Categories

# where am i?

My GPS just told me that the middle of the nearest road intersection to my house has the following coordinates:

lat=43.73066, lon=-79.26482

What does that mean? Since latitudes are positive north from the equator, and longitudes positive east of the prime meridian, that means I’m at 43.73066°N, 79.26482°W. This is what it looks like on a map:

If I wanted to put on airs, I’d quote the location in degrees, minutes and seconds of arc. These units are a bit fiddly to calculate (a minute being 1/60th of a degree, and a second 1/60th of a minute) but are traditional and compact. You can cheat, and put the location into Google Maps and it’ll spit out the DMS coordinates, or you can work it out:

```43.73066°N
43°
.73066 × 60 = 43.8396′
43′
.8396  × 60 = 50.376″
50″

79.26482°W
79°
.26482 × 60 = 15.8892′
15′
.8892  × 60 = 53.352″
53″
```

So, 43° 43′ 50″ N, 79° 15′ 53″ W it is. (I’ve used prime and double-prime characters as I think it looks neater, and it shouldn’t confuse smart quotes).

So that’s my location, relative to somewhere else. I guess one could take a theodolite sextant, learn how to use it, and see (roughly) how far north I am. Longitude’s tricky, and when I first visited Greenwich I really thought that they’d discovered the physical 0° meridian there, and how convenient was it that it was so close to London’s docks! (See, this blog’s not called Numpty’s Progress for nothing.)

But degrees don’t really tell me how far you are from something, and the surface of a not-quite sphere is inconvenient to map onto a flat surface. So from now on, I’m going to look around me as if my surroundings are flat.

## 2 replies on “where am i?”

[…] … but those coordinates don’t look anything like the degrees we had yesterday. We have to convert back to unprojected decimal degrees with my old friend, proj. If we store the […]

[…] take the coordinates 43.73066°N, 79.26482°W from my first entry. I will make a single point shapefile with this […]