RE: Help needed identifying possible reentry on Feb 2, 2015

From: Ted Molczan via Seesat-l <seesat-l_at_satobs.org>
Date: Wed, 4 Mar 2015 10:24:09 -0500
Ron Lansing wrote:

>  My stationaery camera caught this activity, any ideas what it was.
> First, I thought it was a meteor, but now not so sure.
> I have not been able to correlate elsewhere.
> 
> Object burns in over Surprise AZ on Feb 2, 2015 at 829PM MST.
> 
> Az = 325.301, El = 49.593, looking NW towards constellation Cassiopeia.
> 
> This is an image of the object before it started to re-enter. It appears to have a rocket
> nozzle?
> 
> https://www.flickr.com/photos/128127307_at_N06/16433430860/
> 
> This is the video of re-entry and some frames after.
> 
> http://youtu.be/8A9vqjwgSJE

It's a nice video of a meteor.

I estimate the visible trajectory across the sky as follows:

              R.A.   Dec.    Az  EL
             hh:mm   deg    deg  deg
Appeared     02:07, +53.8  317.9 28.5
Disappeared  01:18, +52.2  319.5 21.1

The visible trajectory spanned about 7.5 deg. The time to traverse was about 1.3 s, which yields an angular velocity of
about 5.8 deg/s.

The greatest angular velocity of a typical re-entry from low Earth orbit, as seen from the surface of the Earth, occurs
when object has descended to about 72 km. Observed from a point directly below, at sea-level, the angular velocity would
be about 5.3 deg/s. Observing from 2500 m altitude would increase this to about 5.5 deg/s.

Ron's object was far from the zenith, and still moved at a faster angular velocity than the maximum of a re-entry. A
re-entry observed at that elevation would move no faster than about 1 deg/s. Therefore, the object must have been a
meteor.

The video imagery is of too low resolution to resolve details the size of a rocket nozzle. The greatly magnified video
frame linked above, and those presented at the end of the video, cannot possibly reveal any useful detail about the
object.

Ted Molczan


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Received on Wed Mar 04 2015 - 09:24:53 UTC

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