# NavList:

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

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Re: Time
From: Jared Sherman
Date: 2004 Nov 9, 17:16 -0500

```Doug, when you say "UTC and GMT denotes the same time zone of 0.

One can convert daylight time to GMT and vica-versa without adding the step
of getting standard time."

Are you or aren't you saying that GMT and UTC are one and the same, and that
neither one changes in any way for Savings Time? i.e. if NYC is at 15:30PM
EDT (as it was today) which was also 20:30 GMT today, we are -5 hours from
GMT today, but next June we would only be -4 hours from GMT?

That's the crux of it, I'm being told that the relation to *GMT* both does
and does not change as we get DST pulled over our eyes. I'm also being told
that the relation to GMT does NOT change, it is only UTC that changes.

----- Original Message -----
From: "Royer, Doug"
To:
Sent: Tuesday, November 09, 2004 5:00 PM
Subject: Time

11-09-04 20:42:00 UTC
is the exact same as
11-09-04 20:42:00 GMT

11-09-04 03:42:00 PM EST
is the exact same as
15:42:00  ZT

During standard time(anywhere in the world) the zone time of an area is the
time at the center of the zone.
During daylight time(anywhere in the world)the zone time of an area is
jumped to the next zone center to the EAST of the actual zone time of the
area.

ex:
120* 0' 0" W is the center longitude of zd + 8 during standard time. During
dayligt time the center of that zone is now at 105* 0' 0" W or zd + 7.
120* lon./15 = 8 hrs.
105* lon /15 = 7 hrs.

UTC and GMT denotes the same time zone of 0.

One can convert daylight time to GMT and vica-versa without adding the step
of getting standard time.Just remember the rule that the 1st Sun. of April
at 00:00:00 zt roll the clock forward 1 hour to the next zone's center
longitude and the last Sun. of Oct. at 00:00:00 zt roll the clock back 1
hour to the actual center longitude of the zone in question.
This is also important when calculating tides in areas.

```
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