Can satellites wabble?

Robert H. McNaught (
Mon, 18 May 1998 11:42:47 +1000 (EST)

The 1.2-m UK Schmidt Telescope recorded several satellites every night of
operation.  I must have examined some several thousand satellite trails on
Schmidt plates and the only occasions a "wabble" was visible was on the rare
occasion when there were drive problems.  Visual examination could detect
deviations of a couple of arcseconds, and with wabble due to drive error,
the stars were always elongated in R.A.  Depending on the direction of motion 
of the satellite, these "wabbling" satellites could appear sinusoidal or have 
a saw-tooth pattern.

Having said that, there were some flashing trails that DID "wabble".  They
were dead straight at their base magnitude, but showed a systematic drift in
the position of the centre of the flash from one side of the trail to the
other.  This was around the 2 arcsec level.  Simple maths suggests this
represents a few metres for low satellites, so I assumed this was the Sun's
reflection travelling across an elongated surface.  There may be some other

I never saw a meteor trail with any indication of deviations around the
arcsecond level and I saw many tens of meteor trails.  It would surprise me
if any instrumental record of a "wabbling" meteor was due to intrinsic
motion; camera shake from shutter vibration, wind, or from an inadequately
damped rotating shutter seeming the likely causes.

Cheers, Rob McNaught