# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Longitude, zone time, and local mean time
From: Bruce Cutting
Date: 2018 Oct 29, 14:02 -0600

```Easiest way to work with LMT is to realize that you need to convert
between ARC_SECONDS to SECONDS OF TIME

1)Derive the conversion by dividing ARC_SECONDS in 360 DEGREES by number
of seconds in 24 HOURS - the time for earth to turn 360 degrees. Each
second of arc = 360[degrees]*60[Min/Deg]*60[Sec/Min] / (24[hr/day])*(60
[Min/Hr])*(60[Sec/Min]).  Works out to 360/86400 which computes to
==> 15[Arc_Sec/Sec_Time] <==  Call it  AC/Sec.

2) Now compute the number of arc seconds between ZONE CENTER and YOUR
POSITION ==> Delta_AC <== (the number of seconds of LO between YOUR
POSITION and ZONE CENTER)

3) Now compute TIME DIFFERENCE ==> Delta_AC/(AC/Sec) <== Giving Seconds of
time between your position and the Zone center.

4) Recognize that this is Positive if you are West of Zone center
(occurrence will be Later than at Zone center) and Negative if you are EST
OF ZONE CENTER.

Hope this helps.

On Mon, October 29, 2018 13:15, Steve E. Bryant wrote:
>

>
> “Question dealing with longitude, zone time, and local mean time”
> I encountered the following question while going over an old quiz.
> “You are at Lo 156˚36.8’E.  If the ZT is 2345, what is LMT?
> The answer I got is 00hours 11minutes 27seconds into the next day.
> While I believe I am on a correct path in solving this question, I am not
> comfortable with my ability to explain it.  Please comment. seb, okc
>
> [plain text auto-generated]
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> -2018-g43203

```
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