Lat and long help please.

[Renroc]

Can anyone tell me how to do a reciprocal bearing?? On a lat/long? I am not even sure that is what I actually mean. I have the co-ords for the cache furtherest north and west from my home and am looking to work out a cache that is the same South and East of home. Because I am E153 and the northern cache is W006 I am a little confused about crossing the 180 barrier. North is 57 and I am S28. That make a difference of 85degrees. If I go 85degrees south I end up at S113 but the E/W is confusing me. Help appreciated.

[Chwiliwr]

Can anyone tell me how to do a reciprocal bearing?? On a lat/long? I am not even sure that is what I actually mean. I have the co-ords for the cache furtherest north and west from my home and am looking to work out a cache that is the same South and East of home. Because I am E153 and the northern cache is W006 I am a little confused about crossing the 180 barrier. North is 57 and I am S28. That make a difference of 85degrees. If I go 85degrees south I end up at S113 but the E/W is confusing me. Help appreciated.

I think that you have also forgotten how many latitudes there are. Remember that the South pole is S90. I think you need to work out the great circle distance and bearing between you and N57 W6 and then calculate the reverse distance and bearing to get a point the same distance away in the opposite direction.

You need a geographical calculation website if you cannot handle the maths yourself.

[Zalgariath]

Do you mean in reference to your home as an absolute value or in reference to the accepted divisions of lat/long on Earth?

If you mean via established lat/long the furthest SE cache for every one would probably be Bi-Polar

If you mean the cache found by walking out your front door, heading SE and continuing in a straight line until you begin to get closer to home rather then further away... that's the same cache as your NW one

[Chwiliwr]

If you mean the cache found by walking out your front door, heading SE and continuing in a straight line until you begin to get closer to home rather then further away... that's the same cache as your NW one

This would only be true if the cache is directly on the opposite side of the world taking a line via the centre of the earth.

[Zalgariath]

If you mean the cache found by walking out your front door, heading SE and continuing in a straight line until you begin to get closer to home rather then further away... that's the same cache as your NW one

This would only be true if the cache is directly on the opposite side of the world taking a line via the centre of the earth.

...well give or take If the other side is in directly in Europe its easy to figure out.... if its in the middle of the ocean, slightly harders

[Renroc]

I really mean that if I drew a line from the most NW cache I have found through my home co-ords and continued along the same path SW where would I end up if I went the same distance from home as the NW cache is.

[Zalgariath]

Argh! That becomes tricky and the distances between lines of longatude change depending on the latitude! If its a short distance its not too bad but if we are talking a few thousand or even few hundred clicks it is not a straight forward calculation.

Id get a physical map, or Google Earth and draw a line on it. Calculate the distance to you most NW cache from home, then extend a line from there, through home the same distance. That should give you a rough idea of where abouts the equivalent SE cache is... if there is one

[Papa Bear_Left]

Plug in that NW point and your home coords to get the distance and bearing, then use your home coords and that distance plus the bearing with 180degrees added to it to get the SE point you're after.

http://www.movable-type.co.uk/scripts/latlong.html

[Renroc]

Plug in that NW point and your home coords to get the distance and bearing, then use your home coords and that distance plus the bearing with 180degrees added to it to get the SE point you're after.

http://www.movable-type.co.uk/scripts/latlong.html

thanks papa bear will give it a go.

[Richary]

Alternatively if you have Oziexplorer you could enter the coords for that cache NW and your home location as waypoints. That will give you a distance and bearing.

Subtract 180 from the bearing and project a waypoint from your home coords. That will give you the opposite I think you are looking for. Then do a search on the site for the nearest cache to those coords.

[Kerry]

You need to be sure exactly what you want with this one? You are talking Lat/Long and Bearing, but what type of bearing? Grid or Plane or do you actually want Azimuth? You sound like you are talking in different hemisheres? You might outline this a little further. What sort of distances are you expecting?

But with 2 points A & B in Lat/Long keep in mind the azimuth from A-B is not exactly 180 reverse B-A as grid convergence at both points will be different. A plane bearing has a reverse exactly 180 based on grid north but it's really not a lot of use over real long distances?

[Renroc]

Using Papa Bear's link I ended up with this info
Distance: 16440 km
Initial bearing: 035°10′06″
Final bearing: 159°23′02″

So now I need to go on the bearing along away from me for 16440km. I suspect I need the 035°10′06″ as the bearing from me southwest. Would this be right?

[Renroc]

You need to be sure exactly what you want with this one? You are talking Lat/Long and Bearing, but what type of bearing? Grid or Plane or do you actually want Azimuth? You sound like you are talking in different hemisheres? You might outline this a little further. What sort of distances are you expecting?

But with 2 points A & B in Lat/Long keep in mind the azimuth from A-B is not exactly 180 reverse B-A as grid convergence at both points will be different. A plane bearing has a reverse exactly 180 based on grid north but it's really not a lot of use over real long distances?

Hi Kerry,
Most of what you have mentioned above is greek to me. Yes I am talking different hemispheres and also different sides of 0 longitude.
Home is close enough to Cape Byron in Australia. The furtherest cache I have found is Kilt Rock on the Isle of Skye in Scotland.

I am beginning to think that a string line on a globe will be the easiest.

[Renroc]

01°36′48″S, 037°27′39″W Looks like the go.... Up of the north east coast of South America. BUT unless there is a submarine cache nearby there won't be an option. If I use the other bearing I end up
52°07′21″N, 056°36′20″W In Newfoundland.

[Zalgariath]

01°36′48″S, 037°27′39″W Looks like the go.... Up of the north east coast of South America. BUT unless there is a submarine cache nearby there won't be an option. If I use the other bearing I end up
52°07′21″N, 056°36′20″W In Newfoundland.

LOTS of caches in Newfie... I lived there for a while

Unfortunately pre-caching days I started when I got home from there.