The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 05-26-2007, 07:23 AM
newcrasher newcrasher is offline
Guest
 
Join Date: Nov 2000
Help me get map co-ordinates from this google map

Once again I appeal to the hive-mind if the SDMB. In this link there is a blue marker. How can I find the map co-ordinates for this location?

I will be there in a few months and I want to enter the info into a satellite tracking site to see if we can spot any while we are there.

LINK
Reply With Quote
Advertisements  
  #2  
Old 05-26-2007, 07:53 AM
Fear Itself Fear Itself is online now
Charter Member
 
Join Date: May 2000
Location: 847 mi. from Cecil
Posts: 25,751
If you have Google Earth installed, you can just click on the KML link near the upper right corner of the map. This will open GE, and create a location in the Temporary Places folder. Click on the new location ("Pavas"), and it will zoom into it. Place your cursor on the marker, and read the lat/lon from the lower left corner of the GE window (9°57'20.80" N, 84°09'06.47 W).
Reply With Quote
  #3  
Old 05-26-2007, 09:24 AM
tomndebb tomndebb is offline
Mod Rocker
Moderator
 
Join Date: Mar 1999
Location: N E Ohio
Posts: 34,571
Actually, you already have the coordinates in your link.

If you read the url, keep reading along the (very long) address until you come to the string
&t=h&om=1&ll=
The "ll" (that is two lowercase Ls) appears to indicate Latitude Longitude..
I do not know what the "&t=h&om=1" indicates, but it is sufficiently distinct in the very long url to be seen pretty easily to help find the "ll="

The pair of numbers, separated by a comma following the "ll=" are the latitude and longitude.
In this case the latitude is 9.956709 (or a hair short of 10° North), specifically 9° 57' 24.1524" N
and the longitude is -84.15206 or (about 10 minutes west of 84° West),
specifically 84° 9' 7.416" W.
Reply With Quote
  #4  
Old 05-26-2007, 09:27 AM
tomndebb tomndebb is offline
Mod Rocker
Moderator
 
Join Date: Mar 1999
Location: N E Ohio
Posts: 34,571
The discrepancies between Fear Itself's coordinates and mine (which are pretty small, to begin with), are due to minor variations in the focus of the map and the position of the mouse when selecting the map.
Reply With Quote
  #5  
Old 05-26-2007, 09:29 AM
1010011010 1010011010 is offline
Guest
 
Join Date: Jun 1999
The "Link to this page" in the upper right corner of the map contains the lat/long
http://maps.google.com/maps/ms?ie=UTF8&hl=en&msa=0&msid=109883637077191680551.000001124aae51d676486&t=h&om=1&ll=9.956709,-84.15206&spn=0.004681,0.008454&z=18

Ninja'd by tomndebb

Last edited by 1010011010; 05-26-2007 at 09:30 AM.
Reply With Quote
  #6  
Old 05-26-2007, 10:24 AM
newcrasher newcrasher is offline
Guest
 
Join Date: Nov 2000
Thanks guys. Since Fear posted, I have spent the remainder of my day on Google Earth.

Friggin' cool stuff.
Reply With Quote
  #7  
Old 05-26-2007, 12:42 PM
threemae threemae is offline
Guest
 
Join Date: Jun 1999
I want to argue that the coordinates may not be quite as accurate as you think they are. I haven't been able to figure out what map datum Google is using. IF you are trying to find a specific place on the ground, that error could be significant if you're using different datum sets. Up to a half of a mile in places, I believe. Given that you're using it to track satellites, I'm sure it's close enough.

http://en.wikipedia.org/wiki/Datum
Reply With Quote
  #8  
Old 05-26-2007, 01:09 PM
tomndebb tomndebb is offline
Mod Rocker
Moderator
 
Join Date: Mar 1999
Location: N E Ohio
Posts: 34,571
Quote:
Originally Posted by threemae
I want to argue that the coordinates may not be quite as accurate as you think they are.
There is that. Deb's navigational GPS for her car kept giving me a reading fifty to a hundred yards off (compared to Mapquest and Google Earth). Before I decided the GPS was in error, I looked up the latitude of the Greenwich Observatory (51° 28' 38"N) and then looked that up on Google Earth. According to Google Earth, the observatory is both North of its self-identified latitude and is also West of longitude 0°.

(I have no idea how accurate Deb's GPS may be, but I am not about to gauge it based on Google Earth or the other on-line mapping services.)
Reply With Quote
  #9  
Old 05-26-2007, 06:02 PM
Colophon Colophon is offline
Guest
 
Join Date: Sep 2002
Quote:
Originally Posted by tomndebb
There is that. Deb's navigational GPS for her car kept giving me a reading fifty to a hundred yards off (compared to Mapquest and Google Earth). Before I decided the GPS was in error, I looked up the latitude of the Greenwich Observatory (51° 28' 38"N) and then looked that up on Google Earth. According to Google Earth, the observatory is both North of its self-identified latitude and is also West of longitude 0°.

(I have no idea how accurate Deb's GPS may be, but I am not about to gauge it based on Google Earth or the other on-line mapping services.)
A hundred yards or so off. That's because zero longitude on the WGS84 datum used by GPS is 336ft east of the Greenwich meridian.

There's no such thing as "proper" latitude and longitude, really. Different maps in different parts of the world use different datums. You can adjust most consumer GPS units to give the correct readout to tally with your maps.
Reply With Quote
  #10  
Old 05-27-2007, 12:51 PM
threemae threemae is offline
Guest
 
Join Date: Jun 1999
Exactly. It isn't so much "error" as it is different units.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 07:21 PM.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright © 2013 Sun-Times Media, LLC.