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2011 MD = _not_ space junk: new elements

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  • Bill J Gray
    Hello all, I got a request to post new elements on-list. If you use the first set of elements below (epoch 26 June) to compute positions for 27 June, you ll
    Message 1 of 5 , Jun 25 6:50 AM
      Hello all,

      I got a request to post new elements on-list. If you use the first set
      of elements below (epoch 26 June) to compute positions for 27 June, you'll
      be off by about a quarter of a degree. So use the first set until 26.5
      June or so, the second set after that.

      Properly speaking, we should be using geocentric elements, what with
      this object being within the earth's sphere of influence (about 920000 km).
      But most software won't handle those... just for yuks, though, I've
      added them at the bottom of this message.

      The perturbations are really pretty strong at this point, of course.
      But they're mostly in the direction toward us... because, of course,
      that's the direction in which the earth is pulling this thing. Which is
      why you can still get decent RA/dec values with these elements; almost
      all the error will be radial.

      Adding last night's DOU decreased the sigmas about fourfold. However,
      bumping the epoch up a couple of days doubled the sigmas, which are
      higher when one is near a planetary encounter or further outside the
      observation arc. And you can also see that the U parameter goes up from
      4.6 for one epoch, to 5.1 for the next day's epoch. Which is one reason
      one shouldn't rely on the U parameter to mean much of anything.

      Anyway. The extra data also turns the "maybe it's an encounter" 1962
      pass into a very clean miss at .064 AU. So this object is a for-real
      rock. (I don't see Tabare Gallardo's 1978 encounter at all... dunno
      what's going on there.)

      -- Bill

      Orbital elements:
      2011 MD
      Perihelion 2011 Aug 19.615850 TT = 14:46:49 (JD 2455793.115850)
      Epoch 2011 Jun 26.0 TT = JDT 2455738.5 Earth MOID: 0.0002
      M 308.981769 (2000.0) P Q
      n 0.934128655 Peri. 231.789816 0.842745464 0.534660243
      a 1.036409979 Node 95.806600 -0.472138395 0.789992521
      e 0.02968618 Incl. 3.607480 -0.258583481 0.300083722
      P 1.06/385.38d H 28.3 U 4.6 q 1.005642920 Q 1.067177039
      From 122 observations 2011 June 22-25; mean residual 0".445.

      Orbital elements:
      2011 MD
      Perihelion 2011 Aug 10.325120 TT = 7:48:10 (JD 2455783.825120)
      Epoch 2011 Jun 27.0 TT = JDT 2455739.5 Earth MOID: 0.0002
      M 319.510282 (2000.0) P Q
      n 0.913471135 Peri. 223.208871 0.750511790 0.656650808
      a 1.051976803 Node 95.591627 -0.584130302 0.711836000
      e 0.04466404 Incl. 4.289671 -0.309069316 0.249197159
      P 1.08/394.09d H 28.3 U 5.1 q 1.004991263 Q 1.098962343
      From 122 observations 2011 June 22-25; mean residual 0".445.

      Sigmas (for 27 June elements):
      sigma_Tp 0.00336 days
      sigma_e 8.21e-6
      sigma_q 6.62e-7 AU (99.1 km)
      sigma_Q 1.74e-5 AU (2603 km)
      sigma_1/a 7.58e-6 1/AU
      sigma_i 0.000393 deg
      sigma_M 0.00355 deg
      sigma_omega 0.00289 deg
      sigma_Omega 0.000245 deg
      sigma_n: 1.09e-5
      sigma_a: 8.39e-6 AU (1255 km)
      sigma_P: 0.00472 days

      Orbital elements (geocentric):
      2011 MD
      Perigee 2011 Jun 27.708875 TT = 17:00:46 (JD 2455740.208875)
      Epoch 2011 Jun 27.0 TT = JDT 2455739.5 Find_Orb
      q 18627.9 +/- 5 km (2000.0) P Q
      H 28.3 G 0.15 Peri. 281.756305 -0.188192857 -0.781210704
      Node 43.407969 0.791883657 -0.479189217
      e 1.10208155 Incl. 119.982878 -0.580950704 -0.400109395
    • P. Clay Sherrod
      Thanks very much for these updates, Bill....very useful and much appreciated. Clay _____ Dr. P. Clay Sherrod Arkansas Sky Observatories MPC H45 - Petit Jean
      Message 2 of 5 , Jun 25 7:26 AM
        Thanks very much for these updates, Bill....very useful and much appreciated.

        Clay
        _____
        Dr. P. Clay Sherrod
        Arkansas Sky Observatories
        MPC H45 - Petit Jean Mountain South
        MPC H41 - Petit Jean Mountain
        MPC H43 - Conway West
        http://www.arksky.org/

        ----- Original Message -----
        From: "Bill J Gray" <pluto@...>
        To: "MPML" <mpml@yahoogroups.com>
        Sent: Saturday, June 25, 2011 8:50 AM
        Subject: {MPML} 2011 MD = _not_ space junk: new elements


        > Hello all,
        >
        > I got a request to post new elements on-list. If you use the first set
        > of elements below (epoch 26 June) to compute positions for 27 June, you'll
        > be off by about a quarter of a degree. So use the first set until 26.5
        > June or so, the second set after that.
        >
        > Properly speaking, we should be using geocentric elements, what with
        > this object being within the earth's sphere of influence (about 920000 km).
        > But most software won't handle those... just for yuks, though, I've
        > added them at the bottom of this message.
        >
        > The perturbations are really pretty strong at this point, of course.
        > But they're mostly in the direction toward us... because, of course,
        > that's the direction in which the earth is pulling this thing. Which is
        > why you can still get decent RA/dec values with these elements; almost
        > all the error will be radial.
        >
        > Adding last night's DOU decreased the sigmas about fourfold. However,
        > bumping the epoch up a couple of days doubled the sigmas, which are
        > higher when one is near a planetary encounter or further outside the
        > observation arc. And you can also see that the U parameter goes up from
        > 4.6 for one epoch, to 5.1 for the next day's epoch. Which is one reason
        > one shouldn't rely on the U parameter to mean much of anything.
        >
        > Anyway. The extra data also turns the "maybe it's an encounter" 1962
        > pass into a very clean miss at .064 AU. So this object is a for-real
        > rock. (I don't see Tabare Gallardo's 1978 encounter at all... dunno
        > what's going on there.)
        >
        > -- Bill
        >
        > Orbital elements:
        > 2011 MD
        > Perihelion 2011 Aug 19.615850 TT = 14:46:49 (JD 2455793.115850)
        > Epoch 2011 Jun 26.0 TT = JDT 2455738.5 Earth MOID: 0.0002
        > M 308.981769 (2000.0) P Q
        > n 0.934128655 Peri. 231.789816 0.842745464 0.534660243
        > a 1.036409979 Node 95.806600 -0.472138395 0.789992521
        > e 0.02968618 Incl. 3.607480 -0.258583481 0.300083722
        > P 1.06/385.38d H 28.3 U 4.6 q 1.005642920 Q 1.067177039
        > From 122 observations 2011 June 22-25; mean residual 0".445.
        >
        > Orbital elements:
        > 2011 MD
        > Perihelion 2011 Aug 10.325120 TT = 7:48:10 (JD 2455783.825120)
        > Epoch 2011 Jun 27.0 TT = JDT 2455739.5 Earth MOID: 0.0002
        > M 319.510282 (2000.0) P Q
        > n 0.913471135 Peri. 223.208871 0.750511790 0.656650808
        > a 1.051976803 Node 95.591627 -0.584130302 0.711836000
        > e 0.04466404 Incl. 4.289671 -0.309069316 0.249197159
        > P 1.08/394.09d H 28.3 U 5.1 q 1.004991263 Q 1.098962343
        > From 122 observations 2011 June 22-25; mean residual 0".445.
        >
        > Sigmas (for 27 June elements):
        > sigma_Tp 0.00336 days
        > sigma_e 8.21e-6
        > sigma_q 6.62e-7 AU (99.1 km)
        > sigma_Q 1.74e-5 AU (2603 km)
        > sigma_1/a 7.58e-6 1/AU
        > sigma_i 0.000393 deg
        > sigma_M 0.00355 deg
        > sigma_omega 0.00289 deg
        > sigma_Omega 0.000245 deg
        > sigma_n: 1.09e-5
        > sigma_a: 8.39e-6 AU (1255 km)
        > sigma_P: 0.00472 days
        >
        > Orbital elements (geocentric):
        > 2011 MD
        > Perigee 2011 Jun 27.708875 TT = 17:00:46 (JD 2455740.208875)
        > Epoch 2011 Jun 27.0 TT = JDT 2455739.5 Find_Orb
        > q 18627.9 +/- 5 km (2000.0) P Q
        > H 28.3 G 0.15 Peri. 281.756305 -0.188192857 -0.781210704
        > Node 43.407969 0.791883657 -0.479189217
        > e 1.10208155 Incl. 119.982878 -0.580950704 -0.400109395
        >
        >
        > ------------------------------------
        >
        > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        >
        > 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.Yahoo!
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        >
        >
        >
        >
      • wlodarczyk_i
        Using the OrbFit v.4.2 software I have got minimum distance between the Earth and asteroid 2011 MD, about 0.023 AU at 1962/06/30.1, similar to Bill, Best
        Message 3 of 5 , Jun 25 10:57 AM
          Using the OrbFit v.4.2 software I have got minimum distance between the Earth and asteroid 2011 MD, about 0.023 AU at 1962/06/30.1, similar to Bill,
          Best regards,
          Ireneusz

          --- In mpml@yahoogroups.com, Bill J Gray <pluto@...> wrote:
          >
          > Hello all,
          >
          > I got a request to post new elements on-list. If you use the first set
          > of elements below (epoch 26 June) to compute positions for 27 June, you'll
          > be off by about a quarter of a degree. So use the first set until 26.5
          > June or so, the second set after that.
          >
          > Properly speaking, we should be using geocentric elements, what with
          > this object being within the earth's sphere of influence (about 920000 km).
          > But most software won't handle those... just for yuks, though, I've
          > added them at the bottom of this message.
          >
          > The perturbations are really pretty strong at this point, of course.
          > But they're mostly in the direction toward us... because, of course,
          > that's the direction in which the earth is pulling this thing. Which is
          > why you can still get decent RA/dec values with these elements; almost
          > all the error will be radial.
          >
          > Adding last night's DOU decreased the sigmas about fourfold. However,
          > bumping the epoch up a couple of days doubled the sigmas, which are
          > higher when one is near a planetary encounter or further outside the
          > observation arc. And you can also see that the U parameter goes up from
          > 4.6 for one epoch, to 5.1 for the next day's epoch. Which is one reason
          > one shouldn't rely on the U parameter to mean much of anything.
          >
          > Anyway. The extra data also turns the "maybe it's an encounter" 1962
          > pass into a very clean miss at .064 AU. So this object is a for-real
          > rock. (I don't see Tabare Gallardo's 1978 encounter at all... dunno
          > what's going on there.)
          >
          > -- Bill
          >
          > Orbital elements:
          > 2011 MD
          > Perihelion 2011 Aug 19.615850 TT = 14:46:49 (JD 2455793.115850)
          > Epoch 2011 Jun 26.0 TT = JDT 2455738.5 Earth MOID: 0.0002
          > M 308.981769 (2000.0) P Q
          > n 0.934128655 Peri. 231.789816 0.842745464 0.534660243
          > a 1.036409979 Node 95.806600 -0.472138395 0.789992521
          > e 0.02968618 Incl. 3.607480 -0.258583481 0.300083722
          > P 1.06/385.38d H 28.3 U 4.6 q 1.005642920 Q 1.067177039
          > From 122 observations 2011 June 22-25; mean residual 0".445.
          >
          > Orbital elements:
          > 2011 MD
          > Perihelion 2011 Aug 10.325120 TT = 7:48:10 (JD 2455783.825120)
          > Epoch 2011 Jun 27.0 TT = JDT 2455739.5 Earth MOID: 0.0002
          > M 319.510282 (2000.0) P Q
          > n 0.913471135 Peri. 223.208871 0.750511790 0.656650808
          > a 1.051976803 Node 95.591627 -0.584130302 0.711836000
          > e 0.04466404 Incl. 4.289671 -0.309069316 0.249197159
          > P 1.08/394.09d H 28.3 U 5.1 q 1.004991263 Q 1.098962343
          > From 122 observations 2011 June 22-25; mean residual 0".445.
          >
          > Sigmas (for 27 June elements):
          > sigma_Tp 0.00336 days
          > sigma_e 8.21e-6
          > sigma_q 6.62e-7 AU (99.1 km)
          > sigma_Q 1.74e-5 AU (2603 km)
          > sigma_1/a 7.58e-6 1/AU
          > sigma_i 0.000393 deg
          > sigma_M 0.00355 deg
          > sigma_omega 0.00289 deg
          > sigma_Omega 0.000245 deg
          > sigma_n: 1.09e-5
          > sigma_a: 8.39e-6 AU (1255 km)
          > sigma_P: 0.00472 days
          >
          > Orbital elements (geocentric):
          > 2011 MD
          > Perigee 2011 Jun 27.708875 TT = 17:00:46 (JD 2455740.208875)
          > Epoch 2011 Jun 27.0 TT = JDT 2455739.5 Find_Orb
          > q 18627.9 +/- 5 km (2000.0) P Q
          > H 28.3 G 0.15 Peri. 281.756305 -0.188192857 -0.781210704
          > Node 43.407969 0.791883657 -0.479189217
          > e 1.10208155 Incl. 119.982878 -0.580950704 -0.400109395
          >
        • Gareth
          ... Qualification: for this object. Gareth
          Message 4 of 5 , Jun 25 1:08 PM
            --- In mpml@yahoogroups.com, Bill J Gray <pluto@...> wrote:
            >
            > observation arc. And you can also see that the U parameter goes up from
            > 4.6 for one epoch, to 5.1 for the next day's epoch. Which is one reason
            > one shouldn't rely on the U parameter to mean much of anything.

            Qualification: "for this object."

            Gareth
          • Bill J Gray
            ... True. I should probably say, don t rely on U for much if the object comes near planets. At least as far as I ve noticed, U doesn t have a lot of
            Message 5 of 5 , Jun 25 2:41 PM
              Gareth wrote:
              >
              > --- In mpml@yahoogroups.com <mailto:mpml%40yahoogroups.com>, Bill J Gray
              > <pluto@...> wrote:
              > >
              > > observation arc. And you can also see that the U parameter goes up from
              > > 4.6 for one epoch, to 5.1 for the next day's epoch. Which is one reason
              > > one shouldn't rely on the U parameter to mean much of anything.
              >
              > Qualification: "for this object."

              True. I should probably say, "don't rely on U for much if the object
              comes near planets." At least as far as I've noticed, U doesn't have a
              lot of epoch dependence as long as the object stays away from planets.

              And even with encounters, one can say things such as: "With the
              current data, 2011 MD has U=4.6 for times well before the encounter,
              and U=5.8 for times well after the encounter." I.e., U is reasonably
              stable as long as no perturber messes things up.

              -- Bill
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