Re: Mystery tracks through M42
Dale Ireland (direland@drdale.com)
Wed, 6 Oct 1999 19:57:42 -0700
That's just what I said to Sky and Telescope, they responded with "how
do you know there were no satellites that night with a north-south path
because only a portion of known sats have published elements".
Dale Ireland
Astronomy Page http://www.drdale.com
Comets, Satellites, Eclipses, Photography, Fabrications
----- Original Message -----
From: Matson, Robert <ROBERT.D.MATSON@saic.com>
To: SeeSat-L <SeeSat-L@blackadder.lmsal.com>
Sent: Wednesday, October 06, 1999 7:35 PM
Subject: Mystery tracks through M42
> 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
>