NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Lunars Almanac Data (was Re: In the spirit...)
From: Frank Reed CT
Date: 2004 Oct 28, 16:52 EDT
From: Frank Reed CT
Date: 2004 Oct 28, 16:52 EDT
Dan A wrote:
"Yes, but Steven's format is nearly perfect for printing, and his data can be
taken with you on a laptop and used without an internet connection."
I'm sure you know this, but in case it hasn't occurred to other people following along, you can print or save locally any web page. Let's say you want to do some lunars out in the wild or at sea. You're going to be out for two weeks. Go to my web site, select each date for those two weeks, and when the date is displayed, select "File", "Save As..." in your web browser. They're now saved locally on your computer and you no longer need an Internet connection. You could do this for any period from 1750 to 2050. The saved files contain only the data and the table format with no calculational overhead and they load more or less instantly even on devices with very simple web browsers.
Although it's NEVER going to matter, I should mention for the "attentive detail-watchers" that pages saved in 2004 for the year 2040, as an example, should be considered suspect because the value of delta-T for that year is not yet known. On the other hand, anyone clever enough to realize this should also be clever enough to know how to use the data with minor adjustments even then!
And wrote:
"Frank's web pages are not stand-alone self-contained JavaScript either, like Henning
Umland's pages."
I *could* put together a stand-alone version (for a price) but it would take up several megabytes of disk space. Understand that Umland's scripts produce rather low accuracy data. Lunar distances from his calculator are not to be trusted, and I think he notes that, too. They are typically ten times less accurate than those generated in Steve Wepster's tables or on my web site, and for historical lunars considerably worse. On the other hand, if you want to experience lunars as they were historically, maybe you really should use bad almanac data! The errors that arise from using the standard algorithms for the Moon's position (following Meeus, as in H. Umland's scripts) are about the same as were typical in the almanacs 200 years ago.
And concluded:
"As regards to dead reckoning, I use my memory: I-15 North, I-84 West, I-82
West, I-90 West, I-5 North. Done!"
Aha. I must investigate these I-# roads further. They sound like an excellent method of traditional non-electronic navigation. <g>
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"Yes, but Steven's format is nearly perfect for printing, and his data can be
taken with you on a laptop and used without an internet connection."
I'm sure you know this, but in case it hasn't occurred to other people following along, you can print or save locally any web page. Let's say you want to do some lunars out in the wild or at sea. You're going to be out for two weeks. Go to my web site, select each date for those two weeks, and when the date is displayed, select "File", "Save As..." in your web browser. They're now saved locally on your computer and you no longer need an Internet connection. You could do this for any period from 1750 to 2050. The saved files contain only the data and the table format with no calculational overhead and they load more or less instantly even on devices with very simple web browsers.
Although it's NEVER going to matter, I should mention for the "attentive detail-watchers" that pages saved in 2004 for the year 2040, as an example, should be considered suspect because the value of delta-T for that year is not yet known. On the other hand, anyone clever enough to realize this should also be clever enough to know how to use the data with minor adjustments even then!
And wrote:
"Frank's web pages are not stand-alone self-contained JavaScript either, like Henning
Umland's pages."
I *could* put together a stand-alone version (for a price) but it would take up several megabytes of disk space. Understand that Umland's scripts produce rather low accuracy data. Lunar distances from his calculator are not to be trusted, and I think he notes that, too. They are typically ten times less accurate than those generated in Steve Wepster's tables or on my web site, and for historical lunars considerably worse. On the other hand, if you want to experience lunars as they were historically, maybe you really should use bad almanac data! The errors that arise from using the standard algorithms for the Moon's position (following Meeus, as in H. Umland's scripts) are about the same as were typical in the almanacs 200 years ago.
And concluded:
"As regards to dead reckoning, I use my memory: I-15 North, I-84 West, I-82
West, I-90 West, I-5 North. Done!"
Aha. I must investigate these I-# roads further. They sound like an excellent method of traditional non-electronic navigation. <g>
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
