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-JCA Oh boy Greg, this is going to take a bit of writing.  Your
methodology is very strange to me for the sunset numbers, and gives
you the wrong answers.  I will try to work my way through it and
explain my methods.

Using the handy Arc to Time converter in the NA, 145deg 22' E yields
a
time correction of 09h 41m 28s.
-----------------------
-JCA  We agree thus far.
-----------------------
Interpolating the Sunset, Civil Twilight, and Nautical Twilight times
for N 10deg and N 20deg latitude for the 3-day period including 7 May
2008 (at Greenwich):
  SS: 18:18 Z
  CT: 18:41 Z
  NT: 19:08 Z
----------------------
-JCA.  I got 1907 for NT, but I�m not going to quibble.  What is wrong
is that this is the Time in LAT which must be converted to ZT before
use.  These times are only good on the Zone reference meridians,
including Greenwich (divisible evenly by 15).
----------------------
Applying the Arc-to-Time correction to get local time:
  SS: 20:37 (Local)
  CT: 21:00 (Local)
  NT: 21:27 (Local)
----------------------
-JCA  Here is where we get really different.  The correction from LAT
to ZT should be fairly small (<1 hr) if we are keeping the correct
zone description.  Sunset should not jump 2 hours between LAT and ZT.
    There are 2 methods to do this, apply the arc to time of the whole
longitude to bring the time back to UTC and then apply the reverse
zone description to find zone time; or 2), find the difference in
Longitude (Dlo) between the DR Longitude and the reference Longitude.
The trouble with the second is that you have to apply the correction
in the correct direction which can be confusing, especially if you are
in East Longitude and are from the Western Hemisphere.  I prefer using
the whole arc to time of Longitude to get GMT (which will be used to
get the GHA Aries later).

So we apply the -9h 41m 28s to each to get the following UTC times.
We know that we are ahead of UTC in East Longitude, so we subtract
this number:
SS: 08h 36m 32s Z
CT: 08h 59m 32s Z
NT: 09h 25m 32s Z
Add 10 hours for ZD and you get the following local ZT:
SS: 18h 36m 32s L
CT: 18h 59m 32s L
NT: 19h 25m 32s L
 ------------------
And applying the ZD-10 correction to get Z time for this location:
  SS: 10:37 Z
  CT: 11:00 Z
  NT: 11:27 Z
Now we need to calculate LHA Aries for the time we're going to be
doing
the star sights. Since the time for Civil Twilight falls neatly on an
exact hour, we can just look up GHA Aries from the NA daily page (and
don't have to do the correction for minutes/seconds)
  GHA Aries: 30deg 39.6'
--------------------------
-JCA The method is sound, the math is obviously incorrect.  I too
chose 1900L (0900 UTC) as my star time, but I got a nice easy GHA of
Aries of 000deg 34.7�.
--------------------------
Using an AP of 14deg N / 145deg 20.4' E, we add GHA Aries to our
Assumed Longitude to get:
  LHA Aries: 176deg
-------------------------
-JCA  I got 146 degrees since we add 22� longitude to 34.7� GHA to get
56.7 which is close to 60, and we carry the one to 145 to equal 146.
--------------------------------
Now using Pub 249 Vol. 1 (Epoch 2005.0), for Latitude 14deg N and LHA
Aries 176deg we get this list of stars to shoot (ALL CAPS = first
magnitude stars, [x] =  stars suitable for a 3-star fix):
  Star      Hc         Zn
  ------------------------
  Dubhe     41deg 44'  354   [x]
  ARCTURUS  53deg 19'  077
  SPICA     54deg 24'  134   [x]
  ACRUX     12deg 25'  175
  Suhail    22deg 25'  210
  PROCYON   29deg 16'  268   [x]
  POLLUX    33deg 10'  295
--------------------------------------------

-JCA  I also use Pub 249 Vol 1 but Epoch 2010 (available online).
Obviously since my LHA is different from yours, there will be slightly
different results:
1)  Dubhe  40deg 10� @012 deg
2)  Arcturus 24 deg 59� @075 deg
3)  Spica 29deg 32� @112 deg
4)  Suhail 31deg 57� @ 188 deg
5)  Sirius 36deg 18� @ 237 deg
6)  Betelgeuse 33deg 39� @ 270 deg
7)  Capella 26deg 11� @ 315 deg
------------------------
There's also a correction for precession and nutation of 03' / 110deg
T
to be applied to the LOPs and/or fix.
-------------------------
-JCA.  This is correct, but not necessary for precalculation as we
only need an approximate Hs and Zn to find the body.  Also, I was
taught to only apply this correction in off-epoch years to the actual
fix instead of the LOP�s (unless there is just one LOP of course).
The point of pre-calculating stars at sea is so that you can go out
and just point the sextant in the correct Azimuth, then the star just
pops into view.  A tiny adjustment on the micrometer drum and you take
your sight.  I can shoot a round of stars in under 10 minutes, and am
just usually waiting for the dimmer ones to appear.  For this round, I
shot 5 bodies in just over 7 minutes.
JCA

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