Mystery tracks through M42

Matson, Robert (ROBERT.D.MATSON@saic.com)
Wed, 6 Oct 1999 19:35:14 -0700

Hi All,

Last week I finally got around to picking up the latest issue
of Sky & Telescope so that I could check out that M42 photo
for myself.  Now that I see the "clean" image, I can make some
more concrete observations.

1.  The east-west tracks are very likely GEO satellites, as we
all surmised.  One of the four satellites (the southern-most)
was near the center of the frame at the beginning of the
exposure, and thus its track is only visible to the east of
the nebula.

2.  The north-south tracks are NOT satellites.  No bright
satellites were moving exactly N-S near M42 at any time on
March 7, 1999, as seen from Kelly, NC.  (I also checked
March 6th, in case there was a UT-local date issue).  These
are BRIGHT tracks (not to mention perfectly parallel, and
the same brightness), and could not have been produced by
any small debris objects that might be missing from the
8100+ catalog.  Also note the difference in color:  the
E-W tracks are white/gray; the N-S ones are reddish.

So, I think we're talking about something atmospheric.  The
angular separation is about 0.05 degrees.  If the date and
time reported are correct, then M42 was about 40 degrees
above the horizon at the start of the picture, and 34 degrees
by the end.  For an aircraft in level flight at, say,
30000 feet, at an elevation of 37 degrees headed directly
toward the observer, the separation of the sources producing
the tracks would be:

2 * TAN(0.025) * 30000 / SIN(37) = 43.5 feet.

This assumes the flight direction is perpendicular to the
observer's horizon.  However, from the photo we know that
it was tilted about 45 degrees relative to the observers
horizon which means the actual separation of the lights is
at least 1.4 times greater, or 61 feet.  (It'll actually
be greater than this due to foreshortening, but since we
don't know the altitude for sure, no sense getting too
bogged down with details.)

So, is there any aircraft out there that has a red light
on each wing, with a light separation on the order of
60 feet (and no other bright lights)?  Doesn't sound like
any commercial jet I've seen... --Rob