(meteorobs) OT- Map question.

[stange]

Thanks Folks, Everything is fine.

The original difficulty was hanging the wall map on a west facing wall with 
true north a verticle direction over the marked Yuba City. I thought I could 
use the Longitudal lines because it is a conic projection map, but decided 
to check by asking around.

I cannot use magnetic readings at all. Taking the map outdoors and 
subtracting magnetic North would not do much for me because it would require 
marking an original map which would still be useless when it is hung on a 
wall. The object was to get the map aligned VERTICALLY to True North without 
regard to the frame, and where the Yuba City symbol and another Sentinel 
station location is used with my digital level & protractor to establish 
close points of meteor fallout.triangulation based on the photographs from 
two Sentinel stations. I fully understand it is a rough triangulation, but 
the fun was noting the kind of terrain features that would be encountered on 
a ground search and marking the website copy of this map with those 
estimated locations. The colorfull information & raised reliefs of 
mountains, valleys, and other such map detail make it quite picturesque.

Anyway, I need only to tilt the wall map a few degrees CCW to align the 
Longitudal lines verticle and it places the map in a position to use the 
digital measuring stuff.

Apparently my original question was widely misunderstood. Maybe because of 
how I phrased the question? However the effort to help is DEEPLY APPRECIATED 
and a credit to this very intellectual forum!

BTW- Nystrom said I should rotate the this big map ON THE WALL 16 degrees 
CCW.....

Larry
YCS


----- Original Message ----- 
From: "Chris Peterson" <clp at alumni.caltech.edu>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2009/01/01 11:27
Subject: Re: (meteorobs) OT- Map question.


> Hi Larry-
>
> Your questions have been answered elsewhere, so let me add something on a
> little different note. I don't know with what accuracy you are able to
> measure positions from your camera. Certainly, determining the position of 
> a
> fireball explosion or a meteor in an individual frame to better than a
> degree is not difficult. Plotting that on a paper map, however, is 
> difficult
> and likely to produce a significant error for a typical event 100 miles
> away. Even a conformal projection is unlikely to help all that much, since 
> a
> conformal map is only exact for a specific latitude.
>
> If your interest is to provide enough accuracy to aid in meteorite 
> hunting,
> I'd suggest abandoning the paper map completely. Computer based map 
> programs
> will allow you to accurately draw a line on a specific bearing, and will 
> do
> so correctly, without regard to projection. I mostly use Garmin MapSource,
> which is a very inexpensive program.
>
> Chris
>
> *****************************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
>
> ----- Original Message ----- 
> From: "stange" <stange34 at sbcglobal.net>
> To: <meteorobs at meteorobs.org>
> Sent: Tuesday, December 30, 2008 1:19 PM
> Subject: (meteorobs) OT- Map question.
>
>
>>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
>
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