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11Bravo · 04-07-12, 02:09 PM

We are going to compare some calculated and observed sunrise times. The calculated times came from some software, but you can get similar results from this website http://aa.usno.navy.mil/data/docs/RS_OneDay.php. The values are calculated for the positions shown, and are expressed as GMT and as the local Zone Time. Also shown are screen shots of the sub's clocks at each position so you can compare GMT, Zone Time, Mouse Time, and Screen Time.

The sun appears to come from the East of course, so the GMT when it arrives becomes later as your location is chosen further to the West. The calculated GMT's show that nicely in the Table. So we should also expect one of the sub's clocks to show this same trend. ALLLLLLLLAAAAAAAAARRRRRRRMMMMMM!!!

The Screen Time was our hope for being the GMT, but it doesn't show the right trend and it gives plainly wrong answers outside of TZ 00. The Mouse time is even worse.

Now look at the calculated Zone Times for the sunrises. These Zone Times are the local times at the observing positions. The times are simply the GMT - TZ as you would expect from the equation I have plastered over every screen shot.

Looking again at the screenshots of the sub's clocks, we see that the Screen Time now appears to be the local Zone Time! What seemed so certain from before now appears to be completely wrong! How could the Screen Time be the GMT of the sea and the local Zone Time of the sky?

Let's check the sunset times to be sure...

Ugh...same story.

Again, because the sun appears to come from the East, the GMT of a sunset becomes later as the observing position moves to the West. Again, we see this trend nicely in the calculated sunsets. And again, the screen shots of the clocks from our sub show that neither one is the GMT we seek. Instead, the Screen Time is actually the local Zone Time as before.

It is nice that we get good agreement between one of our clock's and the local sunrise and sunsets. It is nice that one of the clocks matches closely with observed celestial evens. But we need the GMT if we are to calculate the positions of stars used for celestial navigation.

Let's see if we can figure this out...

04-07-12, 02:09 PM	#12
11Bravo Medic Join Date: Dec 2006 Location: Error Triangle Posts: 168 Downloads: 157 Uploads: 0	We are going to compare some calculated and observed sunrise times. The calculated times came from some software, but you can get similar results from this website http://aa.usno.navy.mil/data/docs/RS_OneDay.php. The values are calculated for the positions shown, and are expressed as GMT and as the local Zone Time. Also shown are screen shots of the sub's clocks at each position so you can compare GMT, Zone Time, Mouse Time, and Screen Time. The sun appears to come from the East of course, so the GMT when it arrives becomes later as your location is chosen further to the West. The calculated GMT's show that nicely in the Table. So we should also expect one of the sub's clocks to show this same trend. ALLLLLLLLAAAAAAAAARRRRRRRMMMMMM!!! The Screen Time was our hope for being the GMT, but it doesn't show the right trend and it gives plainly wrong answers outside of TZ 00. The Mouse time is even worse. Now look at the calculated Zone Times for the sunrises. These Zone Times are the local times at the observing positions. The times are simply the GMT - TZ as you would expect from the equation I have plastered over every screen shot. Looking again at the screenshots of the sub's clocks, we see that the Screen Time now appears to be the local Zone Time! What seemed so certain from before now appears to be completely wrong! How could the Screen Time be the GMT of the sea and the local Zone Time of the sky? Let's check the sunset times to be sure... Ugh...same story. Again, because the sun appears to come from the East, the GMT of a sunset becomes later as the observing position moves to the West. Again, we see this trend nicely in the calculated sunsets. And again, the screen shots of the clocks from our sub show that neither one is the GMT we seek. Instead, the Screen Time is actually the local Zone Time as before. It is nice that we get good agreement between one of our clock's and the local sunrise and sunsets. It is nice that one of the clocks matches closely with observed celestial evens. But we need the GMT if we are to calculate the positions of stars used for celestial navigation. Let's see if we can figure this out... __________________ "Sounds of terror are in his ears; While at peace the destroyer comes upon him." -- Job 15:21 Last edited by 11Bravo; 04-07-12 at 05:43 PM.