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== Colin Henshaw as co-discoverer ==

A statement was added that Colin Henshaw was co-discoverer of the supernova. I'd never seen that claim before, and in searching for that, I found the following [http://amazingspace.org/resource_page/210/stars_stellar_evolution/type set of slides] claiming that. However, that set of slides references [http://amazingspace.org/resource_page/210/stars_stellar_evolution/type this] web page from the space telescope institute, which explicitly cites only Ian Shelton as discoverer. I've reverted the change until we can find a contemporaneous and reliable source with the claim. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 19:37, 24 March 2017 (UTC)
:I further find [http://journals.co.za/content/mnassa/46/5-6/AJA00248266_3121 this] reference (in June 1987), which lists observations of SN1987A, listing Colin Henshaw as one of the observers, which specifies that he discovered the supernova independently. But I can find no reference to an IAU telegram from Henshaw, which is the usual qualification for discovery of supernova. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 19:48, 24 March 2017 (UTC)
::And lastly, the AAVSO provides [https://www.aavso.org/vsots_sn1987a this] history specifying Shelton in Las Campanas as the discoverer also mentioning Duhalde at the same location and Jones in New Zealand. No mention of Henshaw. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 20:10, 24 March 2017 (UTC)

Hi!

I find some links. 

http://www.manastro.co.uk/2011_09.pdf

https://books.google.hu/books?id=cRv4Kro_krUC&pg=PA16&lpg=PA16&dq=1987a+colin+henshaw&source=bl&ots=9DIq9j1gSr&sig=0B_pbwPVVJ4jjdxd1pBhLCM0Kvs&hl=hu&sa=X&ved=0ahUKEwjbq5TMl_HSAhVGCZoKHRSzAM8Q6AEINzAE#v=onepage&q=1987a%20colin%20henshaw&f=false

http://adsabs.harvard.edu/full/1988PASAu...7..352M

http://albireo.percek.hu/archiv_AlbireoBiblio_146_191.html

The original publication is:

Quarterly Journal of Royal Astronomical Society. 28 (4) 533-534. 1987 December.
https://books.google.hu/books?id=KVqmniPg_SMC&pg=PA135&lpg=PA135&dq=1987a+colin+henshaw&source=bl&ots=0eLKg91AmM&sig=Akay73HbnGYpxk643KD5mnpn_sM&hl=hu&sa=X&ved=0ahUKEwjbq5TMl_HSAhVGCZoKHRSzAM8Q6AEIGzAA#v=onepage&q=1987a%20colin%20henshaw&f=false

Unfortunately, the original publication is not available on the web. [[User:Misib2|Misib2]] ([[User talk:Misib2|talk]]) 08:06, 25 March 2017 (UTC)
:Ah. Mystery explained. <i>...noted and photographed the supernova [...] but was in no position to send a report for days</i>.  As I understand discovery attribution, he does not qualify as a co-discoverer - the whole point of discovery is that the rest of the astronomical community is '''told''' about the event in time to do something about it. Notice McNaught in Australia is also not credited with being a co-discoverer. The timeline McNaught gives also precludes Henshaw from discovery - Henshaw was only preparing for observations at the time McNaught was already confirming location on photographic images. 
:I'll note that the Manchester Astronomical Society slides were an announcement of a presentation by Henshaw - the listing as "joint discoverer" undoubtedly came from him saying he was.
:That Henshaw discovered it independently is not in doubt, but credit as co-discoverer doesn't seem to apply in this case because he did it in a vacuum after other people had already discovered it and communicated the discovery. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 16:14, 25 March 2017 (UTC)

You are not a source. Cynthia A. Steinke book is a source. So it is not your decision. Your opinion does not count !! Give me a source which support your opinion. [[User:Misib2|Misib2]] ([[User talk:Misib2|talk]]) 16:41, 25 March 2017 (UTC)
:Essentially every source I find lists Shelton, not Henshaw. E.g., [https://www.aavso.org/vsots_sn1987a this]. 
:As a secondary comment, please understand the policy at [[WP:BRD]]. You were bold, you were reverted, now we must discuss, *Before* you re-instate your edits. See [[WP:3RR]] on not re-reverting again.
:My above explanation is indeed opinion, expressing my understanding of how different sources could be presenting different comments. Note that none of the accounts I've seen list him as "co-discoverer" (meaning sharing credit), at most he's listed as having independently discovered the supernova. But because he didn't notify anyone, he does not get credit as discoverer. The timeline in the McNaught account is pretty definitive that he observed the supernova '''after''' <s>South Africa</s> Chilean and New Zealand observatories were actively confirming the already-announced discovery. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 17:18, 25 March 2017 (UTC)

Would you please read the following article.

Henshaw, Colin: The independent discovery of SN 1987 in the LMC, from Zimbabwe. Quarterly Journal of Royal Astronomical Society. 28 (4) 533-534. 1987 December. [[User:Misib2|Misib2]] ([[User talk:Misib2|talk]]) 06:22, 26 March 2017 (UTC)
:I would except (a) I don't have access to it, and (b) independent discovery is not the same as co-discovery. McNaugh documented that when Henshaw observed SN1987A, Chilean and New Zealand observatories were confirming their discovery, which they had already reported to the IAU bureau of telegrams. It's admirable that Henshaw made his own discovery independently, but the fact that it was independent was because he was out of the loop, not because he had priority. As best I can tell, he does not deserve credit for co-discovery.
:At this point, we seem to have reached an impasse. Since nobody else seems to be participating in the discussion you can seek dispute resolution in a variety of ways; One of the easiest is [[WP:THIRDOPINION]], which will bring in an independent volunteer to offer an opinion. You could also try [[WP:DRN]] (Dispute resolution noticeboard) or create a [[WP:RFC]] (request for comment) which will bring in other interested parties.
:As a side issue, copying a warning I put on your talk page to my talk page serves no purpose. The [[WP:3RR]] template serves merely to inform you about the edit warring policy, and to document that you have been informed if it comes to administrator action. Copying that to my page, since I was the one who warned you, is irrelevant - I obviously already know the policy and any administrator will simply find it comical. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 07:23, 26 March 2017 (UTC)

Well! For the sake of the readers of this discussion may I ask you to summarize the date and the time of all our known independent observeries, please. Thanks in advance. [[User:Misib2|Misib2]] ([[User talk:Misib2|talk]]) 08:07, 26 March 2017 (UTC)

:I'm here. I'm the one who posted the <nowiki>{{citation needed}}</nowiki> tag because obviously the claim required a reliable external publication to confirm. There are reliable external publications documenting, so far as I can tell, fairly reliably who saw what and when. Is it beyond the wit of man (or at least Wikipedia editors) to summarise what those publications say without adding spin or bias? [[User:Lithopsian|Lithopsian]] ([[User talk:Lithopsian|talk]]) 14:00, 26 March 2017 (UTC)
::I'm happy with adding somewhere in the body an account of Colin Henshaw making an independent discovery along with the circumstances that caused him to be unaware of the fact that it had already been discovered and reported before he even made his observations. What I'm not happy with is crediting him in the lede with the discovery. I'm very concerned with [[WP:CIRCULAR]], and that simply changing the "discovered by" to "Shelton and Henshaw" would distort the historical record. Independent discovery is not co-discovery (where credit is shared). As best I can tell, the references which call Henshaw as joint discoverer (as opposed to independent after-the-fact discoverer) are ones where that description comes from Henshaw. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 15:19, 26 March 2017 (UTC)
I believe the definitive record is the IAU CBAT [http://www.cbat.eps.harvard.edu/iauc/04300/04316.html circular] from 24-February. The sequence of events and timeframes:
* Feb 24.23 - Image found on photograph started at 24.06 in Chile.
* Feb 24.27 - Jones in New Zealand observes
* Feb 24.454 - Moreno and Walker in New Zealand obtain images.
* Feb 24.455 - McNaught in Australia observes.
* Feb 24.9 - Menzies in South Africa observes.
Note that Henshaws's observations would have been about this time (Feb 24.9), although he didn't report them; the simple geometry of earth rotation meant that Zimbabwe was in daylight when Chile and New Zealand observations were made. It's interesting that he made an independent discovery (as did Jones and probably thousands of amateur astronomers), but he doesn't get the credit discovery. [[User:Tarl_N.|<span style="color:green;">'''Tarl N.'''</span>]] ([[User talk:Tarl N.#top|<span style="color:teal;">discuss</span>]]) 16:05, 26 March 2017 (UTC)
:Thanks. [[User:Misib2|Misib2]] ([[User talk:Misib2|talk]]) 10:52, 27 March 2017 (UTC)
:C Henshaw is '''only''' person to make claim for co discovery. No corroboration from other source at all. No reliable verify for claim ever and must be ignore. No reputable astronomer accepts the co discover claim. [[User:Jastronomer|Jastronomer]] ([[User talk:Jastronomer|talk]]) 10:00, 3 November 2017 (UTC)

== Mass of progenitor ==

I don't see the mass of the progenitor listed anywhere here. This page [https://www.aavso.org/vsots_sn1987a] suggests it was about ~18 Solar M(o). [[User:Fig wright|Fig]] ([[User talk:Fig wright|talk]]) 14:58, 17 August 2020 (UTC)
:We don't really know. What we have is guesses. E.g., Initial ~20 solar masses, from [https://arxiv.org/abs/astro-ph/0611544 here] (reference in [[Sanduleak_-69_202]]). This works backwards from spectral class and luminosity, as has low confidence. [[User:Tarl_N.|<b style="color:green">Tarl N.</b>]] ([[User talk:Tarl N.#top|<span style="color:teal">discuss</span>]]) 15:37, 17 August 2020 (UTC)

== Non-circumstellar rings ==

There is a good deal of discussion of the cause of the inner ring around the star, but none of the two rings overlapping one another that are not centred around the star.

What is the cause of those extra two rings? Also, there are two very bright stars and one less-bright reddish star on or nearly on the two rings.  Are they coincidental near stars that merely happen to be on the path to the supernova?
[[User:VictoriaWordNerd|VictoriaWordNerd]] ([[User talk:VictoriaWordNerd|talk]]) 23:19, 18 August 2020 (UTC)

:The two "outer" rings are actually centred on the star, but we see the system at an angle.  The rings are the tips of an hourglass of material ejected from the progenitor star before it exploded, and now highlighted by the supernova explosion.  I agree this is not explained well in the article.  There are a number of papers discussing the origin of the rings.<ref>{{cite journal |bibcode=2011A&A...527A..35T |title=The outer rings of SN 1987A |last1=Tziamtzis |first1=A. |last2=Lundqvist |first2=P. |last3=Gröningsson |first3=P. |last4=Nasoudi-Shoar |first4=S. |s2cid=56105807 |journal=Astronomy and Astrophysics |year=2011 |volume=527 |pages=A35 |doi=10.1051/0004-6361/201015576 |arxiv=1008.3387 }}</ref>  The two stars on the rings are probably not related, although they may well be LMC stars.  Although they appear bright in deep images, they are about 15th magnitude.  There are other, fainter, stars even closer to the supernova location, again not related so far as we know.  [[User:Lithopsian|Lithopsian]] ([[User talk:Lithopsian|talk]]) 14:20, 19 August 2020 (UTC)
{{talkref}}

== remnant ==

Does it really not have a name other than 'SN 1987A remnant'? It's a [[planetary nebula]], right? [[User:Arlo Barnes|Arlo James Barnes]] 09:49, 13 July 2022 (UTC)
:It's not a [[planetary nebula]], it's a [[supernova remnant]].  Not surprising really since it was created by a supernova.  If you're looking for a snappy name like ''Supermag'', you're out of luck.  All the designations I'm aware of, and there are quite a few, have both letters and numbers in them, with the possible exception of ''LMC SN'', which Simbad lists but which I've never seen being used.  [[User:Lithopsian|Lithopsian]] ([[User talk:Lithopsian|talk]]) 13:16, 13 July 2022 (UTC)

== James Webb Space Telescope planned observations ==

The JWST is scheduled to observe SN 1987A for 7 1/2 hours on 2022-07-16 UTC. I don't have recent editing experience; would one of you care to add this to the article? The source is https://www.stsci.edu/files/live/sites/www/files/home/jwst/science-execution/observing-schedules/_documents/2219603f02_report_20220715.txt , which is linked to by https://www.stsci.edu/jwst/science-execution/observing-schedules &mdash; [[User:Wdfarmer|Wdfarmer]] ([[User talk:Wdfarmer|talk]]) 20:51, 15 July 2022 (UTC)

: Nifty news, thanks! But given that's going to be tomorrow, we probably don't have to update the article (per [[WP:NOTNEWS]]) until the observations have been made. Although this ventures into [[WP:CRYSTALBALL]], I would assume that some form of image release will happen shortly thereafter, which would make an ideal opportunity to update the article. [[User:Tarl_N.|<b style="color:green">Tarl N.</b>]] ([[User talk:Tarl N.#top|<span style="color:teal">discuss</span>]]) 21:02, 15 July 2022 (UTC)

:: The observing run [https://www.stsci.edu/jwst/science-execution/program-information.html?id=1232 is complete], but you won't necessarily see anything about it for a while.  The researchers will have the raw data, but are unlikely to produce anything printworthy until they have a paper ready to publish.  As far as I can tell, the raw data is not available publicly, although it might well be once the research team have published.  [[User:Lithopsian|Lithopsian]] ([[User talk:Lithopsian|talk]]) 13:14, 17 July 2022 (UTC)

::: https://arxiv.org/abs/2307.06692[[User:文爻林夕|文爻林夕]] ([[User talk:文爻林夕|talk]]) 22:45, 23 July 2023 (UTC)

:::: https://phys.org/news/2023-08-webb-reveals-iconic-supernova.html [[User:Arlo Barnes|Arlo James Barnes]] 00:18, 1 September 2023 (UTC)
::::Still only preprint, submitted but not accepted yet.  The image can be included though, very nice.  The paper is very detailed; I haven't read the whole thing yet, but can probably use it for some updates in the last two sections.  [[User:Lithopsian|Lithopsian]] ([[User talk:Lithopsian|talk]]) 13:23, 1 September 2023 (UTC)