Dec. 14th, 1972 last train to leave the moon? [Though that is 2 days beyond the 12th.]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Bingo

My 'today +/- 1' was the range they were on th moon, I saw they landed on the 11th, stay for 74 hours therefore I thought they left before the 14th, my fault there.

Your go

[edit] PS. Did the Pittsburgh hint help

Yes, I found it applied to Apollo 13 and started checking dates from there.

I'm on the run but will come up with a question soon.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Ok, I am going on memory but I think I am right about this....

The unaided human eye is good to about one arc minute of resolution.

Which astronomer was first to break this limit and what did he use?

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Apollo 17 becomes the sixth manned craft to land on the Moon - 11 December 1972.

[Edit: Dagnammit! I missed the next page of posts!! Again!!!]

No. I just went to Wikipedia and looked up events for December 11, which I guess I could have done several days ago.

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- Learn a lot teaching others.

What is it that improves resolution?

What instrument choices do you have?

What other tools are useful?

About when would ths have taken place?

[It's still fun to bludgeon even as the quizzer!!! ]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Is the Moon involved?

The wall quadrant was the first accurate measuring device for stellar declination. Abul-Wafa invented it in 970, Al-Tusi improved it and Tycho Brahe used it to get accuracies better than 5 arc-seconds.

Correct on Tycho Brahe. It is his birthday this week at 460 years.

However, 5 arc seconds sounds like "bad astronomy". It would be cool if they could have gotten it somehow, however. I'll gladly announce you the winner if Abul-Wafa can be shown as having obtained such resolution. I think 5 arc seconds would require about a 25mm aperture using the Rayleigh limit. The eye is about 5 to 7 mm, depending on how young you are.

Otherwise, the rest of the answer I await.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Hint,

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

George

I haven't found the accuracies of the wall quadrant yet, but did find this

http://www-history.mcs.st-andrews.ac...Tusi&CONTEXT=1

Abu Mahmud Hamid ibn al-Khidr Al-Khujandi was the first person to use seconds on a scale (for a sextant) ca 994. He used this to calulate the latitude of the city of Rayy as 35 degrees 34' 38.45". This is correct to the nearest minute. In view of this it suggests that a passable attempt at sub-minute observations was made nearly 600 years before Brahe.

This is certainly interesting, but it is too unlikely that he could obtain such accuracy unless he had extremely unusual eyes or used optics.

From your link...
"Al-Khujandi says that the Indians found the greatest obliquity of the ecliptic, 24 degrees ; Ptolemy 23 degrees 51' ; himself 23 degrees 32' 19".

There is, however, an error in al-Khujandi's value for the obliquity of the ecliptic; it is about two minutes too low. "

He missed the true value by about 6 arc minutes, which indicates his use of arc seconds may be useless, although, admittedly, the ecliptic is not an observed object. It also shows this document is more a historical account rather than a scientific account since they did not realize the degree of error. [bad pun, sorry]

I derived a simple equation for the variation in the obliquity of the ecliptic. The range varies from 24.5 deg. to 22.1 deg. every 41,000 years (ignoring the tiny tidal nutations). Thus the equation for the phase angle is... 1.2[cos(a)] + 23.3. Around the year 994, the phase angle difference would have been 8.87 deg. (360*1010/41000). We are currently at a phase angle of 82.82 deg., so back then it would have been 73.95 deg. for the equation.

This produces an obliquity in the year 994 AD of about 23deg 38min. This is 6 arc minutes greater than his 23deg 32min. Ptolemy, around 150 AD, should have seen an ecliptic of 23deg 47min but stated 23deg 51min, so was off by 4 minutes. So, assuming I'm correct, Ptolemy was more accurate.

His, Abu Mahmud Hamid ibn al-Khidr Al-Khujandi, work is very impressive, but I can not imagine his accuracy exceeding the eye's limit.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

To quote Wesley

"the accuracy of Tycho's instruments. Those tested are the mural quadrant, revolving wooden quadrant, revolving steel quadrant, astronomical sextant, and equatorial armillary, the last measuring declinations directly. Aside from occasional periods when one or another instrument was distinctly out of adjustment - as, by the way, only a study of this kind can show - the observations have errors falling mostly between about 0.5' and 1.0', that is, about the accuracy of the standard used for comparison. Thus, as was also the case in the earlier study of fixed stars, Kepler's belief that Tycho's observations could be trusted to better than two minutes is amply confirmed."


So I suspect the answer you were looking for would be Tycho, with an equatorial armillary.

Nice, ozark1. But there is a reason he could claim 0.5 arc minute. He did not obtain this degree of accuracy with every object likely due to the effort necessary to obtain this improved accuracy.

Don't forget to consider what is in the hint.

You're almost there.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

I suppose you want the answer that Tycho Brahe was the first astronomer to correct for atmospheric refraction. This means that he would be the first "accurate" astronomer.

That said the resolution has to be related to precision rather than absolute accuracy. I suspect Tycho was the first astronomer to get it right but others before him achieved similar degrees of precision but not accuracy

Another great attempt. Precision, however, refers to the accuracy of the instrument, I think, and not in math results.

The hint mentions how the HiZ team was able to beat Perlmutter’s team. What advantage did their color filters really give them? Combine this answer with the math thought.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

ozark1 is correct with Tycho Brahe, thus, no optics are involved. So how did he improve his accuracy? [It might be possible Al-Khujandi did the same, but I have never read about it, so I'm sticking with Brahe.]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.

Tycho's three big innovations were

1) Build as big as you can
2) Get rid of parallax in the measuring sights
3) Using a method for subdividing scales beyond the smallest graduation

He also used redudant observations and had tables to correct for atmospheric refraction.



The only mention of Filters and Tycho was the use of BV narrow band filters to improve measurements against atmospheric differential refraction. Unfortunately this is a modern innovation.

Yes, this will get you down to where the eye is the limiting instrument.

Yes, a fixed eye is better than two in this case. [I think this is what we are talking about.]

Individual arc seconds should impress both benefactor and operator.

Oooh, you are very warm here.

But this would only get him back, at best, to the eye's resolution limit, I think. Of course, another impressive feat nonetheless.

[Yes, though now I wonder if anyone every did consider using colored glass.] What is it about the filters that made the difference? Or, what came next once the filter data was known? [You're almost there.]

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.