NavList:

   

Reply

"Dave Weilacher"  writes:
 > Anyone got concise definitions of various "time"s
 > and formulas for converting from/to.
 >
 > For example:
 > Zulu time
 > UCT
 > UTC

They're all the same thing - well, there are different versions of UTC
but practically speaking it's safe to assume they're the same.  "Zulu"
is courtesy of the military who assigned a letter to each time zone.
"Zulu" is the radio phonetic for the letter "Z".  UTC is derived from
the French for Universal Coordianted Time (UCT is not preferred).  GMT
(Greenwich Mean Time) is an earlier name for UTC.

 > Zone Time

The time kept within a given time zone.  For example, Eastern Standard
Time is 5 hours before UTC.  Currently the zone time here is 1855
while it's 2355 UTC.

 > Watch time

Whatever time your watch shows.  If the watch is fast or slow, it is
not the same as zone time (or UTC, if you set the watch to UTC).
Watch time is subject to all the errors inherent in any time keeping
device and these errors must be taken into account when reducing a
sight.

 > Ship's time

The same thing as watch time although it's possible the ship's clock
might keep other than zone time (e.g., UTC) to clear up problems with
changing time zones.

 > etc.

Et cetera - it's Latin and can be translated as "and others" [of the
same kind].  [g]

 > How about local apparent noon
 > Meridian passage of sun
 > ....

Quoting Bowditch, "Twelve o'clock local apparent time, or the instant
the apparent sun is over the upper branch of the local meridian.
... Sometimes called High Noon".

Apparent time, in term, is tied to the actual position and the
meridian associated with that position as opposed to zone time (where
all clocks show the same time, regardless of the longitude of the
clock).

Rick
S/V One With The Wind, Baba 35

   

Reply