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A news item involving Five-hundred-meter Aperture Spherical Telescope was featured on Wikipedia's Main Page in the In the news section on 27 September 2016. |
@ 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)
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)
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 dR = 2 RF 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 dV = 2 RV sin(40°) = 205.7 m. The partial spherical cap reflector has a collecting area of approximately 1 km2 and a depth of H = RF (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)
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)
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)
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.
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)
@ 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)
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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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.
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)