Caching Topics A to Z # 23 WGS84/Deg Min.Dec/UTM

The Ginger Loon · Post by **The Ginger Loon** » 18 October 06 2:04 pm

Team Falling Numerals wrote:
Zytheran wrote:
Damo. wrote:
GeoScrubers wrote:And why is it that when I went to Greenwich, the GPS showed E/W 00.0000, but I was about 60m from the official meridian 
Continental drift.
Global warming
not enough pirates.

Poor Satellite Coverage

Geof · Post by **Geof** » 18 October 06 2:23 pm

Yes I use UTM & AGD66 for map related use.

So why is it that Garmin have 11 types of NAD27 and some are up to 1.5 kilometers different and Magellan have only one?

Real interesting when a magellan user quoted NAD27. Yes I did find the cache in spite of that

.

VWNuts · Post by **VWNuts** » 18 October 06 8:06 pm

I use both Degrees & UTM in my Multicache "Mountains to Mangroves" series.....just so its a little bit different. The initial Co-ords are in Degrees then you have to find a label on the sign that has the cache co-ords in UTM.

ArgusTuft · Post by **ArgusTuft** » 18 October 06 8:11 pm

theUMP wrote:
ArgusTuft wrote:Meridean creep?
Hey! I use a Meridian! (Magellan Meridian Green)
Are you calling me a creep just because I made that crack about Garmins?

If I wasn't using a Magellan Meridean No Colour myself, I would have to say Yes but seeing as how my GPS is so old, I have to take the back off and feed the little cocky that runs around in the tiny little wheel, welllll......

If · Post by If » 19 October 06 7:40 pm

There's only ONE variable in the Geocaching network.... the CACHER

GeoScrubers · Post by **GeoScrubers** » 19 October 06 8:14 pm

GeoScrubers wrote:And why is it that when I went to Greenwich, the GPS showed E/W 00.0000, but I was about 60m from the official meridian

Now that I have all these excuses for failed to find

, does anyone have the "Correct" reason

Even looking at mapsource, the 00.000 line is not at the Greenwich observatory where the physical line is

Map Monkey · Post by **Map Monkey** » 19 October 06 8:56 pm

GeoScrubers wrote: Now that I have all these excuses for failed to find , does anyone have the "Correct" reason

You're not very good at caching

mm

Map Monkey · Post by **Map Monkey** » 19 October 06 9:33 pm

Sorry, my mistake......i misunderstood the question

From the archived "Meridian" Markers cache:

Note: The Greenwich Meridian is defined in several ways, according to the map datum used. There's OSGB, WGS84, NAD27, and a whole host of others. Their locations of where zero degrees longitude differ slightly (by up to a hundred metres east or west). The WGS84 datum, for example, will often show the Meridian markers to be about 100 metres west of 0Ã‚Â°0.00' in the UK, because the sign or marker was placed there using the OSGB (Ordnance Survey Great Britain) map datum.

HTHs

mm

LazyLeopard · Post by **LazyLeopard** » 19 October 06 11:41 pm

Now that I have all these excuses for failed to find , does anyone have the "Correct" reason Even looking at mapsource, the 00.000 line is not at the Greenwich observatory where the physical line is

The short answer is that WGS84 is based on approximations and best-effort measurements, and at Greenwich it happens to be a bit "off".

A longer answer (which details some of the fudges and approximations which went into defining things) can be found at the ROG website here: http://www.nmm.ac.uk/server/show/conWebDoc.416

GeoScrubers · Post by **GeoScrubers** » 20 October 06 8:39 am

map monkey wrote:
GeoScrubers wrote: Now that I have all these excuses for failed to find , does anyone have the "Correct" reason
You're not very good at caching

mm

That's a whole different subject altogether

Thanks for the info and thanks Lazy Leopard for the website.

Geocaching Australia

Caching Topics A to Z # 23 WGS84/Deg Min.Dec/UTM

Where did the equator go ?