Time Corrections Calculated from a Reference Point
The method of calculating Location Time (or City Time) as well as
calculating LMT or any local time to the reference location by which the
birth was timed:
1. Time meridians are designated for every 15 degrees of longitude,
which equates to one hour of time. There are 24 one-hour meridians around
the earth:
24 x 15 = 360 degrees of longitude, or 24 hours of time
15 degrees of longitude equals 1 hour of time
1 degree of longitude equals 4 minutes of time
1 minute of longitude equals 4 seconds of time
Greenwich
+ | -
West | East
If birth is West of Greenwich, add | If birth is East of Greenwich, subtract
the correction to find what time it is | the correction to find what time it is
at Greenwich (GMT) | at Greenwich (GMT)
Example: Person born at 9:00 a.m. in California at PST meridian
(8 hr. west) = +8 hrs:
9:00 a.m. plus 8 hrs = 17:00 GMT.
Example: Person born at 9:00 a.m. in Europe at MET (or CET)
meridian (1 hr east) = -1 hr:
9:00 a.m. minus 1 hr = 8:00 GMT.
2. When the birth is recorded on LMT (local mean time), the correction
of longitude to time is made in reference to the meridian location.
Location
- | +
West | East
If birth is West of the location, subtract | If birth is East of the location, add
the correction to find what time it is | the correction to find what time it is
at the location (LMT) | at the location (LMT)
Example: Person born 9:00 AM LMT, Example: Person born 9:00 AM LMT,
in San Francisco (122 W.25) in Los Angeles (118 W.15)
PST meridian is 120 W.00 PST meridian is 120 W.00
122 W.25 120 W.00
120 W.00 118 W.15
-------- --------
2 25 1 45
x4 x4 x4 x4
-------- --------
8' 100" =0" 4' 180" = 7'00"
9:00AM LMT 9:00AM LMT
-9'40" = +7'00" =
----------- -----------
8:50:20 LMT 9:07:00 LMT
(which is then 8 hrs plus to GMT) (which is then 8 hrs plus to GMT)
3. Rather than correct the LMT to the nearest meridian, the correction
may be made directly to Greenwich to find GMT.
San Francisco, CA Los Angeles, CA
122 W.25 118 W.15
x4 x4 x4 x4
-------- --------
488' 100" = 472' 60" =
489' 40" = 473' 00" =
8 hrs 9 min 40 sec plus to Greenwich = 7 hrs 53 min plus to Greenwich =
17:09:40 GMT 16:53:00 GMT
4. When a birth is recorded on a location time, such as Paris
time, Rome time, etc, the correction of the birth time is made to the
reference point of the location.
Example: Person born at 9:00 AM Paris time Example: Person born at 9:00 AM Paris time
at Marseilles, France, 5 E.24. at Ault, France, 1 E.27.
Marseilles 5 E.24 Paris 2 E.20
Paris 2 E.20 Ault 1 E.27
------ ------
3' 4" 0' 53"
x4 x4 x4 x4
------- -------
12' 16" 0' 212" = 3'32"
Marseilles if east of Paris so the correction Ault is west of Paris so the correction
is added to find the time at Paris = is subtracted to find the time at Paris =
9:00 AM Paris time 9:00 AM Paris time
+12:16 -3:32
------- -------
9:12:16 AM LMT 8:56:28 AM LMT
5. Birth recorded to a location time such as Paris time, Rome time,
etc, may be corrected directly to GMT by using the standard correction of
the reference location.
Example: Person born at 9:00 AM Paris time | Example: Person born at 9:00 AM Paris time
at Marseilles, France, 5 E.24. | at Ault, France, 1 E.27.
|
0 West Greenwich 0 East
Paris 2 E.20
x4 x4
-- --
8' 80"
= 9' 20"
Paris is 2 degrees 20 minutes east of Greenwich; multiple degrees and
minutes of longitude by four to find minutes and seconds of time. The
Paris time correction will always be minus 9'20", to Greenwich.
In both examples, the birth time of 9:00 AM Paris time may be corrected
to Greenwich by subtracting 9'20" = 8:50:40 AM GMT. In common
practice, the seconds are often rounded off to the closest minute.
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