NavList:

Er, but there are times when the clouds part long enough to give a couple of shots of "some star", no matter how carefully one pre-computes altitudes and azimuths.  Maybe the LOP crossing angle reeks and it's all less than satisfactory but if it's that or sticking with an old and questionable DR EP, I'll take the sights and be glad of them.  Even if I do view them with some caution. 

Rick Emerson

"I'd like to live in Theory.  Everything works there."  - -  Anonymous

Greg R. wrote:

--- bruce hamilton <bruce.hamilton@shaw.ca> wrote:

  

Last night, I could get a reading from a single star through a
single whole in the clouds.  My star identification skills are
still poor, and those circumstances were beyond me. Is there a
quick and dirty way to take that single observation and find what
star I was looking at using the observation, an Almanac a watch and
calculator?
    

Not to criticize your technique here (and if it works for what you want
to do, there's certainly nothing wrong with that...), but you're almost
going about it "backwards".

Usually you'll pre-compute elevations and azimuths of stars *before*
doing the sights, and then point the sextant accordingly (it's usually
pretty obvious what star you're looking for, just look for the
brightest object in the sextant's field of view... ;-)).

Vol. 1 of Pub. 249 works really good for this - they've already done
the hard work for you, all you need is LHA Aries for the time of the
sights. From that it gives you a group of seven stars pre-selected for
your shooting pleasure - even has the 3 that give the best "cut" for a
fix marked with diamonds, and 1st magnitude stars are listed in ALL
CAPS.

--
GregR


--- bruce hamilton <bruce.hamilton@shaw.ca> wrote:

  

I just received an A-10 that I got for cheap on E-bay. Well, most of
one
as is is missing the averaging mechanism, but as I plan to use it
with
my feet firmly planted on the ground, I don't need that bit. I also
managed to coax a bubble out of it too.  I must say that it is the
best
thing for us urban dwellers with no horizon handy. I might get a
calibrated A-12 next as I love the concept. Put the body in the
center
of the bubble and I have a reading. Very nice! I am a bubble sextant
fan
now.

I have one question for someone who has used one (A-10) before. What
is
the use of the frosted glass that swings over the top of the bubble
column? Mine has some faint lines on it, but it seems to me that if
the
body is in the bubble, no other reference is needed.  As well, it
seems
to me if I peek to the left of the view, I could see a natural
horizon,
if I had one. Is this possible or a pipe dream?

Another question. Last night, I could get a reading from a single
star
through a single whole in the clouds.  My star identification skills
are
still poor, and those circumstances were beyond me. Is there a quick
and
dirty way to take that single observation and find what star I was
looking at using the observation, an Almanac a watch and calculator?
I
think I found the star in the site plan section of Celest Nav on my
palm
pilot, but I would like to be able to do it without.

Thank You

Bruce Hamilton
Vancouver, BC



    

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