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Subject: A small puzzle
From: Richard B. Emerson (navsys@XXX.XXX)
Date: Wed Sep 06 2000 - 23:57:47 EDT
While sailing back from New England, coasting down the New Jersey
coast, I did some morning sights even though I was fairly close to my
final destination. For one reason and another, I was only able to get
off shots for Jupiter, the Moon, and one star. Although the angle
between Jupiter and the Moon was only about 35 degrees, the lines were
generally usable and confirmed my position. The reductions for the
star, however, failed miserably and I have yet to figure out what went
wrong. I was pretty sure I was shooting Betelgeuse but when I reduce
the sights, the distance to the GP is something awful (about 80 miles,
to!). Now, it was early in the morning, I'd been up much of the
night and we'd been traveling fairly hard for about a week, so I was
hardly the crispest cookie in the box. [g] My first thought was that
I'd made a timing error. I've been using a stopwatch and writing down
the hack time when I start the watch. The stopwatch is a 30 minute
watch and it doesn't have a telltale for rolling over from one half
hour to the next. With all of this in mind, here's the setup:
The date is 22 Aug 2000, the AP is 39-04 N 74-40 W, the course and
speed are 224T at 5.8 kt. He is 5' and Ic is 2.0' on. The horizon
was clear and the sky was clear, too. My notes show the initial hack
time was 09:20Z (05:20EDT) (the hack changes for the last two bodies;
I waited for a lighter horizon). What follows are typed versions of
my notes; I've added the UTC times as well as watch times. Also, it's
helpful to know the bearing to Betelgeuse at the time was
approximately 110T. Finally, I chose Betelgeuse because its reddish
color makes it distinctive in the sextant's scope (4x).
Sight No. Time (WT/UTC) Hs
Betelgeuse(?)
01 08:20 09:28:20 36-23.5
02 09:34 09:29:34 36-42.0
03 10:34 09:30:34 36-52.5
NOTE!
New hack time: 09:49Z
Jupiter
04 02:04 09:51:04 63-10.0
05 03:09 09:52:09 63-18.0
06 04:04 09:53:04 63-25.5
Moon (Lower Limb)
07 05:48 09:54:48 63-53.0
08 07:05 09:56:05 63-58.0
09 07:56 09:56:56 63-59.5
Your mission, if you choose to accept it, is to figure out what went
wrong with the star sight.
Rick
S/V One With The Wind, Baba 35
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