How to Find Your Latitude and Longitude

One way to determine your city's latitude and longitude is to use the Interactive Sky Chart itself. Click the "change" button next to the word "LOCATION" just below the Interactive Sky Chart logo. The next screen you see, entitled Choose Location, will contain the fields shown at left. For a city in the USA or Canada, fill out the first (top) part of the form and click SUBMIT. For a city in any other country, fill out the second part of the form and click SUBMIT.

The next screen, entitled Choose Time Zone, will report your city's latitude and longitude, as shown at right for Toledo, Ohio. Write down the latitude and longitude (both in degrees and arcminutes) and, while you're at it, make a note of the two-letter state/province abbreviation (in this case, OH) and country code (in this case, US) that appear to the right of the city name.

Now convert the latitude and longitude to decimal degrees; simply divide the arcminute value by 60 (because there are 60 arcminutes in 1 degree) and add the result to the degree value. For Toledo, Ohio, we get latitude = 41 + (40/60) = 41.67°N and longitude = 83 + (34/60) = 83.57°W. What about the sign? Use + for N latitude and E longitude, and – for S latitude and W longitude. So for Toledo, Ohio, we have lat = +41.67 and lng = -83.57.

You can also find the latitude and longitude of almost any city on Earth by following the links from WorldAtlas.com.

Time Zone and DST

If you're not sure of your time-zone offset in hours west (–) or east (+) of UT (Universal Time, essentially the same as Greenwich Mean Time), use the Time Zone pull-down menu on the Choose Time Zone screen. Note that this menu shows standard time, which is what we want. The example at left shows that Eastern Time (Toledo's time zone) is 5 hours west of UT, or timezone = -5.

If daylight-saving time is being observed, then dst = on. If not, dst = off. Note that this cannot be determined automatically — you have to set it manually. This means that if you build a link when DST is in effect, you'll need to modify it later when your area reverts to standard time (or vice versa), and again when DST goes back into effect, etc. Sorry about this little inconvenience!

Another good source of worldwide time-zone and DST information is the World Clock.