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MPEC J04: 2009 HC82 [a=2.26,e=0.82,i=154.6,H=16.2,PHA] [26220-2011/02-R1]

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  • Jean-Claude MERLIN
    Hi all, 2009 HC82 is apparently the first known Apollo object with a retrograde orbit. Quite a big rock (2-3 km). There was already an Amor type object in that
    Message 1 of 4 , May 1, 2009
      Hi all,

      2009 HC82 is apparently the first known Apollo object with a retrograde orbit.
      Quite a big rock (2-3 km).
      There was already an Amor type object in that case : 2007 VA85

      JCM


      ----- Original Message -----
      From: "MPEC mailing list" <qmpc@...>
      To: <JCMerlin@...>
      Sent: Friday, May 01, 2009 6:58 PM
      Subject: MPEC J04: 2009 HC82 [a=2.26,e=0.82,i=154.6,H=16.2,PHA] [26220-2011/02-R1]


      >
      > M.P.E.C. 2009-J04 Issued 2009 May 1, 16:39 UT
      >
      > 2009 HC82
      >
      > Orbital elements:
      > 2009 HC82 PHA, Earth MOID = 0.0235 AU
      > Epoch 2009 June 18.0 TT = JDT 2455000.5 MPC
      > M 64.79849 (2000.0) P Q
      > n 0.29099311 Peri. 291.70705 +0.91746366 +0.06497679
      > a 2.2553516 Node 293.55963 +0.15508685 -0.96693369
      > e 0.8222477 Incl. 154.64869 -0.36634479 -0.24661155
      > P 3.39 H 16.2 G 0.15 U 9
      > q = 0.4009
    • Brian Skiff
      ... Name a e i q 1999 XS35 17.9 0.95 19.4 0.95 2005 VD 6.67 0.25 172.8 0.30 2007 VA85 3.9 0.72 132.6 1.09
      Message 2 of 4 , May 1, 2009
        On Fri, 2009-05-01 at 19:56 +0200, Jean-Claude MERLIN wrote:
        > Hi all,
        >
        > 2009 HC82 is apparently the first known Apollo object with a retrograde orbit.
        > Quite a big rock (2-3 km).
        > There was already an Amor type object in that case : 2007 VA85
        >
        > JCM
        >


        Name a e i q
        1999 XS35 17.9 0.95 19.4 0.95
        2005 VD 6.67 0.25 172.8 0.30
        2007 VA85 3.9 0.72 132.6 1.09
        2009 HC82 2.25 0.82 154.6 0.40


        The first two objects have much larger orbits but are nevertheless
        Earth-crossers (one prograde, one retrograde). It's not obvious
        to me that they're so different (ex-comets or ex-Oort-cloud asteroids).
        Am I missing something here?


        \Brian
      • Bill J Gray
        Hi Jean-Claude, This may yet turn out to be something more comet-like. The orbit below (and some intermediate ones) fit reasonably well. Further observations
        Message 3 of 4 , May 1, 2009
          Hi Jean-Claude,

          This may yet turn out to be something more comet-like. The
          orbit below (and some intermediate ones) fit reasonably well.
          Further observations may be desirable. (Though there's no
          rush; the positional uncertainty isn't going to grow by much
          in the next few days. Conversely, getting more data right
          away won't firm up the orbit tremendously.)

          -- Bill

          2009 HC82
          Perihelion 2008 Oct 31.957548 TT; Constraint: e=1
          Epoch 2009 May 1.0 TT = JDT 2454952.5 Earth MOID: 0.3165 Ma: 0.0661
          q 1.33146335 (2000.0) P Q
          H 15.6 G 0.15 Peri. 356.40906 0.57485821 -0.72431766
          Node 301.89495 -0.73912005 -0.65924159
          e 1.0 Incl. 153.36193 -0.35105493 0.20190207
          From 18 observations 2009 Apr. 29-May 1; RMS error 0.951 arcseconds

          Residuals in arcseconds:
          090429 703( 1.4- 2.6-) 090429 703 .34- .90+ 090501 854 .64+ .31-
          090429 703 .59- 1.1- 090430 G96 .63+ .88+ 090501 854 .09+ 1.5-
          090429 703 .07- 1.2- 090430 G96 .58+ .58+ 090501 854( 2.3- 3.7-)
          090429 703 .74+ .69- 090430 G96 .54+ .93+ 090501 291 .46- .40-
          090429 703 .06- .20+ 090430 G96 .11+ 1.1+ 090501 291 .33- .52-
          090429 703 .82+ .18- 090430 A13 .36- .72+ 090501 291 .29- .40-
          090429 703 .96- .21+ 090430 A13 .28- 1.0+
        • Jean-Claude MERLIN
          Hi Bill and Brian, OK, thanks. Probably extinct comet nuclei effectively. I didn t know that the retrograde inclination was a criterion for the Damocloid
          Message 4 of 4 , May 2, 2009
            Hi Bill and Brian,

            OK, thanks.
            Probably "extinct" comet nuclei effectively.
            I didn't know that the retrograde inclination was a criterion for the Damocloid population.

            JC


            ----- Original Message -----
            From: Bill J Gray
            To: MPML
            Sent: Saturday, May 02, 2009 2:52 AM
            Subject: Re: {MPML} MPEC J04: 2009 HC82 [a=2.26,e=0.82,i=154.6,H=16.2,PHA] [26220-2011/02-R1]





            Hi Jean-Claude,

            This may yet turn out to be something more comet-like. The
            orbit below (and some intermediate ones) fit reasonably well.
            Further observations may be desirable. (Though there's no
            rush; the positional uncertainty isn't going to grow by much
            in the next few days. Conversely, getting more data right
            away won't firm up the orbit tremendously.)

            -- Bill

            2009 HC82
            Perihelion 2008 Oct 31.957548 TT; Constraint: e=1
            Epoch 2009 May 1.0 TT = JDT 2454952.5 Earth MOID: 0.3165 Ma: 0.0661
            q 1.33146335 (2000.0) P Q
            H 15.6 G 0.15 Peri. 356.40906 0.57485821 -0.72431766
            Node 301.89495 -0.73912005 -0.65924159
            e 1.0 Incl. 153.36193 -0.35105493 0.20190207
            From 18 observations 2009 Apr. 29-May 1; RMS error 0.951 arcseconds

            Residuals in arcseconds:
            090429 703( 1.4- 2.6-) 090429 703 .34- .90+ 090501 854 .64+ .31-
            090429 703 .59- 1.1- 090430 G96 .63+ .88+ 090501 854 .09+ 1.5-
            090429 703 .07- 1.2- 090430 G96 .58+ .58+ 090501 854( 2.3- 3.7-)
            090429 703 .74+ .69- 090430 G96 .54+ .93+ 090501 291 .46- .40-
            090429 703 .06- .20+ 090430 G96 .11+ 1.1+ 090501 291 .33- .52-
            090429 703 .82+ .18- 090430 A13 .36- .72+ 090501 291 .29- .40-
            090429 703 .96- .21+ 090430 A13 .28- 1.0+




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