stars a half an hour later, and obtained a
1930 fix.  The error was 0.6 nm
I shot 4 stars in 4 minutes 23 seconds, with perhaps 5 minutes of data
entry and obtained a far
more accurate position in far less time.

Jeremy

PS  I would invite Antoine to do a search of the archives for my
Exercise #17 which is a single-
body fix using Venus around the time of transit.  It is a mere 17
sights over 45 minutes, so should
be easier than this example.
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