Wikipedia:Featured article candidates/Crab Nebula

Crab Nebula
The spectacular result of a colossal explosion, and one of the most intensely studied of all nebulae. Its article had a cleanup tag on it two weeks ago - I hope it now does the nebula justice, and I offer it here for your consideration. Worldtraveller 14:31, 17 May 2006 (UTC)
 * Excellent article... especially considering the versions 2 weeks ago. I have a few minor concerns from a non-science-person's perspective, but like I say they're minor and I have no real qualms about supporting this article.
 * Could use a bit more context for total non-science people, who would be reading an FA. Insufficently explained terms and phrases like "progenitor star", "Doppler shift of spectral lines in its optical spectrum", etc. can just be a bit daunting to someone interested in the topic, but without a science background.
 * "the nebula's brightness can be used to create maps of X-ray emission" The paragraph makes this sound important but it doesn't really go on to explain why it is. Just kind of left me curious. --W.marsh 15:10, 17 May 2006 (UTC)
 * Thanks for your comments, W. - I added an explanation of progenitor, and clarified the doppler shift bit (hopefully). How does it look?  Any more terms need explaining?  I am pondering how best to address your second comment - will do so shortly.  Worldtraveller 16:10, 17 May 2006 (UTC)
 * Yes, it looks better, just to make it formal, Support. --W.marsh 14:45, 18 May 2006 (UTC)
 * Thanks! I just added a sentence to hopefully make clear what occultation mapping has been important for.  Worldtraveller 22:43, 18 May 2006 (UTC)

Here are examples from the top.
 * Object for the moment: 2a. Needs a clean-up. Support.
 * "Recent analyses of the available historical records"—can you analyse unavailable records?
 * Simple year-link? See WP's policy.
 * ly should be spelt out on first occurrence, even if it is linked. Why is it linked again, and why is it spelt out further down? Disorganised.
 * "The Sun's corona was mapped in the 1950s and 1960s from observations of the Crab's radio waves as they pass through it"—tense problem: "passed"?
 * "blocked out X-rays"—remove "out"?
 * Provide metric equivalent for inches.
 * Chinese and Arab astronomers in 1054 become Chinese and Japanese in the next section.
 * "Tracing the expansion back revealed that the nebula must have been expanding"—repetition; can it be avoided here?

Plus lots more throughout. It's a good article, lavishly illustrated with images. It should be fixed now. — Preceding unsigned comment added by Tony1 (talk • contribs)


 * Well, I was copyediting while Tony wrote that. Some were fixed anyway; others I have dealt with, but "lots more throughout" is not helpful. -- ALoan (Talk) 15:42, 17 May 2006 (UTC)
 * Thanks for the comments, Tony, and thanks very much, ALoan, for a thorough copyedit which addressed most of them before I'd even read them. I've addressed the rest now, except for two.  Year linking is not something which need be avoided at all costs, and I think linking to a year like the year in which the supernova was first seen is valuable - it's interesting to read what else was happening in the world at the time.  Also, Recent analyses of the available historical records to me conveys the sense that there are not a large number of historical records available.  Omitting 'available' makes it sound like there are lots of historical records.
 * You say there are lots more throughout - any chance you could list them? I've been reading this article daily for about two weeks and could probably not even spot a major spelling error now.  Worldtraveller 16:10, 17 May 2006 (UTC)


 * Support - Well done. I have copyedited a little. -- ALoan (Talk) 15:35, 17 May 2006 (UTC)
 * Support. A good article. RyanG e rbil10 19:23, 17 May 2006 (UTC)
 * Support Very very nice. Also nice to see an astronomical article with some new pics to me (rather than just the few commonly seen Hubble images, a wide range of stuff). Staxringold 19:31, 17 May 2006 (UTC)
 * Support looks good. It is as it always was T 21:33, 17 May 2006 (UTC)
 * Oppose Image:Filaments in the Crab Nebula.jpg has no source. Jkelly 02:33, 18 May 2006 (UTC)
 * I forgot to give the URL when I uploaded it. It's there now.  Worldtraveller 08:30, 18 May 2006 (UTC)
 * Objection removed—Thanks for your editing, ALoan; I've further copy-edited it, although reviewers are not obliged to do so, as you know. Your comment that '"lots more throughout" is not helpful' implies that to assert in this room that Criterion 2a is not satisfied requires every instance of poor prose throughout the article to be cited; if that were the case, reviewers wouldn't bother critiqueing prose, and poorly written FACs would pass through unchallenged. Providing examples should, don't you think, be the standard for prompting the original contributors to improve their whole text, and by providing further examples (at random, as it were) to ultimately assert failure to meet 2a, if that is the case?


 * To take up Wordtraveller's point about 'the available historical records', well, no, it doesn't imply what you intend it to. What about 'the few historical records that are available', or 'the few records from that period'? After reading your point about 1054, I'll go back and relink it.


 * One more query: "Titan's X-ray 'shadow' was larger than its solid surface, due to its atmosphere"—Can you explicated the mechanism; the cause is currently unclear (was it because light bounced off/was absorbed by Titan's atmosphere?)


 * Well done, Worldtraveller—it is a lovely article.


 * Tony


 * Thanks for your editing and comments, Tony. I thought probably a rephrase would be best for the historical records bit - I'll do that now, and will clarify the Titan thing, which I've got sounding unnecessarily complicated.  Worldtraveller 08:30, 18 May 2006 (UTC)
 * Sorry, Tony; perhaps I was shorter than I needed to be. I appreciate that a FAC reviewer is under no obligation to contribute: on the other hand, styles and tastes vary; and having read and copyedited an article once, it is easy to fix specifics, but a bit difficult to know what to do when someone says that there are "lots more" to be fixed. But at least we got there in the end. (Does "lovely article" count as support, btw? ;)-- ALoan (Talk) 08:53, 18 May 2006 (UTC)
 * Oppose: too short, not comprehensive. Everyking 05:22, 18 May 2006 (UTC)
 * What's missing? Worldtraveller 08:30, 18 May 2006 (UTC)
 * Not to be too critical, but see below. Our page is much nicer, in terms of prose, than SEDS, though. -- ALoan (Talk) 17:21, 18 May 2006 (UTC)
 * Support A nice article, well-balanced with images. Missing inf. are years and data on major observations and discoveries (like e.g. here), and I am very disappointed with that. But as other similar featured precedents exist, like Cat's Eye Nebula, I consider that to be my personal preference and don't object to this article's possible featured status. BTW, since 1970 until Chandra's discoveries one part in the north of the nebula (see also ) was a big mystery. There is even its photo in O III in the Soviet 1990 5-vol. "Physical Encyclopedia". I should suggest (not require!) to mention that mystery somehow in the article. Cmapm 16:41, 18 May 2006 (UTC)
 * Oh! The SEDS page is great - can we have just a little bit more detail, please? -- ALoan (Talk) 17:21, 18 May 2006 (UTC)
 * We do already have years of some observations (Bevis, Messier, Rosse) but I've added some more to give a sense of the history of Crab studies. I'll look into the mysterious jet and see what I can add.  Thanks for the comments!  Worldtraveller 22:42, 18 May 2006 (UTC)
 * Double plus support - excellent stuff. I saw a Compton gamma ray image on Commons - worth adding that the Crab is one of the brightest gamma ray sources in the sky? -- ALoan (Talk) 10:26, 19 May 2006 (UTC)
 * Managed to squeeze in a reference to gamma rays. Worldtraveller 23:26, 19 May 2006 (UTC)
 * Support Nice article.--Dwaipayan (talk) 18:49, 18 May 2006 (UTC)
 * Support &mdash; Nice article, although the history section is not quite as developed as in the SEDS article. To be consistent, the text and the table should show the same distance and dimension. For example, in one place it is listed (accurately) as 6,300 ly, while the table and introduction show 6,500 ly. Also there is no margin of error listed. It would have been nice to have a paragraph on telescope observation of the nebula for amateur observers. Otherwise it looks good. &mdash; RJH 22:32, 19 May 2006 (UTC)
 * Well spotted! I've made all the distances consistent now.  I'm not sure about the margin of error - I'm not sure if a meaningful value exists.  The Trimble paper cited for the distance gives ±110pc, but that's purely a statistical value from 12 numbers.  The 12 numbers themselve each have their own margins of error, not taken into account in calculating the final value.  I tried to write something about observing it with small telescopes but it didn't sound very good - I'll try to work up something decent tomorrow.  Worldtraveller 23:26, 19 May 2006 (UTC)
 * Great article. Support. Miss Madeline | Talk to Madeline 22:46, 19 May 2006 (UTC)
 * Support. While the SEDS page is very detailed, the detail can be excessive; I believe the article has reached an appropriate compromise between comprehensiveness and trivial details, by listing only the most historically-significant observations. Everything else in the article clears out, and it certainly meets the criteria. Tito xd (?!? - help us) 09:31, 20 May 2006 (UTC)
 * I think a great many readers would like access to those "trivial details" that are being willfully omitted. Notice how he plays the old game of "well, what's missing?" in response to my objection, as if I know anything about the Crab Nebula to be able to meaningfully respond to him. This article shouldn't be featured until someone else with a good knowledge of the subject can vouch that it is thoroughly comprehensive&mdash;featuring the article without this kind of review would be admitting a very low standard for a FAC, and if it was a more accessible subject I think that would be glaringly obvious to everyone. Everyking 10:22, 20 May 2006 (UTC)
 * If you know nothing about the Crab, why on earth would you say with such certainty that this article is not comprehensive? Wouldn't you first do some basic research to see what else might need to be included, so you can tell the authors what more to put in?  Worldtraveller 10:51, 20 May 2006 (UTC)
 * All right, so you're telling me this says everything there is to be said about the Crab Nebula that is even remotely notable (by my definition)? What about these "Crab studies" you referred to? It sounds to me like there's a rich and extensive body of research on this nebula which can't possibly be represented by this short article. Anything studied extensively enough to have a "study" associated with it should be quite long and have a number of subarticles as well. Everyking 03:43, 21 May 2006 (UTC)
 * By studies, we mean scientific papers. What subarticles should there be?  You're really not helping by not telling me what you think is missing.  Worldtraveller 12:59, 21 May 2006 (UTC)
 * Yeah, I know what you mean. Everyking 14:39, 21 May 2006 (UTC)
 * Support. Looks really good. Seems to have appropriate level of detail without becoming too technical or too long. — Cuivi é  nen T, Saturday, 20 May 2006 @ 22:52 UTC
 * Comment. Worldtraveller has done a nice job with this article, but have a minor suggestion. In the "External links" section there are a couple red links.  If SEDS should have an article, I suggest one be created.  Otherwise, remove the wikilinks. --Aude ( talk | contribs ) 12:44, 21 May 2006 (UTC)
 * Thanks for the comment - I'll do SEDS a stub article now as I think they do warrant an article. Worldtraveller 12:59, 21 May 2006 (UTC)