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Impactor 2008 TC3 possibly recorded infrasonically?

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  • Matson, Robert D.
    Hi All, I thought I d check the Global Seismic Network to see if the sonic boom of the entry of 2008 TC3 was recorded on infrasound. The four closest stations
    Message 1 of 5 , Oct 7, 2008
      Hi All,

      I thought I'd check the Global Seismic Network to see if the sonic
      boom of the entry of 2008 TC3 was recorded on infrasound. The four
      closest stations in Africa have codes BGCA, KDWA, FURI and RAYN:

      http://aslwww.cr.usgs.gov/Stations/gsn_map.gif

      I was only able to find online telemetry data for FURI which is the
      Mt. Furi, Ethiopia station. FURI's station information is:

      http://www.fdsn.org/station_book/IU/FURI/furi.html

      Specifically, they are located at 8.903N, 38.6883E, altitude 2545m.
      This is about 1430 km away from 20.6N, 33.1E -- a rather long
      distance to have much hope of recording a bolide sonic boom. But
      just in case, I estimated what the approximate time delay should
      be. Assuming a speed of sound of 331 m/sec (the velocity in dry
      air at 0 C), the time to cover 1430 km would be 1 hour 12 minutes.
      The actual arrival time could vary quite a bit from this since
      the sound path is very non-linear. 1 hour 12 minutes after
      atmospheric impact at ~2:45:30 would be 3:57:30 UT. Well, take
      a look at the trace:

      http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/FURI_24hr.html

      Could that squiggle at 3:51 be it? It's a bit early (meaning
      the speed of sound would have to be higher, or the impact location
      closer), but it seems a bit coincidental that the only signature
      on the trace for the last 24 hours that looks anything like a sonic
      boom occurred within 6 minutes of the expected time.

      --Rob
    • Shepard, Michael K
      I ve got to tell you all that I m getting a charge out of seeing this entire thing unfold. Even better, I m using it (posts from MMPL) in my planetary science
      Message 2 of 5 , Oct 7, 2008
        I've got to tell you all that I'm getting a charge out of seeing this entire thing unfold. Even better, I'm using it (posts from MMPL) in my planetary science class as an object lesson in how science is done in real time.


        Michael K. Shepard
        Dept. of Geography and Geosciences
        400 E. Second St.
        Bloomsburg University
        Bloomsburg, PA 17815
        570-389-4568

        From: mpml@yahoogroups.com [mailto:mpml@yahoogroups.com] On Behalf Of Matson, Robert D.
        Sent: Tuesday, October 07, 2008 3:32 PM
        To: mpml@yahoogroups.com
        Subject: {MPML} Impactor 2008 TC3 possibly recorded infrasonically?


        Hi All,

        I thought I'd check the Global Seismic Network to see if the sonic
        boom of the entry of 2008 TC3 was recorded on infrasound. The four
        closest stations in Africa have codes BGCA, KDWA, FURI and RAYN:

        http://aslwww.cr.usgs.gov/Stations/gsn_map.gif

        I was only able to find online telemetry data for FURI which is the
        Mt. Furi, Ethiopia station. FURI's station information is:

        http://www.fdsn.org/station_book/IU/FURI/furi.html

        Specifically, they are located at 8.903N, 38.6883E, altitude 2545m.
        This is about 1430 km away from 20.6N, 33.1E -- a rather long
        distance to have much hope of recording a bolide sonic boom. But
        just in case, I estimated what the approximate time delay should
        be. Assuming a speed of sound of 331 m/sec (the velocity in dry
        air at 0 C), the time to cover 1430 km would be 1 hour 12 minutes.
        The actual arrival time could vary quite a bit from this since
        the sound path is very non-linear. 1 hour 12 minutes after
        atmospheric impact at ~2:45:30 would be 3:57:30 UT. Well, take
        a look at the trace:

        http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/FURI_24hr.html

        Could that squiggle at 3:51 be it? It's a bit early (meaning
        the speed of sound would have to be higher, or the impact location
        closer), but it seems a bit coincidental that the only signature
        on the trace for the last 24 hours that looks anything like a sonic
        boom occurred within 6 minutes of the expected time.

        --Rob



        [Non-text portions of this message have been removed]
      • Quanzhi Ye
        Fantastic! As far as I know it s the first time of human being to observe such event. Quanzhi ... into
        Message 3 of 5 , Oct 7, 2008
          Fantastic! As far as I know it's the first time of human being to
          observe such event.

          Quanzhi

          --- In mpml@yahoogroups.com, "Reiner M. Stoss" <rstoss@...> wrote:
          >
          > Folks,
          >
          > after Roy Tucker suggested that someone should observe this
          > object's entry into Earth' shadow, and Pasquale Tricarico posted
          > the predicted times for this event, we sent two telescopes at J75
          > to record it.
          >
          > We had tracked the object already for hours and had just stopped
          > doing astrometry because the timing got an issue with this
          > extremly fast mover.
          >
          > Both telescopes were able to simultaneously record the
          > event. Each one did a 6min exposure, allowing 2008 TC3
          > to trail approximately 0.75 degrees and thus to remain well inside
          > the 1.5 degrees field of view. However, after only 0.4 degrees
          > the trail is becoming invisible, confirming the predicted entry
          into
          > Earth' shadow.
          >
          > An image section spanning one third of the original 1.5 deg
          > image in width is available on this page:
          >
          > http://www.minorplanets.org/OLS/2008_TC3/
          >
          > Cheers,
          > Reiner
          > J75 LSSS
          >
        • Roy Tucker
          Yes, it was fabulous! ... From: Quanzhi Ye To: Sent: Tuesday, October 07, 2008 4:39 PM Subject: {MPML} Re:
          Message 4 of 5 , Oct 7, 2008
            Yes, it was fabulous!

            ----- Original Message -----
            From: "Quanzhi Ye" <tom6740@...>
            To: <mpml@yahoogroups.com>
            Sent: Tuesday, October 07, 2008 4:39 PM
            Subject: {MPML} Re: Impactor 2008 TC3 entering Earth' shadow


            > Fantastic! As far as I know it's the first time of human being to
            > observe such event.
            >
            > Quanzhi
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