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Bill you wrote:
"If you are not presetting to  the the approximate
separation, getting an initial rough alignment can be  difficult.  For stars
at sea, some texts recommend inverting the sextant  and viewing the star
directly while moving the reflected horizon (much easier  to see) into
approximate position.  Then flip the sextant and go for  final alignment."

Which raises a question, why flip it for the final  alignment? Partly it's
just less awkward, but it also highlights those two  different methods of
swinging the arc.

And:
"An observation:   Frank's site rounds observation (lunar) error in 0.1'
increments.  If I  recall, Frank stated the error in longitude was simply the
observation error  times 30.  Since the errors in longitude are not multiples
of 30, I  would guess they are calculated prior to rounding the  observation
error.  In which case, if you want to be really anal, divide  the longitude
error to get the actual observation error before  rounding.  For example, one
of my observations showed -0.2' observation  error and  -5.0' longitude
error.  -5.0/30 = -1.67, better than the  -0.2 would indicate.  One -0.1
observation error showed a -4.4'  longitude error.  -4.4/30 = -0.147', so not
as good as -0.1' would  indicate."

But remember, the clearing calculation can be no more accurate  than the
altitude corrections. The refraction is no more accurate than the  nearest tenth
of a minute of arc, so that's all there is in there. Dividing the  longitude
error by 30 may "look" more accurate, but those extra digits are just  junk
data. I think I should probably drop this "cheap" longitude error  correction
completely.

And:
" I warmed up the car while doing the  observations,
then brushed the snow off and scraped the ice from the windows  before I went
out to stock up on food and beer before the temperature became  sub 0 on both
the F and C scales."

Hah. Myself, I'm hoping for a  "forty below" this winter so that I can be the
only guy in the room who knows  that it's the same temperature on both scales
.

-FER
42.0N  87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars

   

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