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I 'Oumuamua detection date and ramifications for a big asteroid collision with the Earth

  1. Jan 6, 2018 #81

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    I don't believe this. TCAS is 70 W at 1.03 GHz. At 35 ly (roughly where there are 1000 stars) this works out to 10-10 photons per second per square meter at the earth. You won't see a signal at all, much less pull it out of the noise.
     
  2. Jan 6, 2018 #82

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    Did you take the directionality of the antenna into account?
    70 W is significantly lower than what I found.

    The number is still quite low.
     
  3. Jan 7, 2018 #83

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    Yes, but I took their claim very literally. Aircraft radar means "one aircraft", it means "civilian aircraft" (e.g. not an AWACS), it means "mounted on the aircraft" and it means "pointing where the aircraft wants", which in turn means integrated over time it's covering 4π.
     
  4. Jan 7, 2018 #84
    TCAS isn't radar. It's a transponder based interrogtate-and-respond system, basically just a radio system. I think some do aircraft have weather radars that operate at 10k+ Watts. Maybe this is what they're talking about? Their web site really doesn't explain much.

    Traffic collision avoidance system
     
  5. Jan 7, 2018 #85

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    I would argue it is radar, although via transponder and not reflection. But I agree that the web site is sufficiently vague to keep us guessing. I would say that to take a military radar out of the plane, and hooking it up to a polar mounted radio telescope and to transmit towards earth is either a) not what they mean, or b) what they mean, but they are being misleading.
     
  6. Jan 10, 2018 at 2:34 PM #86
    This was posted on the arXiv last evening.
    Breakthrough Listen Observations of 1I/'Oumuamua with the GBT
    Eight hours of observations didn't find any artificial transmissions. While it's good to know that it probably wasn't aliens, I can think of better uses for the GBT.
     
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