NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: NIST website time accuracy
From: Paul Hirose
Date: 2010 Aug 19, 11:20 -0700
From: Paul Hirose
Date: 2010 Aug 19, 11:20 -0700
Gary LaPook wrote: > I now have three clocks running on my computer, NIST ( > http://nist.time.gov/timezone.cgi?Pacific/d/-8/java# ), Navy celnav > website ( > http://www.usno.navy.mil/USNO/astronomical-applications/data-services/cel-nav-data > ) and the USNO time website that you pointed out ( > http://www.usno.navy.mil/USNO/time/display-clocks/simpletime ) I checked them against WWV on a shortwave radio. #1 was consistently a little slow, perhaps .1 second. The claimed accuracy on the Web page was 1 second or .5 second (I tested it four times). It seemed that the error would vary during the course of a single minute, but WWV was fading in and out so I couldn't be sure. At the top of each minute the error was consistent. #2 is the one I have the most experience with. Over the past couple years or so I've tested it several times against WWV and it has always been perfect as far as my ear and eye could judge. The only exception was one time when I loaded the page while a file download ran in the background, just to see if there would be an effect. The clock was off by a split second in that case. #3 was perfect. I tested it three times over the course of a few minutes. I loaded only one of these pages at a time, and kept the page displayed just long enough to catch the WWV beep at the top of the minute. --