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    Re: Silicon Sea: Leg 84
    From: Dan Hogan
    Date: 2002 Oct 11, 21:27 -0700

    On 10 Oct 2002, at 22:51, Paul Hirose wrote:
    
    > > We spend 5 days at Hilo(19d 50.0'N  155d 01.0'W) then depart. We get a
    > > departure FIX at 02:27:00Hrs after sunrise on the morning of 21/07/2002.
    > >
    > > 1)  What is the Zone Time(ZT) of the departure FIX?
    >
    > I couldn't figure out the input data behind this question. A later
    > explanation, directed to someone else, cleared it up. But the scenario
    > seemed so weird, I elected to disregard the problem. If it had been me
    > taking departure, UT and position would have been recorded.
    
    Probably poor grammer on my part. You need the time of sunrise at Hilo plus
    the time enroute.
    
    > 2. Total distance from Hilo Departure Point to Hanalei Bay is 296
    > miles.
    OK
    
    > 3. At 9.3 knots, it will take 31.9 hours to cover the distance.
    OK
    
    > 4. The Sun lower limb is only 10 minutes from the zenith at the noon
    > sight. It would be difficult to secure an accurate observation, so the
    > sight should be disregarded.
    RIGHT
    >
    >
    > >     05:30:02    Moon LL
    >                                       23 20.5 Hs
    >                                        -2.5 IC
    >  108 36.9 GHA                            -2.9 D
    > -156 36.9 A lon     N21 00   A lat       65.8 R, SD, PA
    >  --------                             -------
    >  312      LHA       S24 49.5 dec      24 20.9 Ho
    >
    >   25 08.7 tab Hc    132      Z          -38.7 d
    >     -24.8 d corr
    >      -7.2 d corr
    >  --------
    >   24 36.7 Hc
    >   24 20.9 Ho
    >  --------
    >      15.8 away
    >
    >
    > >     05:34:11    Vega
    >                                       41 39.7 Hs
    >  104 05.2 GHA       N38 47.2 dec         -2.5 IC
    > -157 05.2 A lon     N21 00   A lat       -2.9 D
    >  --------                                -1.1 R
    >  307      LHA                         -------
    >                                       41 33.2 Ho
    >   41 33.5 tab Hc    N056E  Z    +5.6  d
    >       0.0 d corr
    >       4.4 d corr
    >  --------
    >   41 37.9 Hc
    >   41 33.2 Ho
    >  --------
    >       4.7 away
    >
    >
    >
    > >     05:40:00    Altair
    >                                       21 57.8 Hs
    >   87 04.6 GHA       N08 52.5 dec         -2.5 IC
    > -157 04.6 A lon     N21 00   A lat       -2.9 D
    >  --------                                -2.4 R
    >  290      LHA                         -------
    >                                       21 50.0 Ho
    >   21 28.4 tab Hc    N088E  Z    19.8  d
    >       8.8 d corr
    >       8.6 d corr
    >  --------
    >   21 45.8 Hc
    >   21 50.0 Ho
    >  --------
    >       4.2 toward
    >
    >
    > >     05:43:55    Polaris
    >                                       20 25.1 Hs
    >  347 18.8 GHA       N89 16.1 dec         -2.5 IC
    > -157 18.8 A lon     N21 00   A lat       -2.9 D
    >  --------                                -2.6 R
    >  190      LHA                         -------
    >                                       20 17.1 Ho
    >   20 00.9 tab Hc    N000E Z    59.1 d
    >      13.4 d corr
    >       2.5 d corr
    >  --------
    >   20 16.8 Hc
    >   20 17.1 Ho
    >  --------
    >        .3 toward
    >
    >
    > >     05:46:20    Regulus
    >                                       16 08.0 Hs
    >  234 16.5 GHA       N11 57.5 dec         -2.5 IC
    > -157 16.5 A lon     N21 00   A lat       -2.9 D
    >  --------                                -3.3 R
    >   77      LHA                         -------
    >                                       15 59.3 Ho
    >   15 56.0 tab Hc    N 83W  Z    19.4  d
    >       9.6 d corr
    >       9.0 d corr
    >  --------
    >   16 14.6 Hc
    >   15 59.3 Ho
    >  --------
    >      15.3 away
    >
    >
    > 5. Time to use for the fix isn't stated, so I will make it 0530Z
    > (evening of July 21 local time). My Vega LOP doesn't look too good (I
    > reversed the sign of d extracted from HO 229), but the others agree at
    > 21 00 N 157 00 W.
    OK
    
    > 6. From the fix position, Pailolo Channel entrance bears 100 true or
    > 090 by the compass. It's only 5 miles away so there's no reason to
    > attempt a highly refined answer.
    >
    > 7. We should be there in about 30 minutes.
    OK
    
    >
    > I did all plotting on a single piece of typing paper at a scale of 2
    > miles per millimeter. To do as well as I did at that scale requires a
    > lot of luck! It would have been smarter to plot the celestial LOPS on
    > a separate sheet at larger scale. In fact, plotting the whole trip at
    > such a tiny scale didn't make much sense either. I did that to fit it
    > all on one sheet. I should have just split it between two sheets. From
    > now on I'll use 1 mile per mm as my smallest scale, unless a single
    > long leg needs to be plotted.
    >
    > My "almanac" was the USNO Web site, since I don't have a current book
    > almanac. I could have simulated its hourly tabulations, but the
    > contortions would have been unnatural, so I just cheated and let the
    > UNSO crank out each body's position at the time of observation.
    Any Almanac in a storm ;^)
    
    > Sights were reduced with HO 229. Using the message to be posted to the
    > list as my sight reduction form was surprisingly inconvenient. In the
    > future I'll do it on paper.
    
    Try working up a columnar form.
    
    
    
    
    Dan Hogan WA6PBY
    C27 "Gacha"
    dhhogan1---.net
    Nav-L Page: http://www.wa6pby.com
    
    
    

       
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