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Another new Jovian satellite, and another recovery

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  • Bill Gray
    Hello all, We have a new guy , S/2017 J 1 (not to be confused with S/2016 J 1, discussed on this list a few days ago); _and_ a recovery of another Jovian
    Message 1 of 8 , Jun 5, 2017
      Hello all,

      We have a "new guy", S/2017 J 1 (not to be confused
      with S/2016 J 1, discussed on this list a few days ago);
      _and_ a recovery of another Jovian from fourteen years ago,
      S/2003 J 15 :

      http://www.minorplanetcenter.net/mpec/K17/K17L47.html
      http://www.minorplanetcenter.net/mpec/K17/K17L46.html

      I've updated my solution for the latter and added one for
      the former on my natural satellites page,

      https://www.projectpluto.com/natsats/summary.htm

      -- Bill
    • Brian Skiff
      On Mon, 2017-06-05 at 14:44 -0400, Bill Gray pluto@projectpluto.com ... It wasn t obvious from the MPEC that 2017 J1 is new, since the astrometry table is
      Message 2 of 8 , Jun 5, 2017
        On Mon, 2017-06-05 at 14:44 -0400, Bill Gray pluto@...
        [mpml] wrote:
        > Hello all,
        >
        > We have a "new guy", S/2017 J 1 (not to be confused
        > with S/2016 J 1, discussed on this list a few days ago);
        > _and_ a recovery of another Jovian from fourteen years ago,
        > S/2003 J 15 :
        >
        > http://www.minorplanetcenter.net/mpec/K17/K17L47.html
        > http://www.minorplanetcenter.net/mpec/K17/K17L46.html


        It wasn't obvious from the MPEC that 2017 J1 is new,
        since the astrometry table is headed "additional observations",
        implying that there already are some. But then the
        residuals table shows only the dates at the top.


        \Brian
      • Patrick Schmeer
        Hello, Bill and Brian, I wonder what s the discovery date? 24 February 2017? Patrick ... Brian Skiff bas@lowell.edu [mpml] wrote: On Mon, 2017-06-05 at 14:44
        Message 3 of 8 , Jun 5, 2017
          Hello, Bill and Brian,

          I wonder what's the discovery date?
          24 February 2017?

          Patrick

          --------------------------------------------
          Brian Skiff bas@... [mpml] wrote:

          On Mon, 2017-06-05 at 14:44 -0400,
          Bill Gray pluto@... [mpml] wrote:
          > Hello all,
          >
          > We have a "new guy", S/2017 J 1 (not to be confused
          > with S/2016 J 1, discussed on this list a few days ago);
          > _and_ a recovery of another Jovian from fourteen years ago,
          > S/2003 J 15 :
          >
          > http://www.minorplanetcenter.net/mpec/K17/K17L47.html
          > http://www.minorplanetcenter.net/mpec/K17/K17L46.html

          It wasn't obvious from the MPEC that 2017 J1 is new,
          since the astrometry table is headed "additional observations",
          implying that there already are some. But then the
          residuals table shows only the dates at the top.

          \Brian
        • Brian Skiff
          ... If they are still using the asterisk (*) to signify the discovery observation, then that was missing, too. So it looks as though there was a bookkeeping
          Message 4 of 8 , Jun 5, 2017
            On Mon, 2017-06-05 at 19:00 +0000, Patrick Schmeer wrote:
            > Hello, Bill and Brian,
            >
            > I wonder what's the discovery date?
            > 24 February 2017?

            If they are still using the asterisk (*) to signify
            the discovery observation, then that was missing, too.
            So it looks as though there was a bookkeeping slip
            with this one. Since it has the 2017 designation,
            I guess one assumes the first 2017 observation is "it".


            \Brian
          • Bill Gray
            Hi Brian, Patrick, I dunno how MPC does the bookkeeping for natural satellites. However, if you d handed me the first six observations, covering three
            Message 5 of 8 , Jun 5, 2017
              Hi Brian, Patrick,

              I dunno how MPC does the bookkeeping for natural satellites.
              However, if you'd handed me the first six observations,
              covering three nights, I would have said to you: "These are
              probably observations of a single, new object. But I'm not
              absolutely sure of that; it could be a spurious linkage.
              Here's an orbit based on those three nights; see if maybe you
              got confirming observations on other nights, or use the
              ephems to see if you can find it on your next observing run."

              After the next observing run, on March 23, I'd have
              congratulated you on your discovery.

              In short, I'd not consider it to be "discovered" until you're
              confident, to some desired probability, that all the observations
              are of the same object.

              Truthfully, my ability to quantify that probability isn't
              what I'd like it to be. It is roughly equivalent to the problem:
              "I just got observations consistent with object X; they're in
              the area I'd expect for X, and the motion matches. What's the
              probability that it's actually not X?"

              I expect to solve this by looking through "known objects" and
              finding out how many are in that area with similar motion and
              magnitude. From this, I may say something like, "There ought
              to be about three objects passing through that area matching
              motion to the degree you specify, so you've only got a one in
              four chance that your object is really X." Or I might say, "I'd
              only expect 0.001 objects matching that description, so I'm 99.9%
              confident that yes, you really did get X."

              Note that this is all theory with me thus far, not working and
              tested code. But it seems reasonable...

              Note also that I've some confidence that this will work for
              asteroids, where we know the population statistics pretty well.
              It may not be so successful with irregular gas giant satellites,
              where there are still, as Donald Rumsfeld would say, "unknown
              unknowns, the things we don't know that we don't know."

              -- Bill

              On 2017-06-05 15:08, Brian Skiff bas@... [mpml] wrote:
              > On Mon, 2017-06-05 at 19:00 +0000, Patrick Schmeer wrote:
              >> Hello, Bill and Brian,
              >>
              >> I wonder what's the discovery date?
              >> 24 February 2017?
              >
              > If they are still using the asterisk (*) to signify
              > the discovery observation, then that was missing, too.
              > So it looks as though there was a bookkeeping slip
              > with this one. Since it has the 2017 designation,
              > I guess one assumes the first 2017 observation is "it".
              >
              > \Brian
              >
              > ------------------------------------
              > Posted by: Brian Skiff <bas@...>
              > ------------------------------------
            • Brian Skiff
              ... Since they are keeping the observations in-house until they do their own follow-up, I presume they are doing their own orbit calculation. Chad Trujillo is
              Message 6 of 8 , Jun 5, 2017
                On Mon, 2017-06-05 at 15:28 -0400, Bill Gray wrote:
                > Hi Brian, Patrick,
                >
                > I dunno how MPC does the bookkeeping for natural satellites.
                > However, if you'd handed me the first six observations,
                > covering three nights, I would have said to you: "These are
                > probably observations of a single, new object. But I'm not
                > absolutely sure of that; it could be a spurious linkage.
                > Here's an orbit based on those three nights; see if maybe you
                > got confirming observations on other nights, or use the
                > ephems to see if you can find it on your next observing run."
                >
                > After the next observing run, on March 23, I'd have
                > congratulated you on your discovery.
                >
                > In short, I'd not consider it to be "discovered" until you're
                > confident, to some desired probability, that all the observations
                > are of the same object.

                Since they are keeping the observations in-house
                until they do their own follow-up, I presume they are
                doing their own orbit calculation. Chad Trujillo is now
                at NAU in Flagstaff, and has access to the Lowell 4.3-m
                DCT telescope for follow-up.


                \Brian
              • Bill Gray
                Further comments on these objects at : http://www.skyandtelescope.com/astronomy-news/two-new-satellites-for-jupiter/
                Message 7 of 8 , Jun 6, 2017
                  Further comments on these objects at :

                  http://www.skyandtelescope.com/astronomy-news/two-new-satellites-for-jupiter/
                  http://home.dtm.ciw.edu/users/sheppard/satellites/jup2017.html

                  These discoveries were apparently a byproduct of a search for
                  TNOs and/or "Planet X"; Jupiter was conveniently nearby, so they
                  could arrange for the satellites to be in the same fields as the
                  TNOs. I gather that makes this a Jupiter-only deal; it'll be a
                  long time before any other gas giant is in that part of the sky.

                  There's a comment about possibly linking the two new objects to the
                  2003 objects. I tried that. The one-sigma uncertainties for both
                  of the "new" objects is about a dozen arcseconds when you go back
                  to 2003, so the linkage wouldn't have been a challenge. (Though
                  now that we know about the two new guys, and can get decent positions
                  for them in old images, I'd think some precoveries may be found.)

                  The article also has also a comment about probably having all the
                  lost guys recovered, plus new ones, just awaiting confirmation next
                  year when Jupiter gets in the right neighborhood again. So we may
                  get some new data to play with eventually.

                  -- Bill

                  On 2017-06-05 15:52, Brian Skiff bas@... [mpml] wrote:
                  > On Mon, 2017-06-05 at 15:28 -0400, Bill Gray wrote:
                  >> Hi Brian, Patrick,
                  >>
                  >> I dunno how MPC does the bookkeeping for natural satellites.
                  >> However, if you'd handed me the first six observations,
                  >> covering three nights, I would have said to you: "These are
                  >> probably observations of a single, new object. But I'm not
                  >> absolutely sure of that; it could be a spurious linkage.
                  >> Here's an orbit based on those three nights; see if maybe you
                  >> got confirming observations on other nights, or use the
                  >> ephems to see if you can find it on your next observing run."
                  >>
                  >> After the next observing run, on March 23, I'd have
                  >> congratulated you on your discovery.
                  >>
                  >> In short, I'd not consider it to be "discovered" until you're
                  >> confident, to some desired probability, that all the observations
                  >> are of the same object.
                  >
                  > Since they are keeping the observations in-house
                  > until they do their own follow-up, I presume they are
                  > doing their own orbit calculation. Chad Trujillo is now
                  > at NAU in Flagstaff, and has access to the Lowell 4.3-m
                  > DCT telescope for follow-up.
                  >
                  >
                  > \Brian
                  >
                  >
                  >
                  >
                  > ------------------------------------
                  > Posted by: Brian Skiff <bas@...>
                  > ------------------------------------
                  >
                  > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                  >
                  > Posts to this list or information found within may be freely used, with the stipulation that MPML and the originating author are cited as the source of the information.
                  > ------------------------------------
                  >
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                  >
                  >
                  >
                • Patrick Schmeer
                  NUMBERING OF NATURAL SATELLITES (M.P.C. 105280) S/2017 J 1 = Jupiter LIX S/2016 J 1 = Jupiter LIV S/2003 J 15 = Jupiter LVIII Also: S/2011 J 2 = Jupiter LVI
                  Message 8 of 8 , Jun 12, 2017
                    "NUMBERING OF NATURAL SATELLITES"
                    (M.P.C. 105280)

                    S/2017 J 1 = Jupiter LIX
                    S/2016 J 1 = Jupiter LIV
                    S/2003 J 15 = Jupiter LVIII

                    Also:
                    S/2011 J 2 = Jupiter LVI
                    S/2003 J 18 = Jupiter LV
                    S/2003 J 5 = Jupiter LVII

                    Regards,
                    Patrick
                    --------------------------------------------
                    "Bill Gray" <pluto@...> [mpml] wrote:

                    Subject: {MPML} Another new Jovian satellite, and another recovery
                    To: "MPML" <mpml@yahoogroups.com>
                    Date: 5 June 2017

                    Hello all,

                    We have a "new guy", S/2017 J 1 (not to
                    be confused with S/2016 J 1, discussed
                    on this list a few days ago);
                    _and_ a recovery of another Jovian from
                    fourteen years ago, S/2003 J 15 :

                    http://www.minorplanetcenter.net/mpec/K17/K17L47.html
                    http://www.minorplanetcenter.net/mpec/K17/K17L46.html

                    I've updated my solution for the latter and
                    added one for the former on my natural
                    satellites page,

                    https://www.projectpluto.com/natsats/summary.htm

                    -- Bill
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