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2012 DA14 recovered

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  • Bill Gray
    Tucked into the Daily Orbit Update for today, one can find: K12D14A C2013 01 09.04356 23 32 36.395-67 13 54.16 23.4 rcEA051304 K12D14A C2013 01
    Message 1 of 8 , Jan 10, 2013
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      Tucked into the Daily Orbit Update for today, one can find:


      K12D14A C2013 01 09.04356 23 32 36.395-67 13 54.16 23.4 rcEA051304
      K12D14A C2013 01 09.04853 23 32 37.021-67 13 55.01 23.5 rcEA051304
      K12D14A C2013 01 09.05349 23 32 37.640-67 13 56.00 23.4 rcEA051304

      ...three positions from (304) Las Campanas Observatory. With these, the
      uncertainty for the upcoming flyby obviously drops a lot:

      Orbital elements: 2012 DA14
      Perigee 2013 Feb 15.809618 +/- 3.47e-5 TT = 19:25:51 (JD 2456339.309618)
      Epoch 2013 Feb 15.8 TT = JDT 2456339.3 Find_Orb
      q 34106.4818 +/- 226
      H 24.4 G 0.15 Peri. 354.07337 +/- 4.7
      Node 175.06341 +/- 26
      e 4.2293573 +/- 0.0213 Incl. 86.21304 +/- 9
      191 of 194 observations 2012 Feb. 23-2013 Jan. 9; mean residual 0".373.

      (before, I got q = 37810 +/- 9000 km.)

      -- Bill
    • Gerald McKeegan
      It looks like these new observations put the nominal closest approach distance on 15 February about 800 km closer to Earth. Gerald
      Message 2 of 8 , Jan 10, 2013
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        It looks like these new observations put the nominal closest approach distance on 15 February about 800 km closer to Earth.

        Gerald


        -----Original Message-----
        >From: Bill Gray <pluto@...>
        >Sent: Jan 10, 2013 10:18 AM
        >To: MPML <mpml@yahoogroups.com>
        >Subject: {MPML} 2012 DA14 recovered
        >
        > Tucked into the Daily Orbit Update for today, one can find:
        >
        >
        > K12D14A C2013 01 09.04356 23 32 36.395-67 13 54.16 23.4 rcEA051304
        > K12D14A C2013 01 09.04853 23 32 37.021-67 13 55.01 23.5 rcEA051304
        > K12D14A C2013 01 09.05349 23 32 37.640-67 13 56.00 23.4 rcEA051304
        >
        > ...three positions from (304) Las Campanas Observatory. With these, the
        >uncertainty for the upcoming flyby obviously drops a lot:
        >
        >Orbital elements: 2012 DA14
        > Perigee 2013 Feb 15.809618 +/- 3.47e-5 TT = 19:25:51 (JD 2456339.309618)
        >Epoch 2013 Feb 15.8 TT = JDT 2456339.3 Find_Orb
        >q 34106.4818 +/- 226
        >H 24.4 G 0.15 Peri. 354.07337 +/- 4.7
        > Node 175.06341 +/- 26
        >e 4.2293573 +/- 0.0213 Incl. 86.21304 +/- 9
        >191 of 194 observations 2012 Feb. 23-2013 Jan. 9; mean residual 0".373.
        >
        > (before, I got q = 37810 +/- 9000 km.)
        >
        >-- Bill
        >
        >
        >------------------------------------
        >
        >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        >
        >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! Groups Links
        >
        >
        >
      • Bill Gray
        Hi Gerald, I d have said it was nudged in by more like 3700 km (per my previous message: before, q was 37810 +/- 9000 km; now, I m getting 34106 +/- 226
        Message 3 of 8 , Jan 10, 2013
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          Hi Gerald,

          I'd have said it was nudged in by more like 3700 km (per my previous
          message: before, q was 37810 +/- 9000 km; now, I'm getting 34106
          +/- 226 km.) Much depends on the weighting of observations, though.

          Pseudo-MPEC is at

          http://www.projectpluto.com/temp/da14.htm

          The recovery was about an arcminute off prediction. The predicted mag was
          about 24.2, though it was observed to be around 23.4. Maybe it was caught
          at a bright part of the light curve. That might also explain why, though
          the (304) data has residuals of a bit over an arcsecond, they're all within
          .1 arcsecond of the predicted track.

          -- Bill
        • wlodarczyk_i
          Using the OrbFit software and 194 observations of asteroid 2012 DA14 I have computed: Close approach to EARTH on 2013/02/15.80959 at 0.00022802 AU (about 34112
          Message 4 of 8 , Jan 10, 2013
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            Using the OrbFit software and 194 observations of asteroid 2012 DA14
            I have computed:
            Close approach to EARTH on 2013/02/15.80959 at 0.00022802 AU (about 34112 km),
            Best regards,
            Ireneusz Wlodarczyk
            553 Chorzow


            --- In mpml@yahoogroups.com, Bill Gray wrote:
            >
            > Hi Gerald,
            >
            > I'd have said it was nudged in by more like 3700 km (per my previous
            > message: before, q was 37810 +/- 9000 km; now, I'm getting 34106
            > +/- 226 km.) Much depends on the weighting of observations, though.
            >
            > Pseudo-MPEC is at
            >
            > http://www.projectpluto.com/temp/da14.htm
            >
            > The recovery was about an arcminute off prediction. The predicted mag was
            > about 24.2, though it was observed to be around 23.4. Maybe it was caught
            > at a bright part of the light curve. That might also explain why, though
            > the (304) data has residuals of a bit over an arcsecond, they're all within
            > .1 arcsecond of the predicted track.
            >
            > -- Bill
            >
          • Gerald McKeegan
            Hi Bill, I was going off the JPL numbers. Two days ago, they were giving a close approach distance of 0.0002337995 AU (34,976 km), based on the observations
            Message 5 of 8 , Jan 10, 2013
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              Hi Bill,

              I was going off the JPL numbers. Two days ago, they were giving a close approach distance of 0.0002337995 AU (34,976 km), based on the observations through May. With the new data, JPL now shows a nominal close approach of 0.000228014368 AU (34,110 km). That's were I got the 800 km difference I mentioned in my earlier email (actually about 866 km). It looks like their new value for q is pretty close to yours.

              Gerald


              -----Original Message-----
              >From: Bill Gray <pluto@...>
              >Sent: Jan 10, 2013 10:50 AM
              >To: Gerald McKeegan <geraldspace@...>
              >Cc: MPML <mpml@yahoogroups.com>
              >Subject: Re: {MPML} 2012 DA14 recovered
              >
              >Hi Gerald,
              >
              > I'd have said it was nudged in by more like 3700 km (per my previous
              >message: before, q was 37810 +/- 9000 km; now, I'm getting 34106
              >+/- 226 km.) Much depends on the weighting of observations, though.
              >
              > Pseudo-MPEC is at
              >
              >http://www.projectpluto.com/temp/da14.htm
              >
              > The recovery was about an arcminute off prediction. The predicted mag was
              >about 24.2, though it was observed to be around 23.4. Maybe it was caught
              >at a bright part of the light curve. That might also explain why, though
              >the (304) data has residuals of a bit over an arcsecond, they're all within
              >.1 arcsecond of the predicted track.
              >
              >-- Bill
              >
              >
              >------------------------------------
              >
              >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
              >
              >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! Groups Links
              >
              >
              >
            • dfischer@astro.uni-bonn.de
              ... Only 350 km or so: when I ran JPL Horizons last August, the closest approach to the Earth s center was 34,975 km, now it is 34,610 km. Back at the time
              Message 6 of 8 , Jan 10, 2013
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                > It looks like these new observations put the nominal closest approach
                > distance on 15 February about 800 km closer to Earth.

                Only 350 km or so: when I ran JPL Horizons last August, the closest
                approach to the Earth's center was 34,975 km, now it is 34,610 km. Back at
                the time someone - at JPL? - advised me that the uncertainty of the C/A
                distance was still in the 1000s of kilometers, seemingly quite an
                underestimate. Do we have a good handle on the precision of the orbit
                *now*? I'm just wondering when one could start plotting the track of 2012
                DA14 into sky maps (for specific locations) to guide visual observers;
                after all it will peak around 7.5 mag. And the visibility in Europe - with
                the asteroid rising just minutes after C/A - will be excellent; in
                http://bonnstern.wordpress.com/2013/01/10/wenn-asteroid-2012-da14-zu-besuch-kommt-neue-zahlen
                I just tabulated the data for every 10° of elevation gained as seen from
                Cologne.

                Daniel
              • Bill Gray
                ... Again: it depends on which estimate you re looking at. JPL, MPC, and I are all using different weighting schemes. We were all within each other s
                Message 7 of 8 , Jan 10, 2013
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                  On 01/10/2013 05:34 PM, dfischer@...-bonn.de wrote:
                  >> It looks like these new observations put the nominal closest approach
                  >> distance on 15 February about 800 km closer to Earth.
                  >
                  > Only 350 km or so: when I ran JPL Horizons last August, the closest
                  > approach to the Earth's center was 34,975 km, now it is 34,610 km.

                  Again: it depends on which estimate you're looking at. JPL, MPC,
                  and I are all using different weighting schemes. We were all within
                  each other's sigmas, and I'm pretty sure we'll be within each other's
                  new sigmas. But those sigmas will be a lot smaller now (in my case,
                  about 40 times smaller).

                  > Back at
                  > the time someone - at JPL? - advised me that the uncertainty of the C/A
                  > distance was still in the 1000s of kilometers, seemingly quite an
                  > underestimate.

                  I had an uncertainty of 9000 km. I vaguely recall JPL's sigma being
                  in that neighborhood.

                  > Do we have a good handle on the precision of the orbit
                  > *now*? I'm just wondering when one could start plotting the track of 2012
                  > DA14 into sky maps (for specific locations) to guide visual observers;
                  > after all it will peak around 7.5 mag.

                  The ephemeris uncertainty near perigee looks to be about a quarter of
                  a degree. Good enough to do planning, anyway.

                  -- Bill
                • Paul Chodas
                  Horizons is currently reporting a close approach distance of 0.000228 au = 34,108 km, not 34,610 km. The current position uncertainty at close approach is on
                  Message 8 of 8 , Jan 10, 2013
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                    Horizons is currently reporting a close approach distance of 0.000228 au
                    = 34,108 km, not 34,610 km. The current position uncertainty at close
                    approach is on the order of 100 km or so, much smaller than ~8000 km,
                    which was the uncertainty before the new data from Las Campanas. Just
                    because the nominal didn't change much doesn't mean the old uncertainty
                    estimate was an overestimate.

                    Paul Chodas

                    On 1/10/2013 2:34 PM, dfischer@...-bonn.de wrote:
                    >> It looks like these new observations put the nominal closest approach
                    >> distance on 15 February about 800 km closer to Earth.
                    > Only 350 km or so: when I ran JPL Horizons last August, the closest
                    > approach to the Earth's center was 34,975 km, now it is 34,610 km. Back at
                    > the time someone - at JPL? - advised me that the uncertainty of the C/A
                    > distance was still in the 1000s of kilometers, seemingly quite an
                    > underestimate. Do we have a good handle on the precision of the orbit
                    > *now*? I'm just wondering when one could start plotting the track of 2012
                    > DA14 into sky maps (for specific locations) to guide visual observers;
                    > after all it will peak around 7.5 mag. And the visibility in Europe - with
                    > the asteroid rising just minutes after C/A - will be excellent; in
                    > http://bonnstern.wordpress.com/2013/01/10/wenn-asteroid-2012-da14-zu-besuch-kommt-neue-zahlen
                    > I just tabulated the data for every 10° of elevation gained as seen from
                    > Cologne.
                    >
                    > Daniel
                    >
                    >
                    >
                    > ------------------------------------
                    >
                    > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                    >
                    > 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! Groups Links
                    >
                    >
                    >

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