IOTA didn't consider that good enough, and they also wanted elevation accurate enough to allow for the height of the observing equipment off the ground. This was before the dithering of satellite signals was discontinued, and you could only get GPS coordinates within a couple of hundred feet. Many years ago I inquired with the International Occultation Timing Association about possibly timing a particular grazing occultation (the Moon occulting Spica), since I happened to live right on the path and could observe it from my backyard. Even then, you may be off by several meters. It may require repeated tries, each time letting the receiver sit undisturbed for many minutes, to let it settle to an almost-steady value. Latitude and longitude within a few meters are easy to derive, but accurate elevation is another matter. I got my coordinates from several tries with a GPS receiver. But if you're like me, you want to know your coordinates to the millimeter, if you can achieve it. Anything within, say, 50 miles is easily good enough for that purpose. Usually a 500-kilometer/300-mile radius is more than sufficient for the initial alignment of the average GOTO scope.Īs another poster has pointed out, you don't need to be very accurate for go-tos. Do you really want to give the whole world the precise coordinates of all of your precious and expensive gear? I would suggest instead that you round or truncate those coordinates to the nearest ten kilometers/miles, more or less.Īnd for the most part (except if you have a modern Meade GOTO mount and you want to track satellites) GOTO scopes don't need nearly that kind of precision to function correctly. Just a point to consider if you plan to publish your precise coordinates on the Internet. There are a number of different coordinate representation systems that have been developed to solve various cartographical problems over the years and advanced GPS's actually allow you to pick between them. Most (not all) GPS's will display your precise Lat/Lon coordinates to the nearest ten meters/yards or so.īe advised that just because they differ, it doesn't mean that one of them is wrong.
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