Talk:Sednoid

Known members

The final sentence of the "Known members" section refers to a dozen objects with a > 150 au, q > 30 au, and ω = 340°±55°. In the article this sentence is kind of out of place, since there is no immediately obvious reason for its inclusion in the article. Presumably it was included because Trujillo & Sheppard's article on the Sednoids posits that this larger population of objects share a common origin with the Sednoids. What do you think about following the last sentence of the "Known members" section with a sentence like

• Some astronomers have suggested that these objects share a common origin with the Sednoids.^[1][10]

In addition, the Jilkova/Leiden Observatory paper refers to this larger set of a dozen or so objects as "Sednitos". The "Sednitos" terminology appears to be unique to that particular paper. If the final sentence is expanded to include the sentence I suggest above, maybe it should also be followed with a sentence like:

• Some astronomers^[10] refer to this family of objects as "Sednitos".

I have elected to not add these two sentences since the "Some astronomers" phrasing is awkward and I am unsure of the significance of the idea that they share a common origin. —RP88 ^(talk) 15:24, 20 June 2015 (UTC)

Discovery of third known sednoid

At the TNO2018 conference, Scott Sheppard has announced the discovery of a third Sednoid with a 3-opposition arc, q = 65 AU, Q ≈ 2000 AU, a ≈ 1100 AU, currently 83 AU from the Sun. I am almost certain that this is V774104. I tried to investigate, with mixed success (see here and here for some relevant discussion; confirming that V774104 is a sednoid, but that there is a confusion about the identity/name). I am unsure how to refer to it in the sednoid article. V774104 already calls that object a sednoid (based on Sheppard's statement from January and the email correspondence with David Tholen), but I haven't included the details from TNO2018 yet. Mostly because I am still not 100% certain that there aren't just two new sednoids: V774104, and the one presented at the conference. --Renerpho (talk) 21:19, 30 March 2018 (UTC)

References

I'd probably counsel waiting until we have a reasonable source to reference before attempting to add it to this article. Eventually we will have a preprint or a news article at an astronomy news site that we can use. Oh, and by the way, your attempt to ping likely failed since notification will only work successfully if you sign your post in the same edit in which you link to their user page. See Help:Fixing failed pings. —RP88 ^(talk) 01:51, 31 March 2018 (UTC)

Agreed, thanks RP88! Tagging Kheider and Exoplanetaryscience again. 😊 --Renerpho (talk) 02:05, 31 March 2018 (UTC)

Unfortunately, doesn't seem we can really do much with that information until they do release that data, which they seem to plan on doing soon. exoplanetaryscience (talk) 04:12, 1 April 2018 (UTC)

The reference seems to be a misunderstanding: it has been written in the S&T-article of V774104, but the data provided is consistent to that of the new TNO with q = 65 au, d = 83 au and Q ~ 2000 au. For further details please see my comment here -- Ralfkannenberg (talk) 22:02, 10 April 2018 (UTC); correction -- Ralfkannenberg (talk) 22:15, 10 April 2018 (UTC)

I suggest to add the new likely sednoid already now, as there are controverse and misleading discussions in the internet and this object is already listed in the article's table. This table provides a good overview at the first glance, but some text also should be provided. I have emphasized that the data is preliminary. - I further suggest to add also V774104 into this table although it is most likely no sednoid, but as said this table provides an excellent overview at the first glance and I think it is worth to support this. For this purpose some columns should be added as well. I'll have a look in my lunch break. -- Ralfkannenberg (talk) 08:35, 11 April 2018 (UTC)

done -- Ralfkannenberg (talk) 10:24, 11 April 2018 (UTC)

References

V774104 and 2015 TG387 are the same right?

J mareeswaran (talk) 04:11, 2 October 2018 (UTC)

It certainly seems possible, but I can't find any reliable source that identifies these two objects as the same body. —RP88 ^(talk) 05:27, 2 October 2018 (UTC)

Daniel Bamberger is of the opinion that these are not the same body: "Note that, despite some similarities, this is probably not identical with the object known as V774104, another possible new sednoid that received some media attention in 2015..." [1]. —RP88 ^(talk) 05:59, 2 October 2018 (UTC)

Thanks. So there are 3 confirmed sednoids and possibly a fourth one whose orbit is not yet finalised? J mareeswaran (talk) 14:32, 2 October 2018 (UTC)

We have two sednoids which have have been published and subjected to peer-review and one whose journal article is pending (but likely forthcoming soon). The observation arc for V774104 is insufficient to confirm it to be a sednoid. —RP88 ^(talk) 09:42, 4 October 2018 (UTC)

I see I've been quoted here, so I guess I should take part. I'm not sure about the ID, to be honest. I still believe they may not be the same, but there are some inconsistencies:

• V774104 should be in Pisces[2], while 2015 TG387 is in Pegasus (from the known astrometry). EDIT: I checked again; it's actually at the border of Pegasus and Pisces, and on the Pisces side, in the northwestern corner of the constellation. Exactly where V774104 is supposed to be.
• V774104 should be 103 AU from the Sun; 2015 TG387 is "only" 80 AU from the Sun. But Sheppard had said that V774104 may not be as distant as thought, so that's not an argument.[3] There is uncertainty whether he was really referring to V774104 at that time though.
• On the other hand, the discovery image of V774104 published in 2015[4] is the same as the discovery image for 2015 TG387[5].
• There had been some confusion about the identity of V774104 before, and apparently this involves mixing up two or more objects. See discussion at [6], where it had been (somewhat erroneously) identified with another object 2015 TH367. It turned out that 2015 TH367 actually was V774104, and that the distant object announced back in 2015 was not V774104 (but that Sheppard et al. had mixed up their internal designations when preparing the press release). What a mess...

All in all, I think it is very much possible that V774104 is 2015 TG387, and that there is no 4th sednoid. But the identification is far from certain. -- Daniel Bamberger Renerpho (talk) 19:34, 4 October 2018 (UTC)

Quote Mike Brown[7]:

yes, in fact. the unusually high perihelion leads to a very large overestimate of the distance. As I said 2 years ago: it's either the most distant KBO known, or it is actually interesting. Turns out it's interesting.

Tagging Kheider and Exoplanetaryscience again. What do you think?Renerpho (talk) 20:39, 4 October 2018 (UTC)

Regarding the proposal to merge the articles V774104 and 2015 TG387 - I don't think that's a good idea just yet. The evidence that the two are identical is strong, but I'm still only maybe 90% certain about it. I'd like to point to what happened with another object earlier believed to be V774104, 2015 TH367 (see here).
Also, at this point I'd like to point out the issues discussed here, where some questions about the identity of 2015 TH367(sic!) and V774104 were discussed.Renerpho (talk) 00:30, 5 October 2018 (UTC)

One additional problem with the ID: 2015 TG387 never had a data arc of 2 weeks, as claimed for V774104. It was a one-nighter, and then was recovered 7 weeks later, when Sheppard et al. had already made the announcement of V774104.[8] The three observations from 13 October 2015 are enough to pin down its distance to 83±15 AU. While a distance of 103 AU was possible at that time, I don't see why they should have announced it as such. The only possible explanation would be that Sheppard et al. have more observations of the object that haven't been submitted to the Minor Planet Center, which I would find rather puzzling.Renerpho (talk) 11:29, 6 October 2018 (UTC)

Scott Sheppard has discovered both of them, so he should clarify. In March at the TNO-2018-conference, he has referred to both of them. To me it seems more likely that V774104 is a normal SDO with a low perihelion like Eris or (225088) 2007 OR₁₀, which may be of academic interest but currently give no clue to Planet 9 which is in the focus of their research. In the MPC database, there are 272 objects with an aphel > 100 AU and only 3 of them are "Sednoids". Restricting this search to sufficiantly bright objects that can be seen at this distance, there are 22 objects with an aphel > 100 AU and an absolute magnitude <= 5.2; still only 3 of them are "Sednoids", i.e. 19 are ordinary SDOs. So from a probabilty point of view, V774104 is an ordinary SDO and not a Sednoid. -- Ralfkannenberg (talk) 18:43, 6 October 2018 (UTC)

"still only 3 of them are "Sednoids", i.e. 19 are ordinary SDOs." This is wrong as 2015 TH367 is less bright. Thus it is 2 sednoids and 20 ordinary SDOs. - I have checked the Ephemeris of both (M.P.E.C. 2018-T05) and to my surprise they are quite similar, so this idea cannot be excluded that way ... -- Ralfkannenberg (talk) 22:26, 7 October 2018 (UTC)

Furthermore, the absolute magnitude of an object, that was estimated to 4.0 mag at a distance of 103 au, is 5.3 mag at a corrected distance of 78.7 au, as given for 2015 TG₃₈₇. -- Ralfkannenberg (talk) 12:52, 8 October 2018 (UTC)

Yes. As I said, there has never been a 2-week arc for 2015 TG₃₈₇, but using the 3 observations from 13 October 2015, one can fix the distance[[9]] and see what the resulting orbit would be. The distance is barely constrained, and prograde orbits are possible for a distance of 78-93 AU from the Sun (smaller distances require e>1; larger distances require a retrograde orbit). Fixing the Sun distance to 79.9 AU (the actual value) gives H=5.3 mag, a=197 AU, i=11.4°. Fixing it to 103 AU gives H=4.2 mag, a=122 AU, i=169°. Note that this orbit is retrograde. Fitting the single nighter to a prograde orbit at 103 AU would require some of the astrometry to be of bad quality.Renerpho (talk) 18:55, 8 October 2018 (UTC)

I have found the discovery fotos of both of them and I tend to say that they are different:

V774104: https://www.skyandtelescope.com/astronomy-news/v774104-most-distant-solar-system-object-11212015/

2015 TG₃₈₇: https://dtm.carnegiescience.edu/news/new-extremely-distant-solar-system-object-found-during-hunt-planet-x -- Ralfkannenberg (talk) 16:53, 8 October 2018 (UTC)

Those are the images I linked above. They are the same images for both objects (one is zoomed in and cropped, but they show the same object).Renerpho (talk) 18:35, 8 October 2018 (UTC)

In the astronews.com/forum the users come to the same result. I must admit that I am not familiar with such kinds of comparison. Anyway: now we can identify V774104 with 2015 TG₃₈₇ ! -- Ralfkannenberg (talk) 18:38, 8 October 2018 (UTC)

I am still not confident about this. Remember what happened with 2015 TH₃₆₇! Renerpho (talk) 18:55, 8 October 2018 (UTC)

See here. Renerpho (talk) 18:57, 8 October 2018 (UTC)

Mike Brown once has said: "In the Kuiper Belt, things move slowly". So there is no need for any hurry - let us wait until you are confident about this. -- Ralfkannenberg (talk) 21:46, 8 October 2018 (UTC)

Probably not important, but I've found the provisional designation of 2015 TG₃₈₇. It was called V302126 before its announcement by the MPC. See abstract 311.09 in the program for the DPS50 meeting (19-27 October 2018).[10] This does not add much to the discussion, because we already knew that V774104 was the internal designation for 2015 TH₃₆₇, not 2015 TG₃₈₇, and that Sheppard et al.'s original press release from 2015 was in error. Renerpho (talk) 20:24, 19 October 2018 (UTC)

@Renerpho:@Kheider: I've just asked Scott Sheppard and he says that 2015 TG387 is indeed the more distant object- and in fact that they were never wrongly identified in the first place. When he initially mentioned the objects, V774104 (2015 TH367) appeared to be further than V302126 (2015 TG387). Either way, the mystery's been definitely cleared up (in short, yes, 2015 TG387 is "V774104"). I hope that helps. exoplanetaryscience (talk) 08:39, 3 April 2019 (UTC)

@Exoplanetaryscience:@Ralfkannenberg: Thanks. In that light, I am fine with merging the articles, and creating a redirect from V774104 to 2015 TG387. If there are no further o objections, I suggest to start a section on the 2015 TG387 article talk page to discuss how to properly include this mess into the article. I advise to mention it, but to not give it more weight than absolutely necessary. Renerpho (talk) 10:46, 3 April 2019 (UTC)

If Scott has verified they are one and the same (the discovery images look the same), we might as well merge them. We might want to include a footnote that there was confusion as to which minor planet designation V774104 referred to. -- Kheider (talk) 14:08, 3 April 2019 (UTC)

My understanding is that V774104 is 2015 TH367 (non-sednoid q≈30). I believe the Sky&Telescope discovery image of "V774104" is mislabeled and is really 2015 TG387 (V302126;sednoid). Perhaps V774104 should be a re-direct page for both objects. -- Kheider (talk) 20:31, 4 April 2019 (UTC)

Well, yes - in some sense, V774104 is both objects and neither of them, as I understand it. Or maybe it is just one or the other, I'm not entirely sure. Could we please invite Mr. Sheppard to make a public statement about this that is not hearsay? Even if we decided on one way or another, how do we justify that decision? Is there a source for any change made to those pages? I have not seen "private communication" as a reliable source on Wikipedia, have you? One could just as easily say that the status quo (three separate pages not linked to each other) is the only status for which reliable sources exist, be it wrong or not. I see User:Kheider made a WP:BOLD change to V774104 and some of the other pages already. None of those changes is coming with a reliable source yet. Renerpho (talk) 01:48, 5 April 2019 (UTC)

There was already an unreferenced line in V774104 claiming that it is 2015 TG387. As long as we do not state anything too absolute, we can let the reader decide. Doing nothing suggests to the reader that they have not published any further data on this object since 2015. -- Kheider (talk) 13:28, 5 April 2019 (UTC)

@Kheider:@Renerpho: Again really late to the party because I've gotten a lot busier over the last couple of months, but I think we should just go ahead and merge V774104 and 2015 TG₃₈₇ not just because of some communications saying so, but because technically V774104 was never formally announced outside of a quick mention in a press conference. No matter what it's clearly deprecated and shouldn't be listed as a separate object when they've been established to be the same. exoplanetaryscience (talk) 23:28, 8 July 2019 (UTC)

As I understand it, V774104 is 2015 TH367. The media coverage got the nicknames V774104 and V302126 mixed up. -- Kheider (talk) 03:57, 9 July 2019 (UTC)

Yeah, you're right about that. sorry, old habits. Either way, I think it should still go getting merged considering how long it's been. exoplanetaryscience (talk) 19:17, 9 July 2019 (UTC)

What do you want to merge it with? The intial press release that was picked up by the media was about related to 2015 TG₃₈₇, while the object actually called V774104 was 2015 TH₃₆₇. Which article do you want to merge V774104 with? It is about both of these objects, and none of them, because the story contains aspects of both objects. "The media coverage got the nicknames V774104 and V302126 mixed up." -- No, it were the discoverers who mixed them up, not the media. The media never learned of the existence of V302126, and faithfully reported what they were told. As far as I am concerned, the object discussed in V774104 does not exist and never has. Renerpho (talk) 20:32, 9 July 2019 (UTC)

That said - keeping the article as it is doesn't reflect its non-existence, does it? So, Exoplanetaryscience is right, something has to be done. Deleting isn't an option either (the object V774104 may not exist; the topic V774104 certainly does.) Renerpho (talk) 20:35, 9 July 2019 (UTC)

This is a really confusing situation - the object reported doesn't exist (as it is two objects that got mixed up), but the concept does. It's a historical accident. It's another one of those footnotes in astronomy, like Themis or the pre-1980s 330 Adalberta, which was the non-existent 1892 X. I think V774104 should be treated similarly. ― Дрейгорич / Dreigorich Talk 13:52, 10 July 2019 (UTC)

Or we could merge it with one of the two and write about V774104 in the discovery section of either object (or both?), explaining the situation there. I think that would be better than giving V774104 its own article, as it seems that nothing else will be written about V774104 under that name. @Renerpho:@Kheider:@Exoplanetaryscience:@Ralfkannenberg: Your thoughts?

@Дрейгорич: I agree, it should be handled along the lines of those "historical footnotes". This story makes me scratch my head. It would be so much easier if some reliable media had covered the story of this mistake! It would make for a nice story, if only somebody wrote about it. I like doing this myself, but Wikipedia isn't really the place for (original) research. To put it differently: Does this topic (the mix-up and non-existence of V774104) exist outside of Wikipedia? Conversely, does the topic of its identification as any of the two objects exist outside of this encyclopedia? It looks to me like this article talk page has become the primary source at this time. Renerpho (talk) 21:30, 10 July 2019 (UTC)

@Renerpho: Someone earlier (Don't know whether it was on the talk page for V774104 or 2015 TG₃₈₇) mentioned that the discoverer mixed the two up, so we can use that as a source. ― Дрейгорич / Dreigorich Talk 22:13, 10 July 2019 (UTC)

@Дрейгорич: There was a private email from David Tholen to @Exoplanetaryscience: on 14 March 2018 (see Exoplanetaryscience's talk page), quote: "I recieved a response from David. This might get a bit complicated, but V774104 = 2015 TH367. However, the distant object at 103 AU is not V774104. I dont know what the “true” distant object ia, but it is neither V774104 nor 2015 TH367. Apparently when making a press release, Scott Sheppard accidentally referred to it as V774104.". On the other hand, there was a private conversation between Exoplanetaryscience and Scott Sheppard on 3 April 2019 (further up on the Sednoid talk page), quote: "I've just asked Scott Sheppard and he says that 2015 TG387 is indeed the more distant object- and in fact that they were never wrongly identified in the first place. When he initially mentioned the objects, V774104 (2015 TH367) appeared to be further than V302126 (2015 TG387). Either way, the mystery's been definitely cleared up (in short, yes, 2015 TG387 is "V774104")." Who do you like more, Dave or Scott? Apart from that: We can't use private conversations with users as reliable sources. Renerpho (talk) 22:27, 10 July 2019 (UTC)

David Tholen confirms there was a mistake. Scott Sheppard denies it. One says that V774104 is 2015 TH367, the other says it's 2015 TG387. Neither of the two can be quoted on any of it. Isn't it funny? Renerpho (talk) 22:30, 10 July 2019 (UTC)

Alright yeah, this has definitely been pretty confusing, but I can send a copy of the emails if you guys want. Although I can quickly describe what the discrepancy is: While both Dave Tholen and Scott Shepherd were on the team that discovered the objects, only Scott was involved in the press release about V774104. The earlier email that Dave sent me was based on what he believed took place, having not been personally involved, and upon later inquiry recommended I go talk to Scott about it directly, which is what gave the more recent information straight from him. So basically the later message from Scott overrides that and should be taken as the primary source of information here. exoplanetaryscience (talk) 22:37, 10 July 2019 (UTC)

I've just emailed Scott to ask him about this situation actually - I'll let you know if there's a reply. ― Дрейгорич / Dreigorich Talk 22:40, 10 July 2019 (UTC)

@Exoplanetaryscience: Thank you! Adding any clarity is appreciated, and your explanation definitely helped me. I don't know if we can make use of the emails, but I'd be interested to see them. If you can make them available (make sure you are allowed to), please go ahead! @Дрейгорич: Thanks, too. Renerpho (talk) 22:42, 10 July 2019 (UTC)

Just to summarize what Scott has said previously (to see if I understand it right): 2015 TG387 (now at 78 AU from the Sun) is the more distant object. The internal designation of 2015 TH367 (now 90 AU from the Sun) was V774104. This object appeared to be very distant when it was first discovered, maybe at 103 AU. It was 26 mag at that time, and located in Aries. Yet, Scott's press release included an image of V302126, which was 24 mag and in Pisces. By pure coincidence, this object would later turn out to be the very interesting sednoid 2015 TG387, while 2015 TH367 is just an ordinary scattered disc object. Scott says that "they were never wrongly identified in the first place", despite all this, and that 2015 TG387 (the sednoid) is V774104. Am I getting that right? Renerpho (talk) 23:03, 10 July 2019 (UTC)

By the way... I just checked again, using the data we have of 2015 TH367. It never had a 2-week arc. At the time of Scott's press release it was a single nighter. That single night doesn't allow to pin down its distance exactly, but fitting an orbit to it at r=103 AU is impossible. I don't know what object Scott refered to in his press release, but with the information available at the time, there was no way that 2015 TH367 could have been the object he talked about, even if we allow for some aspects of 2015 TG387 to have entered the story (in particular when it comes to the size estimate he gave). As mentioned previously, fitting an orbit at r=103 AU to the other object, 2015 TG387, is impossible, too. Sorry for the rant, but I am really looking forward to find out how this all came about. Renerpho (talk) 23:17, 10 July 2019 (UTC)

Very, very interesting case. It seems that the more we learn, the less we know. ― Дрейгорич / Dreigorich Talk 23:47, 10 July 2019 (UTC)

Here's the email that Scott sent to me on the subject: https://i.imgur.com/Co5GxKS.png some of the confusion about stuff might be my fault, to be fair, so this should give the most direct explanation I think we're going to get about the confusion. exoplanetaryscience (talk) 01:54, 11 July 2019 (UTC)

Oh, this perfectly explains things. So the article shouldn't be merged with 2015 TG387. It should be merged with 2015 TH367. It was all a mistake by the reporters, not the astronomers. Confusion done, I think? @Renerpho: @Kheider: @Exoplanetaryscience: ― Дрейгорич / Dreigorich Talk 05:00, 11 July 2019 (UTC)

@Exoplanetaryscience: Thank you, Sam. That actually makes much more sense now than before! The numbers given by Sheppard (90 and 100 AU, respectively) are possible with the single night tracklets (103 AU is outside the possible range for both, but who knows where the reporters got that from). Scott also confirms that both were single nighters at the time, as I had suspected. The observation arc of 2 weeks given in the news stories on V774104 is unsourced, and simply wrong. Good! That rules out any "conspiracy theories" about unpublished observations. I was also wrong about saying that the media never learned about V302126, and that it was the discoverer's fault rather than that of the reporters. I am sorry for that. Nothing of what I said (or am about to say below) is meant as personal attack towards Sheppard (some harsh criticism - yes, maybe). We were right here to conclude that V774104, as it appeared in the news and in the Wikipedia article, never existed. A redirect from V774104 to any one of the two articles on 2015 TH367 or 2015 TG387 seems inappropriate to me. In my opinion, V774104 deserves its own article; not about an astronomical object, but about a scientific quirk, or a case of science communication gone wrong. There would have been lots of opportunities for Sheppard to set the records straight. For example, at a conference in 2018, where he seems to have mentioned V774104 again, and is quoted for saying that "there is a body at 103 AU and the paper about it is in progress".[11] Or when he spoke to Kelly Beatty of Sky&Telescope in January 2018 (see the same link), now talking about V774104 and 2015 TG₃₈₇ as if they had been the same object from the very beginning. Or the paper and press releases about 2015 TG₃₈₇, when that object was announced as the third known sednoid. Or when Sheppard announced 2018 VG18, nicknamed FarOut, now the most distant object at about 120 AU. (That one is at least 100 AU from the Sun, so calling it the most distant object is a sure thing for once.) Or when a similar case as V774104 was discussed at a recent conference, leading to the announcement of FarFarOut, at 140 AU from the Sun (except that this time there was an actual press release). That object was a single nighter at the time of announcement, and it may end up having the same fate as V774104, turning out to be closer than expected. Sheppard could have mentioned the similarities to V774104 in that presentation, asking for caution. He didn't mention it. See around the 40-minute mark in the presentation video. We could have saved ourselves a lot of time if the miscommunication to the press had been corrected in 2015. If that email had been available 4 years ago. @Дрейгорич: My confusion is gone. I am not entirely sure how to proceed, but I think the situation is clear now. However, I don't agree with your suggested merger of V774104 and 2015 TH367. Renerpho (talk) 05:11, 11 July 2019 (UTC)

One thing's for sure. A rewrite of the article (and also articles where V774104 appears) are in order! ― Дрейгорич / Dreigorich Talk 05:14, 11 July 2019 (UTC)

@Дрейгорич: Yes it is! I see you made an edit to V774104 already. Good to be WP:BOLD, but maybe we should work on it as a draft first, and replace it as a whole. Adding single sentences to the article only adds confusion, and there has been enough of that. Renerpho (talk) 05:27, 11 July 2019 (UTC)

@Renerpho: Well, it seems we're going to have to rely on muddled accounts and less-than-ideal sources for this one due to its very nature. I don't think there's anything we can do about that. We just have to rewrite the article the best we can with the information we know. I'm sorry, Renerpho. ― Дрейгорич / Dreigorich Talk 05:30, 11 July 2019 (UTC)

@Дрейгорич: First thing I do is add WP:DISPUTED to the header of V774104. I am working on that now. From there, we can proceed. Renerpho (talk) 05:32, 11 July 2019 (UTC)

Done. No need to apologise, Dreigorich! - We need to make a start somewhere. Shall we move the discussion to Talk:V774104#Disputed, or continue here? Renerpho (talk) 05:39, 11 July 2019 (UTC)

Let's continue there. ― Дрейгорич / Dreigorich Talk 05:48, 11 July 2019 (UTC)

2013 SY99 near q=50 AU

The body 2013 SY99 appears close to the q>50 limit, JPL 49.96897069451585, and MPC 50.0191258. MPC search here: [12] Should it be mentioned? Tom Ruen (talk) 16:13, 3 October 2018 (UTC)

2013 SY99 doesn't appear to be considered a sednoid. Shepard and his co-authors, who originated the term 'Sednoid' (in presentations as early as October 2013), now refer to those objects that they originally called 'Sednoids' as inner Oort cloud objects. Calling them members of the inner Oort cloud is controversial — Shepard and his co-authors do not appear to have convinced the wider astronomical community to recognize this classification. Wikipedia, in order to avoid taking a position on whether or not these objects are actually inner Oort cloud objects, continues to call them by the more neutral term sednoids (we're in good company — both Nature and NASA, at least until recently, also used the term sednoids). The discoverers of 2013 SY99, Michele Bannister and her co-authors, do not consider 2013 SY99 to be a sednoid/inner Oort cloud object, but rather a Kuiper belt/scattered disc object that has been the subject of diffusion (see [13]). Shepard and his co-authors have also rejected 2013 SY99 as a sednoid/inner Oort cloud object and instead classify it as an extreme trans-Neptunian object (see [14]). At some point I assume Wikipedia's use of the term 'sednoid' will become untenable, hopefully by then reliable secondary sources will have settled on whether or not these objects are inner Oort cloud objects (in which case some of this article's content might be merged into the Hills cloud article), are just "extreme" instances of detached objects, or some other classification. For that matter, if the Planet Nine hypothesis turns out to be true and the orbits of the sednoids have been directly influenced by a new planet, a new classification might be introduced based on the name of the new planet. —RP88 ^(talk) 09:51, 4 October 2018 (UTC)

Thanks! It does seem mentioning as being close but not being included. Tom Ruen (talk) 20:44, 4 October 2018 (UTC)

I made the change, also mentioning that the perihelion will surpass 50 AU in the heliocentric reference frame by 7 October 2018 (two days from now). So, I guess this is a good time for the edit.Renerpho (talk) 01:23, 5 October 2018 (UTC)

Please note that Mike Brown in his discovery paper of Sedna classfies both (148209) 2000 CR105 (q=44au) and Sedna as "Inner Oort Cloud Objects". -- Ralfkannenberg (talk) 14:02, 8 October 2018 (UTC)

For lack of a better name, yes. At the time of that paper (before he came up with his Planet Nine hypothesis, and before the discovery of other extreme TNOs), 2000 CR105 and Sedna were the only known objects outside Neptune's influence. There are more of these now. When Brown&Batygin published their first paper discussing "Planet Nine" (see here), (148209) 2000 CR105 was one of 6 objects that seemed to cluster around a certain argument of perihelion. However, they did not consider (148209) 2000 CR105 to be one of the prime objects used for the search for the hypothetical planet because its semi-major axis is too small. It is now usually considered to be an extended scattered disc object (ESDO) by some, and an extended detached disc object (EDDO) by others - depending on the definition. Anyway, it is one of only a few, see the objects in magenta and orange in this plot. The objects relevant for the Planet Nine hypothesis are those among the EDDO and ESDO that have large semi-major axis, and the sednoids. Neither the ESDO nor the EDDO are usually considered sednoids, but they are considered to be Inner Oort Cloud Objects by some, as you see there. The categories for TNOs are ambiguous! Renerpho (talk) 00:05, 17 October 2018 (UTC)

I also mentioned in the 2013 SY₉₉ article that Johnston's Archive now classifies the object as a sednoid, because q>50 AU and a>150 AU. It does meet the definition, after all, even though further analysis shows it doesn't really belong there. Once again: The categories are ambiguous, and only useful to some extent. Renerpho (talk) 00:13, 17 October 2018 (UTC)

This "q>50 AU"-definition seems to have historical reasons as (148209) 2000 CR105 has a perihelion of ~44.2 au and Sedna one of ~76 au, with the Kuiper Cliff at ~47 au. Thus the definition for Sednoids with q>50 au at this time was very far away from (148209) 2000 CR₁₀₅'s perihelion at 44.2 au. Today we know that there are three further minor planets with orbits similar to 2013 SY₉₉ beyond the Kuiper Cliff, belonging to the same dynamical class, i.e. (474640) 2004 VN112, 2014 SR₃₄₉ and 2010 GB₁₇₄. With these high excentricities > 0.8 they can easily be distinguished from the high-perihelion objects with moderate excentricities which are in a stable resonance with Neptune, i.e. 2015 KQ₁₇₄, 2015 FJ₃₄₅, 2004 XR₁₉₀, 2014 FC₇₂ and 2014 FZ₇₁. -- Ralfkannenberg (talk) 08:19, 25 October 2018 (UTC)

2021 RR205

This asteroid also meets the criteria (a=679 AU, q=57 AU), at least in the nominal orbit. However, with a data arc of 363 days, it currently doesn't appear in the source cited by the article, which requires a data arc of more than 365 days. The data arc is short by two days. Should the source be changed, or 2021 RR205 be left out? We are not including 2013 SY99, but that was easier to justify, given its perihelion of exactly 50 AU. That said, 2013 SY99 is at least mentioned in the lead of this article... Renerpho (talk) 01:19, 23 September 2022 (UTC)