Course / Angles, time and UT

Part I · Foundations · Page 2 of 4

Everything runs on UT

The almanac gives the Sun's position for Universal Time (UT): the time on the prime meridian at Greenwich, in London, with no daylight saving. At sea your watch keeps zone time: the world is divided into bands 15° wide, each an hour apart. Drag yourself across them.

Greenwich (London)+9+8+7+6+5+4+3+2+10−1YouN
Drag "You" east or west across the zones, and move the time.
UT (Greenwich)
03:00, Mar 20
Your longitude
W 122°30.0'
Your zone description
+8
Your zone time
19:00, Mar 19

UT = zone time + ZD. Here: 19:00 + 8 h = 03:00, and the date changes across midnight.

UT = zone time + zone description (ZD)

The ZD is a whole number of hours, + in west longitude and − in east. Off California it is +8; off Sydney, −10. Adding the ZD can cross midnight, and then the UT date changes too, so always check the date.