"DaveC" wrote in message
al.net...
How does LST correlate to our terrestrial time? I'm not looking for a
definition, or an explanation that includes angles of the equinox, or
such. I
just want to know if a particular time in LST is fixed in relation to the
clock on the wall, or if it changes over the year, and how to calculate it
or
look it up.

Thanks,
You are really saying, "I don't want a definition", but "I want a
definition"...
A sidereal day, is four seconds shorter then the normal 'clock' day. So a
particular sidereal 'time' arrives four seconds earlier each day (when
compared to a normal clock).
Now the question of calculating it, depends on just how accurate you want to
go?. The simplest way (which is accurate enough for most uses), is to use a
chart, based on this 'drift' between the clocks. One is at:
http://pietro.org.tripod.com/Astro_U...ealVSCivil.htm
This is accurate enough for probably 98% of uses.
The formula to calculate the sidereal time is at:
http://www.space-plasma.qmul.ac.uk/h...rt/node10.html
and this is accurate enough for 99.9999% of applications.
Even this though, has a small amount of residual error.

Best Wishes