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Subject: Re: Silicon Sea: Leg 84
From: Dan Hogan (dhhogan1@XXX.XXX)
Date: Sat Oct 12 2002 - 00:27:13 EDT
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@XXX.XXX
Nav-L Page: http://www.wa6pby.com
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