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Re: {MPML} 2008 EZ7 and NEA BJ19377 similarity

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  • Reiner M. Stoss
    Dmitry, Denis, group, ... Any news? We tracked 2008 EZ7 tonight from station 620 and it was at 9h RA, where it was supposed to be. BJ19377 however is confirmed
    Message 1 of 5 , Mar 8, 2008
      Dmitry, Denis, group,

      > Denis Denisenko pointed out that inclination and perihelion distance
      > of 2008 EZ7 and BJ19377 (see NEO confirmation Page) are very similar.
      >
      > I recognized that other angular elements of these two objects are very
      > similar, too. Thus, these objects are clearly related.

      Any news?

      We tracked 2008 EZ7 tonight from station 620 and it was at 9h RA,
      where it was supposed to be. BJ19377 however is confirmed at 7h RA.
      So how exactly could they be "clearly related"?
      Something like Rosetta and "The son of Rosetta"?

      Tracking 2008 EZ7 was fun though. 4.7"/s, R 14.0, 22° altitude.
      Slewed the telescope to the MPES ephem, 10s exposure
      and there it was, almost 1 arcmin long trail.
      Slewed the telescope a few minutes ahead on track (ambush style)
      and started consecutive 1s exposures for astrometry. Object entered
      the field and crossed it in less than six minutes.

      Reported to MPC and Bill Gray.

      Now, about 5h later, the object should have brightened by 1.7mag
      and more than doubled its speed. And much better observable at 41° alt.
      I have a problem though... to avoid too much trailing, I would need
      to expose only a fraction of a second (~0.3-0.4s), but the remote control
      software allows only integer seconds for the exposure length :-))

      Hmm... tracking at half the object motion would make 1s exposures
      possible again, splitting the motion between object and stars.
      But non-siderial tracking is also not possible to the needed precision
      with the used mount (classical LX200).

      For LC work, a telephoto lense might be the best. Similar to the setup
      that Richard Miles is using.

      Regards,
      Reiner
      620 Observatorio Astronomico de Mallorca
    • Bill J Gray
      Hi Dmitry, all, I got the following elements for BJ19377: Orbital elements: BJ19377 Perihelion 2008 Mar 11.674505 TT = 16:11:17 (JD 2454537.174505) Epoch 2008
      Message 2 of 5 , Mar 8, 2008
        Hi Dmitry, all,

        I got the following elements for BJ19377:

        Orbital elements:
        BJ19377
        Perihelion 2008 Mar 11.674505 TT = 16:11:17 (JD 2454537.174505)
        Epoch 2008 Mar 1.0 TT = JDT 2454526.5 Earth MOID: 0.0036
        M 356.824 (2000.0) P Q
        n 0.297455 Peri. 1.809 -0.989407 -0.143196
        a 2.222565 Node 169.863 0.131428 -0.953328
        e 0.55156 Incl. 7.781 0.061641 -0.265817
        P 3.31 H 24.6 G 0.15 q 0.996679 Q 3.448451
        From 17 observations 2008 Mar. 8-8 (16.7 hr); RMS error 0.801 arcseconds

        ...which can be compared to
        http://home.gwi.net/~pluto/mpecs/mpec.htm#elements . To compare
        apples to apples, look at the "before earth encounter" elements:
        peri=1.8, node=168.8, incl=9.2. But a=1.83, e=.46. It's hard to
        see this as a for-real match.

        Reiner, thanks for the tip on NEOCP. I can get the data on
        maybe one try in five. Guess I just wasn't persistent enough before.

        -- Bill
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