Talk:Five-hundred-meter Aperture Spherical Telescope

Decimal vs. DMS coordinates

@Phoenix7777: To expand on that edit comment: if you work through the math, the source decimal coordinates correspond to those DMS values exactly, but with extra digits of excessive precision added. Using the DMS values represents them exactly, but without a stupid number of digits. Since the center of a telescope is a useful location to know, I don't mind a bit more precision than the 500 m diameter might imply, but 6 digits is 10 cm accuracy, which is silly, as the source values are obviously 1′′ = 30 m accurate values. (The conversion, of course, is justified by WP:CALC.) 71.41.210.146 (talk) 23:20, 4 July 2016 (UTC)

Er... I may have to retract that. The source I cited gives the location as "N25.647222° E106.85583°", which is 25°38′49.9992″N, 106°51′20.988″E. You used 25.652950 N 106.856495 E, which is different. Where did that value come from? The source needs updating if that's the correct value. (The same coordinates also appear in [1], which is why I trusted it) 71.41.210.146 (talk) 23:26, 4 July 2016 (UTC)

I got the value from the Google map. If you don’t like the resolution, just reduce it. The current Coord is out side of the site. My Coord is the center of the site. Apprently your edit is wrong.―― Phoenix7777 (talk) 23:40, 4 July 2016 (UTC)

Sorry, I thought you were going back to the decimal form in the reference. I don't mind you fixing it if it's wrong, but then we need to update the <ref> correspondingly. My problem is that Google maps is just showing me "Sorry, we have no imagery here" at that location, which makes it hard to check. Seeing if I can find a workaround for that... 71.41.210.146 (talk) 23:55, 4 July 2016 (UTC)

I don’t think the city of Orlland is censoring the map although some countries are. Try zooming out the map, then you may be able to see the map.―― Phoenix7777 (talk) 00:13, 5 July 2016 (UTC)

It was my browser plugins not talking to the new tile servers; they are (by design) deeply suspicious of google servers. Fixed. You're right, and footnote updated accordingly. 71.41.210.146 (talk) 00:30, 5 July 2016 (UTC)

Maximum zenith angle: 40° or 26.4°?

All of the early documents talk about a 40° maximum zenith angle, but p. 8 of a recent paper Jiang, Peng; Nan, Ren-Dong; Qian, Lei; Yue, You-Ling (29 Apr 2015). "System solutions study on the fatigue of the fast cable-net structure caused by form-changing operation". arXiv:1504.07719 [astro-ph.IM]. on the structural engineering of the deformable primary says "According to the design principle of the reflector system, the edge of the cable net is fixed on the ring beam. The illuminated region cannot extend beyond the 500-meter diameter, and the maximum observation zenith angle is 26.4 degrees. The trajectory of the illuminated aperture is thus limited to within a certain region near the reflector center."

Can anyone confirm that this is an official change to the telescope's capabilities? I'm inclined to believe it, as it's a more recent paper and this is exactly the sort of thing that tends to happen between initial planning and the final result, but I'd like to discuss it here first. 71.41.210.146 (talk) 11:46, 6 July 2016 (UTC)

Diameter: 500 m or 520 m?

Another case where more recent documents contradict earlier design documents. Williams, R.L. II (July 2015). Five-Hundred Meter Aperture Spherical Radio Telescope (FAST) Cable-Suspended Robot Model and Comparison with the Arecibo Observatory (PDF) (Report). Ohio University.

On p. 4 it says quite explicitly:

“ The planar partial spherical cap of the reflector has a diameter of d_R = 2 R_F sin(60°) = 519.6 m (length of 4.9 futbol pitches) at "ground" level. This diameter is 1.7 times the Arecibo diameter. It is significantly (4%) larger than the 500 m claimed in the name "FAST". The planar partial spherical cap of the virtual focus surface has a diameter of d_V = 2 R_V sin(40°) = 205.7 m. The partial spherical cap reflector has a collecting area of approximately 1 km² and a depth of H = R_F (1 − cos(60°)) = 150 m. ”

This is based on a 300 m radius and an opening angle of exactly 120°. The information is apparently copied from Fig. 9 on p. 98 of Li, Hui; Zhang, Xinyu; Yao, Rui; Sun, Jinghai; Pan, Gaofeng; Zhu, Wenbai (8 September 2012). "Optimal Force Distribution Based on Slack Rope Model in the Incompletely Constrained Cable-Driven Parallel Mechanism of FAST Telescope" (PDF). In Bruckmann, Tobias; Pott, Andreas (eds.). Cable-Driven Parallel Robots. pp. 87–102. doi:10.1007/978-3-642-31988-4_6. ISBN 978-3-642-31988-4.

This seems implausible to me, because such a spherical cap with radius 300 m and height 150 m would have an area of 282743 m². Dividing that into 4455 equilateral triangles (there are 5 missing at the bottom, as seen in all the pictures), each one would have an area of 63.47 m² and a side of 12.1 m. This contradicts the 11 m dimension quoted often in recent completion news articles. On the other hand, assuming a diameter of 500 m implies a sagitta of 134.17 m, a total area of 252902 m², a per-triangle area of 56.77 m², and a triangle side of 11.45 m, which at least rounds to 11. Also, for the purpose of that paper, the shape and size of the dish is unimportant. Only the shape and size of the focal surface matters, and for that the only important dimension is the radius of curvature (300 m) and focal length (140 m) Any other opinions? 71.41.210.146 (talk) 22:25, 6 July 2016 (UTC)

http://fast.bao.ac.cn/en/overview.html may or may not be helpful. All the best: Rich Farmbrough, 21:07, 28 September 2016 (UTC).

Name

If the name is Five-hundred-meter Aperture Spherical Telescope, then this article should be renamed. 85.24.247.24 (talk) 09:03, 25 September 2016 (UTC)

The name is actually Chinese: 五百米口径球面射电望远镜; the English translation is subject to variation, and the presence or absence of hyphens is an awfully minor matter. I won't object if someone wants to rename the article, but MHO is that it's not worth bothering. 71.41.210.146 (talk) 15:24, 26 September 2016 (UTC)

I don't agree that this is a minor point. Almost certainly the parse is: ((((five hundred) meter) aperture) (spherical) telescope). The formal comma between aperture and spherical is often left out when the construction is clear, but the hyphenation of a compound modifier in a multiple modifier sequence is almost never left out in standard English. It's just not done. — MaxEnt 01:11, 29 August 2018 (UTC)

The English website at [2] name it the Five-hundred-meter Aperture Spherical radio Telescope. Stephen 23:25, 27 September 2016 (UTC)

I think it should be either of

* Five Hundred Meter Aperture Spherical Telescope

* Five-hundred-meter Aperture Spherical Telescope

since the Chinese leaves out he word "radio" as I understand it.

Since it is known as FAST the latter is probably better.

All the best: Rich Farmbrough, 20:58, 28 September 2016 (UTC).

Checking multiple sources, it appears that both the hyphens are the word "radio" are used more often than not. Older articles by members of the project (like this 2007 paper) omit both, so the article was named correctly when created, but even though I thin the clarified name is awkwardly long, I reluctantly support updating the article title to include both. 71.41.210.146 (talk) 02:30, 1 October 2016 (UTC)

Wikipedia should follow the weight of reliable sources. The article's name and the first reference in the lede should match. In addition, general readers understand the word telescope, at least without qualification, to mean an optical telescope. Therefore, in my opinion, the title and first reference should include the word radio.—Finell 02:57, 1 October 2016 (UTC)

@Finell: Actually, although I take your point about general readers' understanding, I don't think it applies here. The "...is a radio telescope..." part is right up top, not to mention the "Five hundred meter" part of the name precludes an optical telescope. The "radio" part is only essential where the name is stripped of all other context. That might occur in a link to this page, but it doesn't apply to the page itself. Plenty of other radio telescopes do not include "radio" in the name. Allen Telescope Array, Green Bank Telescope, Lovell Telescope, Karoo Array Telescope, South Pole Telescope, Primeval Structure Telescope, Large Millimeter Telescope, etc. Arecibo Observatory also isn't qualified, nor is the proposed Einstein Telescope, which isn't even electromegnetic.

It's more an application of WP:NAME and WP:OFFICIAL. Given that there are several minor orthographic variants which are equally clear, which do we use? I find over-WP:HYPHENation a curse in normal writing (I got into it at length at Talk:ACCC_conductor#That_hyphen...), and in this case they don't improve clarity; they're only there to make the acronym work better.

So I think "disambiguity" is not a good reason, and I find the current title to be more readable. But "most commonly used" is enough reason to change all by itself. I'm willing to correct obvious chinglish, but this isn't that bad. (Of course, we should have redirects from all four variants, with/out hyphens and with/out "radio".) 71.41.210.146 (talk) 18:18, 1 October 2016 (UTC)

Sources for comparison to a wok?

I heard informally that some Chinese are calling it the world's biggest wok. I have to admit the resemblance is uncanny. Has anyone got a usable source for that? 71.41.210.146 (talk) 05:38, 28 September 2016 (UTC)

Answering my own question... http://mobile.nytimes.com/2016/09/26/world/asia/china-telescope-fast-space-seti.html 71.41.210.146 (talk) 05:59, 28 September 2016 (UTC)

If it had a transmitter, like Arecibo, it might be inviting aliens to "wok this way". All the best: Rich Farmbrough, 20:59, 28 September 2016 (UTC).

Although amusing, I would reject any mention of a wok as un-encyclopedic.—Finell 03:02, 1 October 2016 (UTC)

Well, User:Rich Farmbrough's joke was obviously facetious, but the comparison might be useful to help a reader visualize it. In particular, the diameter to depth ratio (deeper than Arecibo) is very similar to a typical wok. But yes, I haven't actually put it in due to lack of anywhere it fits. 71.41.210.146 (talk) 17:31, 1 October 2016 (UTC)

More seriously

Instead, Nan and his team designed a system that pulls a roughly 300-meter-diameter section of FAST’s spherical reflector into a subtle parabola, while positioning receivers along the parabola’s axis. “It’s like forming a smaller bowl within a big wok,” Li says.

http://www.sciencemag.org/news/2016/09/world-s-largest-radio-telescope-will-search-dark-matter-listen-aliens

All the best: Rich Farmbrough, 18:49, 1 October 2016 (UTC).

Meter vs. metre

I don't know if this (Chinese) article must use American English or British, but whatever you choose, it must be consistent; and the page (name) must be moved accordingly. Cheers, BatteryIncluded (talk) 14:16, 29 September 2016 (UTC)

The unit should use the most common unit, meter.——星耀晨曦 14:39, 29 September 2016 (UTC) — Preceding unsigned comment added by 星耀晨曦 (talk • contribs)

@星耀晨曦: Within English the unit of measure is spelled as either "metre" or "meter" depending on if it's a British English or American English publication. News articles from British English speaking parts of the world call it the "Five hundred metre Aperture Spherical Telescope"^[3][4][5] On Wikipedia we use both forms of English but try to stick to one form within a Wikipedia article with the form used depending on the topic of the article.

I would go with with the American English "meter" for this article as that's the form used on http://fast.bao.ac.cn/en/ which is the English version of the official FAST site. --Marc Kupper|talk 22:32, 3 October 2016 (UTC)

Thank for you explain! You reading this type of article, it not bother you？——星耀晨曦 (talk) 20:10, 4 October 2016 (UTC)

@星耀晨曦: Could you clarify the question? What about reading it would bother anyone? 71.41.210.146 (talk) 00:51, 5 October 2016 (UTC)

South China or Southwest China?

@Bob103051: Re: This edit changing "southwest China" to "south China". You're right there's a lot of China to the west of that location, but Southwest China has an official definition, and Pingtang County and Guizhou Province are both in it. I'm inclined to put it back, but it's hardly urgent so we can discuss it. What do you think? (I'm reminded of the non-obvious definition of the region called the Southern United States, which includes Delaware and Maryland, but excludes Arizona & New Mexico.) 71.41.210.146 (talk) 07:36, 3 October 2016 (UTC)

After what seems a reasonable wait, I went and undid it. Still open to discussion, however. 71.41.210.146 (talk) 09:52, 15 October 2016 (UTC)

Random observation about Sky & Telescope article...

Do sections of this recent Sky & Telescope article sound like they were inspired by this WP article?

Copying is legitimate anyway, and it's rewritten, but I get the impression the author consulted the WP article for interesting talking points.

This has editorial impact, because if it is cribbed from WP, it's a WP:CIRCULAR reference and I can't use it to satisfy the {{citation needed}} tag on the planetary defense statement in the article. 71.41.210.146 (talk) 19:55, 10 October 2016 (UTC)

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Removed False Claim

There was claim in the introduction which referenced a news article about FAST detections of neutral hydrogen in other galaxies.

https://www.rt.com/news/493811-dark-matter-hydrogen-fast-telescope/

The RT article is nonsense. Neutral hydrogen has been detected in other galaxies using the 21 centimetre line for many decades, this is referenced on other articles. The original press release was pointing out that these were the first extragalactic neutral hydrogen detections by FAST, not ever.

http://www.cassaca.org/en/featured-science/2020/07/the-first-fast-detection-of-neutral-hydrogen-emission-from-extragalactic-galaxies/

I have removed this claim, please don't add this source back into the article. — Preceding unsigned comment added by LazyAstronomer (talk • contribs) 22:37, 2 November 2020 (UTC)