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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: GPS Timing
From: Steven Wepster
Date: 2002 Jul 29, 14:37 +0200
From: Steven Wepster
Date: 2002 Jul 29, 14:37 +0200
Hi Vic, While doing astron navigation, an error of one second in time will give you a longitude error of 15 seconds of arc, since the earth is spinning through 360 degrees in almost 24 hours. A good astro fix might have an error of 1 or 2 minutes of arc. I think missing one or two seconds is tolerable; remember the old books that tought you to take a shot and then count out loud while stumbling back into the cabin on your way to the precious chronometer that hasn't been checked for three weeks. But, if you practice astronav for in case GPS fails, then you better buy yourself a wrist watch. I think it's preferable to keep systems separate; if you trust on GPS for your time signal then the breakdown of GPS implies the breakdown of your astro. That's bad. Hope this helps, Steven. ----------------------------------------------------------- Steven Wepster wepster@math.uu.nl tel +31 30 253 1531 Mathematisch Instituut Universiteit Utrecht PO Box 80.010 3508 TA Utrecht The Netherlands ===========================================================