(meteorobs) OT- Map question.

[David Entwistle]

In message <000b01c96abb$fe3cb5f0$27d3d74c at NAMELESSONE>, stange 
<stange34 at sbcglobal.net> writes
>I have a 1965 raised relief map of California I use to estimate fireball
>explosion positions. It is a Nystrom "Lambert Conformal Conic Projection" 1:
>1,000,000.
>
>My question is how close are the Longitude lines in (alignment) to TRUE
>NORTH ?
>
>Latitude or elevation is not an issue. Thank you.
>
>(I have had varying answers from Nystrom, who suggested aligning the map(?)
>with a compass, then rotate the map CCW 16 degrees ). There are no magnetic
>declination reference marks on this map. Just latitude and longitude.
>
>Larry
>YCSentinel
>


Hi Larry,

I think there may be some confusion here. To quote from the UK's 
Ordnance Survey web site... True North: the direction of a meridian of 
longitude which converges on the North Pole.

<http://www.ordnancesurvey.co.uk/oswebsite/aboutus/reports/misc/north.htm
l>

So, lines of longitude are aligned exactly to true north.

Maybe you are thinking of magnetic north and magnetic deviation, which 
does vary from place to place and from time to time?

See also

<http://www.ordnancesurvey.co.uk/oswebsite/gps/information/coordinatesyst
emsinfo/guidecontents/index.html>

-- 
David Entwistle