Vanguard 1

Date: Mon May 12 2003 - 22:31:35 EDT

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     On 8 May, Tom Wagner, in his quest to "catch" the oldest orbiting antique,
    Vanguard 1, wrote:
     >Hi Rich.
     My message was posted on March 21, 2003. I really appreciate the reply. In my
    message I quoted the following.
     "Vanguard 1 is very faint visually, between tenth and fifteenth magnitude."
     I looked up your location and see that it looks like you are in a dark area.
     Is that correct? My night sky, even in the country, isn't all that good.  My
    largest scope is an 8" f10. I wonder if I could see it with that scope w/o the
    reflections that you saw.
     What do you think?
     Clear skies, Tom  Iowa  USA
     Hi Tom -
     Here's what I think, based on my experience....
     I'm in a fairly dark location, at 2728 meters, but being only 20 miles from
    the lights of Denver (2 million population), the sky to the east is
    distressingly bright.  I've seen down to magnitude 15.9 with my 12-inch
    reflector, but that was a star, not a moving satellite.
     Vanguard 1 has reached 10th magnitude or so on several of the occasions I've
    seen it, well within the reach of an 8-inch telescope (whose limiting magnitude
    is about 1 mag. brighter than a 12-inch).  I'd say with a 28 or 32 mm wide
    field eyepiece, and a field of view of a degree, you'll catch the little
    grapefruit on, say, one out of 2 or 3 attempts.  You'd be catching reflections
    off the solar panels, since the specular reflection off the sphere is quite
    faint.  On the two occasions when I successfully tracked Vanguard it was
    magnitude 12 to 14 between flashes.
     I use a standard magnitude of 10.3 with Quicksat to predict passes of
    Vanguard, and the resulting magnitude predictions are pretty close to the
    sphere reflection magnitude.  The flashes can be 2 or 3 magnitudes brighter.
     Good luck!
     Cheers, Rich Keen, Coal Creek Canyon, Colorado, USA (39.877N, 105.391W, elevation 2728m)
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