Last updated 14 Sep 2017

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Man made Satellite Gallery

GS428A (very fast moving object)

Picked up on two frames exposed for a NEOCP object this very fast moving object has not been able to be identified with a known artificial satellite (though it is very likely to be one, see below)

The two frames were exposed unbinned, the full field being 25'x25' and pixel scale 1.5"/pixel.

2004 Feb 08 01:40:55-01:41:25
2004 Feb 08 01:42:10-01:42:40

and astrometry for the start and end positions for each trail is as follows:

GS428A C2004 02 08.07008107 48 19.71 +56 39 06.9 J95
GS428A C2004 02 08.07042807 48 47.01 +56 35 31.7 J95
GS428A C2004 02 08.07094907 49 27.93 +56 30 06.4 J95
GS428A C2004 02 08.07129607 49 54.24 +56 26 36.0 J95

Clouds stopped follow up immediately after the trails had been recognised and searches two hours later when the clouds started to break failed to recover the object. Gary Hug also performed searches for the object but also failed to find it.

On close examination the trails are not continuous, but made up of discreet points. The object appears to have been varying in brightness with a period of about five seconds, with four or five flashes per period. Travelling at 10.3"/second, these flashes must have lasted no more than 0.5 seconds, quite likely shorter to not appear elongated.

Measuring the brighter flashes gives a magnitude of about +16.0, but because these flashes are about 100 times shorter than the stars were exposed for indicates that these flashes may have been up to five magnitudes brighter, or approximately mag +11 or 12. Images taken in later days with short exposures of 1 second have confirmed that the flashes reach at least mag +12.

Below are enlargements of the two trails and intensity profiles showing the change in brightness.

Movement is top right to bottom left in the images and left to right in the line profiles.


Tony Beresford and Bill Gray determined that it was likely to be in a Molniya-like orbit (used for communications satellites etc.) and Tony also suggested that the object would pass close by its original discovery location just under 24 hours later at 01:32UT on 09th Feb 2004.

The sky was again clear at that time and frames were taken, centred on the mid-position of the previous night's two images. Four minutes after Tony's prediction the object once again passed through the field of view, with its distinctive string of points appearance, remarkably close to its path from the night before!

The image below has been created by combining two images from Feb 8th and two from Feb 9th, both nights showing the same star field. The object passed just 66 seconds south of its path from the previous night. As the images from the second night were binned 2x2 they are more intense and therefore appear brighter than the two images from the 8th.

With an additional set of 10 astrometric positions obtained from a series of 1 second exposures taken later on the 9th Feb 2004 and sets taken on 10.98 and 11.07 Feb, Mike McCants was able to determine the following two line elements, showing that this is indeed in a Molniya type orbit, although still no identification with a known satellite has been conclusively made.

1 99991U          04041.82480028  .00000000  00000-0  00000+0 0    00
2 99991  65.0472 349.7554 6963856 273.5234  80.4205  2.00707072    03


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