'40' on the start of the next line then falls under the column for 'Moon Ph.%' 115, line 3 Amend pages xx-xx to pages 22-25 119 Amend Jan 17 19.0* to Jan 17 17.8* Delete Jan 31 15.6 Amend Mar 1 18.8 to Mar 1 18.5 Amend Mar 20 3.6 to Mar 20 21.5 Delete Mar 21 21.5 Add Mar 31 15.6 Amend Jun 30 16.5 to Jun 30 11.8 135 Note that the radio time signal
transmission frequency for Ottawa, Canada (CHU) changed from 7335 to 7850 kHz starting 2009 Jan 1.
We watched anxiously as the WWV radio time signal
marked 7:44 p.m.
The complex subject of celestial navigation is made simple enough for even the most non-mathematical sailor, with details on plotting position by sun, planets and stars; checking the compass by using heavenly objects; taking radio time signals
and adjusting the sextant for day-to-day corrections.
Timings good to a few hundredths of a second can be made with an ordinary camcorder by filming the event while shortwave radio time signals
play in the background.
(Radio's inventor, Guglielmo Marconi, was barely eight years old in 1882!) Today's observers will have no problems meeting these requirements, thanks to modern topo maps, GPS receivers, and shortwave radio time signals
Many observers will be aiming camcorders at their eyepieces to capture the event on videotape while radio time signals play in the background.
For decades amateurs have timed occultations by calling into a tape recorder with radio time signals playing in the background.
Anyone with a telescope can make good timings using a tape recorder or camcorder along with shortwave radio time signals
. The basic method is described on page 71 of last October's issue.