Next message: Frank Reed: "Re: Refraction, sunset, and HO229 beginner question"
Bill said:
> The idea struck me that at sunrise and sunset I could get a LOP without a
> sextant. One barrel of my binoculars, a heavy-duty neutral-density
filter,
> a watch, Nautical Almanac and HO229 tables would suffice.
I was struck by a possibly similar idea -- I am not sure if it's the same
idea,
because Bill's comments are mostly about use of almanac and tables, not
about
the basic principle. My idea was simply that for any observation you make
with watch and sextant where the object appears on the horizon, the same
observation could be made with watch only (or watch and binoculars). Then
you run the computations, using using zero for the sextant reading, making
all
the appropriate corrections (but using zero for the sextant index error
correction!), and you should get identical results. Possibly that's what
Bill was getting at.
Furthermore, it seems that on a moonless night you might be able to get
a LOP from the setting of a star or planet more easily using this method,
since you don't have to see the horizon, you only need to note the instant
at which the star or planet blinks out.
I wanted to test this theory on a sailing trip a couple of months ago (I
live inland, not in sight of a 'real' horizon), but weather and
circumstances
prevented it.
Regards,
Jim
