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[Physltest] [Phys-L] Re: Commercial msg. Was: [Fwd: Re: [Fwd: Re: Looking for a Mars Clock?]]



Interesting to recall that John Harrison used the obscuration of a star
behind a house chimney to benchmark sidereal time.

Brian Whatcott

At 11:29 AM 1/28/2005, you wrote:
-------- Original Message --------
Subject: Re: [Fwd: Re: Looking for a Mars Clock?]
Date: Fri, 28 Jan 2005 08:00:23 -0800
From: Bryan Mumford <bryan@bmumford.com>
To: Bernard Cleyet <anngeorg@pacbell.net>
References: <41FA4D6E.50501@pacbell.net>



There is one very large problem with the Mars clock described. It won't
be accurate, because the timebase will not be accurate. The crystal will
typically have a rated accuracy of 50 ppm. An error of one second a week
is 1.65 ppm. The error of an uncalibrated clock is therefore likely to
be about 30 seconds a week. You won't notice it, of courses, if it's
your only reference for Mars time.

Mumford's clock (http://www.bmumford.com/clocks/martian) is accurate to
a second a week because the timebase is hand tuned to a precision
reference. The same thing is possible with the digital Mars clock
described if you have access to a precision frequency counter with which
to trim the timebase.




-------- Original Message --------

Subject: Re: Looking for a Mars Clock? Date: Thu, 13 Jan 2005 14:08:51
-0500 From: Edmiston, Mike <edmiston@BLUFFTON.EDU>
<mailto:edmiston@BLUFFTON.EDU> Reply-To: Forum for Physics Educators
<PHYS-L@list1.ucc.nau.edu> <mailto:PHYS-L@list1.ucc.nau.edu> To:
PHYS-L@LISTS.NAU.EDU <mailto:PHYS-L@LISTS.NAU.EDU>



By typing "Mars Clock" into Google, I came up with over 600 hits, one of
which has plans for a digital Mars Clock. Here is the URL

http://www.marsbase.net/m/mars-clock.php

It's not something anyone can do, but anyone who dabbles with digital
circuitry could do it.


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu <mailto:edmiston@bluffton.edu>



--


Bryan Mumford
http://www.bmumford.com


Brian Whatcott Altus OK Eureka!
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