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Current Version: 1.2 (01/12/2023)
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The Purpose | The Application | The Details
(double-click any word to see its definition)
"Satellite Finder Online (JavaScript)" (hereafter SFJ) is a Web-based version of my popular Java application "Satellite Finder". This service provides coordinates to help you locate geostationary satellites, primarily for those installing and pointing satellite dishes. If you are a professional dish installer and you expect to be in the field at the time you need pointing information, you may want to download "Satellite Finder" as well (both services are free).
To use SFJ, in most cases you don't really need to enter any information — the program will use network resources to approximate your location, print a map and set the program's geographical location entry fields. For satellite dish alignment, this approximate position is nearly always more than adequate.
To enter a custom position, for example to create a satellite pointing table for a location other than your own, either zoom and click the map, or type in a geographic position and click "Compute".
There is more complete documentation below the application.
Select a location with this map (powered by OpenStreetMap and Leaflet):
Awaiting network location ...
(your browser may ask your permission
to provide this information)
Or type in a position, then press "Compute":
Here are the results (full explanation below):
SFJ solves a problem becoming more important as we become more reliant on satellite communications. Basically, there is now a ring of very expensive jewels circling the earth in a special orbit. Science-fiction writer Arthur C. Clarke first had the idea that a particular altitude would cause a satellite to appear motionless to the revolving earth below. That orbital height, about 22,300 miles, perfectly balances a satellite's orbital velocity with the earth's rotational velocity. This means we can install satellite dishes that point to particular locations in the sky, and the satellites won't drift out of view.
Because all the satellites lie directly over the equator, and because they are all at the same altitude, the mathematics required to produce viewing angles is relatively simple. In fact, the challenges in the design of this page lay more in the area of designing an automated way to locate your computer and printing an orientation map, than in computing satellite pointing angles.
Remember these rules:
If you elect to enter a geographical position, remember the entries can be expressed in decimal degrees, or degrees and decimal minutes, as shown in these example entries for 40° 12.5' north:
If you choose to make a single decimal degree entry as in the second example above, be sure the minute value is set to zero.
Turning now to the data table, the columns are:
"Az(t)": The true-North azimuthal angle for the satellite at the chosen site. The Azimuth represents a horizontal circle measured in degrees:
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