Re: Observed Lunar transit -- what did I see?

From: Jim Scotti (
Date: Thu Oct 16 2003 - 17:52:55 EDT

  • Next message: "Re: Observed Lunar transit -- what did I see?"

    Hi David,
        Looking at your simulation, my first thought was that it looked a bit
    like the Hubble Space Telescope (particularly if the solar panels were in the
    right orientation so that they were not visible or maybe only slightly
    visible as you suggest might have been the case).  I know there are a few
    people on this list who will likely jump right in to help you ID this
    satellite.  One thing they could use is your location (at least
    approximately, if not with the accuracy of a fellow technology geek like me
    who has his GPS handy).  You could probably also use one of the satellite
    ephemeris services like Heavens Above to look for any satellites that were
    close to the right location for you.
        Good luck and welcome to the SeeSat-L group!
    On Thu, 16 Oct 2003, David Ellsworth wrote:
    > Hello All,
    > I am new to this list, having seen my first lunar transit by a pure fluke 
    > last night!
    > I got a new 4" refractor a few days ago, and I was admiring the Moon at 
    > 65X. Then I saw this beautiful silhouette start to cross the disc... it was 
    > SO detailed. Taking a lazy 15-20 seconds to cross, I got a wonderful look 
    > at it! It was vertically oriented and had a clear separation between top 
    > and bottom halves; the top was narrow and the bottom was wider. The sides 
    > had visible detail in them -- they were not smoothly straight -- but in awe 
    > as I was  I did not think to make a mental snapshot and a quick sketch.
    > The crossing ended at 15 Oct 23:35:30 after crossing the Moon (altitude 
    > 19-d 37') from left to right and slightly upward oriented to the horizon, 
    > which translates to North-South and slightly West. Its velocity did not 
    > perceptible waver, and it became invisible after crossing the sunlit 
    > portion of the moon. I would estimate it to be 10-15 arc seconds in 
    > apparent height.
    > Here is an approximate simulation of what I saw: 
    > The simulated satellite is intentionally not antialiased, because there was 
    > a sharp delineation between top and bottom halves.
    > It is an amazing feeling to have seen something that nobody else on Earth 
    > saw! This has to be a virtual guarantee given how sensitive transits are to 
    > location.
    > I have not been able to find it using either J-Pass or CalSky. Is it 
    > possible I saw a satellite not in their databases? Given how long it took 
    > to transit, it would have had to be very far and therefore VERY large... IF 
    > it was moving perpendicular to me. Is it possible its path was extremely 
    > foreshortened because it was moving toward me?
    > Or is it more likely that it wasn't a satellite? I'm open to speculation. 
    > What could it have been? The mystery of the thing is driving me nuts!
    > Regards,
    > David
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    Jim Scotti
    Lunar & Planetary Laboratory
    University of Arizona
    Tucson, AZ 85721 USA           
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