Re: [dsat] Resurs 1-3 Solar transit

From: Bjorn Gimle (
Date: Mon May 12 2003 - 05:20:27 EDT

  • Next message: Tony Beresford: "Fwd: Re: identification help"

    If transit took 0.86s, why don't you see it in more than one frame at 15
    fps ?
    Does the Sun fill your webcam image (or what % of the image/Sun)?
    If your webcam delivers 480 vertical pixels, and the Sun (apparent size
    18 km at 2000 km range) fills the image, the distance between pixels is
    36 m.
    So a smaller rocket (also moving 5 m during exposure) would not always be
    completely within a pixel, and then only reduce the image intensity to
    some 90%, not completely black, but it would of course look as big as one
    ----- Original Message -----
    > It passed across the lower half of the Sun's disk at 18:30:26 gmt
    > in one frame of AVI (1/2500th sec 15fps ) as a small blur traversing
    > of the main sunspot cluster , presently visible.
    > I was using a webcam / 200 mm zoom lens combination fitted with Baader
    > I am however uncomfortable with the size of the target.
    > Last week I imaged a solar transit by a Cosmos rocket booster using the
    > set-up.Again , the object seemed to be too I have a couple
    > questions.
    > what causes this apparent magnification.....the booster is after all
    > 10.4 metres in length and has a range of nearly 2000 km.
    > Details from are as follows.
    > 19h30m29.4s Resurs 1-3 Rocket
    > (23343 1994-74-B) Crosses the disk of Sun. Separation:0.25d
    > Angular Velocity:12.9'/s.  Transit duration: 0.86s
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