Polar Shift

How much has the Polar Shift caused by the recent 9.0 earthquake affected the
circa 2000 star charts?

Jerry

On 14 Jan 2005 19:16:39 GMT, emove (Jerry Pool) wrote:

How much has the Polar Shift caused by the recent 9.0 earthquake affected the
circa 2000 star charts?

At least a few places to the right of the least significant digit in the most
accurate catalogs. The pole position is always moving in a fairly random way,
and this tectonic event didn't have a significant effect on the orientation of
the axis.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Jerry Pool wrote:
How much has the Polar Shift caused by the recent 9.0 earthquake affected the
circa 2000 star charts?

You need to shift all of your object coordinates by one-half of a
millionth of an arcsecond.

Better update your charts ASAP!


While I marvel at the innumeracy of the press and the public during this
current game of urban myth "telephone," let me make a couple of points:

1. The shift is predicted by a numerical model developed by Richard
Gross at JPL. This is not a measurement, it's the prediction of a model.

2. Part of the reason it hasn't been measured is because the model's
predictions are too small to measure with current technology.

Example: The model predicts a speed-up in the Earth's rotation of 2.7
microseconds. The earth's rotational period can't be measured to an
accuracy any better than 20 microseconds.

http://earthquake.usgs.gov/eqinthenews/2004/usslav/neic_slav_faq.html


But, you know, just to be on the safe side, I recommend that you buy
replacements for all of your charts and charting software as soon as
possible.

Mojo
--
Morris Jones *
Monrovia, CA
http://www.whiteoaks.com
Old Town Astronomers: http://www.otastro.org

Jerry Pool wrote:
How much has the Polar Shift caused by the recent 9.0 earthquake affected the
circa 2000 star charts?

Take the data at its source, at the IERS :

http://hpiers.obspm.fr/eop-pc/produc...bined/C04.html

And you can check that nothing special happened to
the pole position on 12/26 :

http://minilien.com/?YVyrReO6D6

By the way bulletin C has just fallen :

"NO positive leap second will be introduced at the end of June 2005."

while it seemed the current value of UTC-UT1 could have justified it,

http://dulle.free.fr/alidade/leap_second.php
(in french but the plot is self explanatory)

but the trend of UT1-TAI over the last few years
might have been a good reason to delay any
positive leap second as much as possible.

-- francois meyer
http://dulle.free.fr/alidade/galerie.php?maxim=12

How much has the Polar Shift caused by the recent 9.0 earthquake affected
the
circa 2000 star charts?

At least a few places to the right of the least significant digit in the most
accurate catalogs. The pole position is always moving in a fairly random way,
and this tectonic event didn't have a significant effect on the orientation
of
the axis.

_______________________________________________ __

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


Thanks Chris

Jerry
http://hometown.aol.com/nlpjp/index.html