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Discovery of 6Q0B44E

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  • Richard Kowalski
    There have been a few questions about this object since people became more aware of it earlier today, so I ll take address what I know so far. Steve Larson,
    Message 1 of 4 , Aug 29, 2006
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      There have been a few questions about this object since people became
      more aware of it earlier today, so I'll take address what I know so far.

      Steve Larson, Rik Hill and I took the opportunity of a break in the
      monsoons to finish aligning the optics on our Schmidt after we cleaned
      the optics earlier this summer. After everything was satisfactory, I
      settled in for a few nights of surveying. During the course of the night
      our software picked out B44E at 19.5 magnitude moving about 4.5 degrees
      a day. As is typical, I sent in my obs to MPC and I also sent them down
      to Rob McNaught at our sister survey at Siding Springs so he could
      provide some follow up. Later I attempted my own follow up, but the
      object was not visible due to its low altitude.

      I was in contact with Tim at MPC before I finished up for the night and
      he had place B44E on the page.

      When I awoke, Rob's follow up obs were in my inbox as was a note from
      Tim stating that it was likely man-made and the object was now on the
      Space Junk page. He also commented that with Rob's follow up, the orbit
      fell in place rather nicely and that one more set of obs from me that
      night would be sufficient to nail it down. Tim had also said that he had
      alerted Chodas & Chesley for their input.


      I ran my obs through Bill Gray's Sat_ID with the latest TLEs and came up
      with nothing. Finding a candidate being placed on the "elsewhere" page
      as "Not a minor planet" isn't uncommon. We are finding Bill Sat ID very
      helpful in culling out man-made objects, so they don't get submitted and
      put up on the page, but I hadn't run these obs through before sending
      them off to MPC.

      After that I sent all of the obs on to Tony Beresford as I thought he
      would appreciate the challenge of figuring out what this might be. Being
      more knowledgeable about satellites, I figured he'd nail it down rather
      quickly.

      Rob had sent his obs to Bill Gray and at Rob's request, I sent mine
      along to him as well.

      Using the ephemerides from the Space Junk page, I scheduled additional
      observations for last night. Shortly before the object rose above 30
      degrees, Tony sent an ephemeris that he had produced. The two were very
      similar, within arc seconds.

      After obtaining and submitting two more sets of obs, I sent those
      results to Tony, who in sort order came up with the current 80.x day
      geocentric orbit.

      B44E will be visible in larger telescopes for a few more weeks, then
      fading to 26th magnitude, until early November when it'll brighten again
      to around 21st magnitude.

      I'd like to thank Tony and Bill for their efforts.

      It isn't surprising this flying desk hasn't been spotted earlier.
      It'll be interesting to find out if it's a product of NASA or nature.


      --

      (Opinions expressed by me are my own. They may not reflect those of my
      employer and should not be mistaken as official statements.)

      ********************************
      Richard Kowalski
      Catalina Sky Survey
      Lunar and Planetary Laboratory
      University of Arizona
      Tucson, AZ 85719
      ********************************
    • Paul W. Chodas
      This object is clearly in orbit around the Earth, but the orbit is very distant and therefore quite unstable. I get a slightly shorter orbital period, about
      Message 2 of 4 , Aug 29, 2006
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        This object is clearly in orbit around the Earth, but the orbit is very
        distant and therefore quite unstable. I get a slightly shorter orbital
        period, about 78 days, a perigee well beyond 1 lunar distance, and apogee
        at about 2 LDs. This, together with the fact that the geocentric orbit
        plane is currently inclined about 60 degrees to the ecliptic, suggests to
        me that B44E is a captured object. The whole situation is very reminiscent
        of J002E3, which was identified as the captured Apollo 12 S-IVB third
        stage. This object, however, is much fainter: if it is a rocket stage, it
        is must be a small one, such as an Agena, Centaur, IUS or Luna.

        Like Bill, I ran the object backward in time, but the data arc is really
        too short to say with much certainty when the object was captured. All
        that can be said right now is that it has been orbiting the Earth for at
        least a couple years, and will continue to do so for at least three more.

        Perhaps the reason we haven't seen this object until now is that it passes
        through oppposition region in a direction nearly perpendicular to the
        ecliptic and traverses the region in just a couple days.

        Paul
      • Bill J Gray
        Paul Chodas wrote: ... I get a slightly shorter orbital period, about 78 days... I shouldn t have given an orbital period of 80 days, plus or minus a small
        Message 3 of 4 , Aug 30, 2006
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          Paul Chodas wrote:

          "... I get a slightly shorter orbital period, about 78 days..."

          I shouldn't have given an orbital period of "80 days, plus or minus
          a small fraction", without specifying the epoch. At epoch 2006 August
          21, the period (based on the osculating orbit, and including only the
          mass of the earth) is 72.36 days. For an epoch of 31 August, it's
          80.14 days. Just a matter of where the moon happens to be at the time.

          "...Perhaps the reason we haven't seen this object until now is that
          it passes through opposition region in a direction nearly perpendicular
          to the ecliptic and traverses the region in just a couple days."

          Yup. I was originally puzzled as to how this guy could have been
          floating around for three to ten years (rough guess based on the dozen
          virtual dwarf asteroids/virtual space junk orbits I tried) without being
          detected, but then I looked at a few of the ephemerides... it usually
          doesn't come this close to opposition. This was a good apparition,
          near perigee and opposition at the same time.

          A reminder: the Usual Suspects would like to see any astrometry
          people get for this object. So please e-mail your astrometry to:

          mpc@...
          astrometry_distro@yahoogroups.com

          Anything e-mailed to the latter address will, of course, appear
          for all to see on the astrometry_distro Yahoo group:

          http://groups.yahoo.com/group/astrometry_distro/

          Again, ephemerides can be generated for this object from:

          http://cfa-www.harvard.edu/iau/SpaceJunk/SpaceJunk.html

          -- Bill
        • Jon Giorgini
          Ephemerides for 6Q0B44E can now be obtained from Horizons, based on a solution Paul Chodas just provided. This includes a nominal solar radiation acceleration
          Message 4 of 4 , Aug 30, 2006
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            Ephemerides for 6Q0B44E can now be obtained from Horizons, based on a
            solution Paul Chodas just provided. This includes a nominal solar radiation
            acceleration model.

            If you obtain additional astrometry, please copy Paul.Chodas@...
            on the MPC submission. No need to copy me.

            It was added to Horizons as a "spacecraft" for software reasons ONLY; this
            is NOT a conclusion regarding it's nature. So web users will find it under the
            "spacecraft" menu. Telnet and e-mail users can access it as 6Q0B44E, or
            "B44E" for short. Or "B4", for that matter.

            http://ssd.jpl.nasa.gov/horizons.cgi
            telnet://ssd.jpl.nasa.gov:6775
            email: ftp://ssd.jpl.nasa.gov/pub/ssd/horizons_batch_example.long

            Because it had to be added as a spacecraft, you won't automatically get plane
            of sky uncertainties.

            However, the orbit and covariance are on the orbit data sheet, so you can
            just cut-and-paste them back into the program. It will then think it is
            an asteroid and compute the uncertainties.
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