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I have seen Aurora Borealis multiple times. In Canada and U.S. The last were huge white curtains with tinge of green that lasted for hours. I was told it happens quite often at northerly latitudes above 50 deg. BTW Aurora Australis is the southern latitude version. Not seen those.
Enjoyed your discussion on the potential roots of the Samson story.
"A little time, a little trouble, your better day"
Badfinger
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Mine were green and red sheets, dancing all night. Little to no white. It was amazing!
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yup, you don't easily forget it. Amazing that it is very natural.
I guess if you see every night you are lucky but not always as amazed.
"A little time, a little trouble, your better day"
Badfinger
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thank you!
diligent hands rule....
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I have written several ephemerides over the years, the first being for an HP75C, using the 'Low-precision formulae for planetary positions' by van Flandern and Pulkkinen (Astrophysical Journal Supplement Series, vol. 41, Nov. 1979, p. 391-411). The paper provides a good introduction to the general problems of ephemerides, and the stated accuracy of +/- one minute of arc is extremely conservative, and for the current era +/- six seconds of arc is realistic. This ephemeris also calculates the 'First point of Ares', enabling star positions to be computed. I used this method to navigate my small yacht by sextant from Southampton UK to Pireaus Greece, with my worst landfall being one third of a nautical mile out. That was in pre-GPS days.
A more accurate methodology, but also much more compute intensive, is Pierre Bretagnon's VSOP82, subsequently developed and refined to VSOP87. The raw data tables which make the basis for the computations are out there on the web somewhere, I'm sure. When written into a program, it is spritely enough on a PC, but might tax all but top-end mobile devices.
A very good source of foundational information is the US Navy's Nautical Almanac, particularly in the 'Explanatory Supplement', a separate publication. Any year will do. Also, get a thorough understanding of the 'equation of time', as it occurs in just about every ephemeris calculation.
A couple of years ago I rewrote my original HP75C program to run on Android, and expanded it to cover not just the sun, moon, six navigational planets, fifty-eight navigational stars and Polaris, but included all ten thousand stars visible to the naked eye (given very good eyes and excellent viewing conditions ). Even on an old Android phone it runs fast enough to be useful, although the virtual graphical sextant 'scope view is distinctly laggardly when scanning the sky.
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thank you! all these sources are very useful for me.
diligent hands rule....
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You need to understand the file format. I converted their programs from c and doubles, to c# and decimals a few years back. Government software is mostly in the public domain; I tried a few until it matched the observatories and Chinese calendars.
Format of the JPL Ephemeris Files
"Before entering on an understanding, I have meditated for a long time, and have foreseen what might happen. It is not genius which reveals to me suddenly, secretly, what I have to say or to do in a circumstance unexpected by other people; it is reflection, it is meditation." - Napoleon I
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just be curious: why do you check that it meets Chinese calendar?
also I want to convert this astrolog program to C#, but I think it is too complex for my needs...
diligent hands rule....
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#Worldle #386 5/6 (100%)
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https://worldle.teuteuf.fr
process of elimination
"A little time, a little trouble, your better day"
Badfinger
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Wordle 603 4/6
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Wordle 603 3/6
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Wordle 603 4/6
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Wordle 603 3/6*
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And ... either a major crash or a milestone tomorrow:
Played: 374
Win %: 100 (Nope - a rounding error)
Current Streak: 299
Max Streak: 299
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Life should not be a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming βWow! What a Ride!" - Hunter S Thompson - RIP
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Wordle 603 5/6
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Get me coffee and no one gets hurt!
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Wordle 603 3/6
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Jeremy Falcon
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Wordle 603 3/6
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"A little time, a little trouble, your better day"
Badfinger
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...Mrs. Buster Boy!
/ravi
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Where even is he these days? Haven't seen a message from him in...years?
I genuinely miss his contributions.
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I contribute to LVGL ( LVGL - Light and Versatile Embedded Graphics Library[^] ). Your "smart" shopping cart with the little screen on it quite possibly uses LVGL to draw the text and the little buttons and such on the display, just as an example of where it might pop up. A redbox style rental unit would be another area you might see it used. Anywhere you have a little computer with a display, often a touch display there's a fair chance it's LVGL powered.
I wrote some code to bring TrueType support to more devices under LVGL. It already supported TrueType but only on a narrow set of devices. TrueType is anti-aliased vector fonts - nice looking text basically. Now you can run it on quite a few different chips, even "lesser" chips that normally couldn't handle something like that.
The other day, months after I contributed it, someone found an intermittent problem with my font code crashing their device, but only sometimes, and only when used from MicroPython, which I do not use.
I was completely stumped and have been helping another developer try to run this down. Today I get the best message I could have received:
"I found the problem, and it's not in your code"
Woo hoo. They still haven't managed to fix it yet, but it's out of my hands, thank heaven. Some problem with the virtual filesystem thing they wrote for micropython returning inconsistent data from file reads.
I've been losing sleep over this because it was completely stumping me, and since I don't have a MicroPython environment handy, nor any experience with it, I was basically tag teaming remotely with a developer who did have those things. We weren't getting anywhere and I was just about out of moves.
Made my day to hear the bug wasn't mine.
To err is human. Fortune favors the monsters.
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Are there still active AM broadcasters in the US of A?
For digital broadcasting, DAB was rejected in favor of HD Radio, for a number of reasons, one of them that HD could make use of the old transmitters, and you could simulcast digital and analog. How did HD come out? Did it knock FM out, leaving digital-only HD transmission? Or do people still buy FM radios, expecting them to pick up all stations in the area? If so, do the broadcasters still care to offer HD?
Or have listeners in the US of A stopped listening to AM/FM radio broadcasts, going completely to internet based listening?
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Does AM still exist? I dislike broadcasts of any form.
In my car I listen to MP3 files.
But when I'm in my wife car, it's FM.
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I don't listen to Financial Media (FM) or Ad Media (AM), it's commercial with a smattering of music and news thats run in a loop. Music that I didn't like then and care even less for now.
PartsBin an Electronics Part Organizer - An updated version available!
JaxCoder.com
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