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#1
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You're totally stupid. The fact is the Sun moves across the sky
at the very same speed all the time it moves across the sky. Are you so stupid that you actually think the Sun speeds up as it nears the horizon? Bwahahahahahahhahahaha! S.Simon "Jeff Morris" wrote in message ... Once again, you're proving you've never actually taken a noon sight. By claiming its just the same as a sunset you demonstrate your ignorance. At sunset, the Sun is moving at its fastest apparent velocity - it's dropping at over 10 arc-seconds per second, about one arc-minute every 5 seconds. At local noon, its "hanging" near its highest point, varying less than one arc second for almost two minutes. Anyone that has plotted even one noon sight knows this. Even if you had one arc-second accuracy, you could still be off 30 miles, In fact, your accuracy is about 100 times worse than that. The only way to get an even approximate longitude with a noon sight is to take many sights, and plot a curve. Ten minutes would not be a long enough time - maybe 30 minutes would give you a lone enough time span. Your claim that the "sun only stays at it's azimuth for one second" is meaningless. There may be only an instant as the sun makes its meridian passage, but determining this point can't be done as you suggest. But you don't have to take my word for it - even though I worked as an astronomer for 6 years, programming celestial navigation for a $250,000,000 spacecraft. I admit shipboard navigation is a bit different. Perhaps someone else can arbitrate. "Simple Simon" wrote in message ... "Jeff Morris" wrote in message ... Once again Neal has blown a chance to impress. If he had made a reasonable claim, it might have been believable. But by claiming the impossible, he proves that he really knows nothing of celestial. comments interspersed ... "Simple Simon" wrote in message ... One sight at local noon yields your latitude and longitude. Clearly not true - for starters, you can't take "one sight at local noon" unless you already know your longitude. If Neal had actually ever taken a Noon Sight, he would know this! Hey, dummy! Celestial is based heavily on dead reckoning. Longitude can be pretty closely gleaned by dead reckoning using only one noon sight per day. The more accurate your dead reckoning the less time you have to sit on the house bringing old sol down to the horizon and checking if your angle is getting larger (patience), has stabilized (fix) or is getting smaller (you missed it) Local noon is local noon is local noon. One needs only an accurate watch to time when the sun is at noon. The tables then tell you your longitude when this angle and time occurs and the offset from GMT. It seems to me that YOU are the one lacking in working knowledge of noon sights. Poor Ole Thom who claims to have used a sextant seems to not understand this simple fact. 1) the angle of the sun at local noon gives you your latitude. 2) the time differential of the sun's azimuth from Greenwich mean time gives you the longitude. True, but its a very tedious process for even an approximate position. It can't be done with "one sight." Yes it can. That's the beauty of the noon sight. One sight does it all. Expensive chronographs are no longer necessary. This has been true for almost a century. GPS time is plenty accurate enough Well, duh! as well as a good quartz watch set to radio signals from WWV. Even a cheap quartz watch will do. I can take one noon sight anywhere in the world covered by the tables I have on board, correct it for errors and come up with my position within ten miles easily every time provided it is not overcast, raining or some such. Nonsense. The "zenith distance" of the Sun varies less than one second for almost two minutes at local noon. During this time the Earth moves about 30 miles at the Equator. And that's with one second accuracy! One minute accuracy is considered pretty good - that might leave you 100 miles away. Celestaire says Neal's plastic sextant typically has a 5 minute error. And Neal is claiming he can do this with one sight! While it is possible to do this for latitude, it is completely impossible for longitude. You are completely wrong. One accurate local noon angle of the sun is ALL that's needed. The sun only stays at it's azimuth for one second. A sight can be taken with a one or two second accuracy which is good enough to place one in the ten-mile range which is all a sailor of a small sailboat really needs. Look at a sunset sometime. Tell me you cannot mark the exact second the bottom limb touches the horizon. I can so you should be able to. I don't know about your sextant buy mine allows me to create a sunset at noon as I adjust the vernier. It is easy to tell when the sun touches the horizon and then goes the other way. PUTZ! I can tell you are one of these arrogant people who wish to muddle up the ease of a noon sight so you can claim you do something magic with your sextant. It simply ain't so. Any old fool can take a noon sight and ascertain their position with great accuracy. S.Simon |
#2
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That's why I said "apparent velocity." As I said, the apparent velocity
changes dramatically, from being very fast near the horizon, to hanging almost motionless at noon. Basic stuff, but its enough to prove that you've never done a noon sight. See my response to Wally - it has the reference from Bowditch. But its pretty clear you have no desire to actually learn this stuff; you thought nobody would call your bluff. "Simple Simon" wrote in message news ![]() You're totally stupid. The fact is the Sun moves across the sky at the very same speed all the time it moves across the sky. Are you so stupid that you actually think the Sun speeds up as it nears the horizon? Bwahahahahahahhahahaha! S.Simon "Jeff Morris" wrote in message ... Once again, you're proving you've never actually taken a noon sight. By claiming its just the same as a sunset you demonstrate your ignorance. At sunset, the Sun is moving at its fastest apparent velocity - it's dropping at over 10 arc-seconds per second, about one arc-minute every 5 seconds. At local noon, its "hanging" near its highest point, varying less than one arc second for almost two minutes. Anyone that has plotted even one noon sight knows this. Even if you had one arc-second accuracy, you could still be off 30 miles, In fact, your accuracy is about 100 times worse than that. The only way to get an even approximate longitude with a noon sight is to take many sights, and plot a curve. Ten minutes would not be a long enough time - maybe 30 minutes would give you a lone enough time span. Your claim that the "sun only stays at it's azimuth for one second" is meaningless. There may be only an instant as the sun makes its meridian passage, but determining this point can't be done as you suggest. But you don't have to take my word for it - even though I worked as an astronomer for 6 years, programming celestial navigation for a $250,000,000 spacecraft. I admit shipboard navigation is a bit different. Perhaps someone else can arbitrate. "Simple Simon" wrote in message ... "Jeff Morris" wrote in message ... Once again Neal has blown a chance to impress. If he had made a reasonable claim, it might have been believable. But by claiming the impossible, he proves that he really knows nothing of celestial. comments interspersed ... "Simple Simon" wrote in message ... One sight at local noon yields your latitude and longitude. Clearly not true - for starters, you can't take "one sight at local noon" unless you already know your longitude. If Neal had actually ever taken a Noon Sight, he would know this! Hey, dummy! Celestial is based heavily on dead reckoning. Longitude can be pretty closely gleaned by dead reckoning using only one noon sight per day. The more accurate your dead reckoning the less time you have to sit on the house bringing old sol down to the horizon and checking if your angle is getting larger (patience), has stabilized (fix) or is getting smaller (you missed it) Local noon is local noon is local noon. One needs only an accurate watch to time when the sun is at noon. The tables then tell you your longitude when this angle and time occurs and the offset from GMT. It seems to me that YOU are the one lacking in working knowledge of noon sights. Poor Ole Thom who claims to have used a sextant seems to not understand this simple fact. 1) the angle of the sun at local noon gives you your latitude. 2) the time differential of the sun's azimuth from Greenwich mean time gives you the longitude. True, but its a very tedious process for even an approximate position. It can't be done with "one sight." Yes it can. That's the beauty of the noon sight. One sight does it all. Expensive chronographs are no longer necessary. This has been true for almost a century. GPS time is plenty accurate enough Well, duh! as well as a good quartz watch set to radio signals from WWV. Even a cheap quartz watch will do. I can take one noon sight anywhere in the world covered by the tables I have on board, correct it for errors and come up with my position within ten miles easily every time provided it is not overcast, raining or some such. Nonsense. The "zenith distance" of the Sun varies less than one second for almost two minutes at local noon. During this time the Earth moves about 30 miles at the Equator. And that's with one second accuracy! One minute accuracy is considered pretty good - that might leave you 100 miles away. Celestaire says Neal's plastic sextant typically has a 5 minute error. And Neal is claiming he can do this with one sight! While it is possible to do this for latitude, it is completely impossible for longitude. You are completely wrong. One accurate local noon angle of the sun is ALL that's needed. The sun only stays at it's azimuth for one second. A sight can be taken with a one or two second accuracy which is good enough to place one in the ten-mile range which is all a sailor of a small sailboat really needs. Look at a sunset sometime. Tell me you cannot mark the exact second the bottom limb touches the horizon. I can so you should be able to. I don't know about your sextant buy mine allows me to create a sunset at noon as I adjust the vernier. It is easy to tell when the sun touches the horizon and then goes the other way. PUTZ! I can tell you are one of these arrogant people who wish to muddle up the ease of a noon sight so you can claim you do something magic with your sextant. It simply ain't so. Any old fool can take a noon sight and ascertain their position with great accuracy. S.Simon |
#3
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Hey Pieman,
You've really turned yourself into "Mincemeat" this time. Sorry but had to call you on your 5 minute Noon Sight. It is the easiest sight to make but it does take time; and it should. It is the best sight of the day. Don't screw around with it, for the novices. You have been beaten down to your, "Waterline" don't say anything more or you'll drown. If you want to further demonstrate you're ignorance start talking "star sights" Ole Thom |
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