RE: More details Re: Re-entry of Chinese 14-049C seen over the Atlantic

From: Ted Molczan via Seesat-l <>
Date: Sun, 28 May 2017 21:37:01 -0400
I used GMAT 2015a to propagate the final USSTRATCOM TLE of 14049C / 40120 to decay. For convenience, I have embedded the
GMAT output trajectory into an ephemeris generating spreadsheet, which can be used to evaluate sighting reports from
fixed locations:

The spreadsheet opens to an ephemeris at 5 s time intervals for the co-ordinates of the aircraft shortly after the
sighting. (If the position of the aircraft at each of the ephemeris times were available, then the spreadsheet could be
modified to use that data, which would yield somewhat greater accuracy.) Ephemerides for other fixed locations can be
computed by editing the co-ordinates at col 15, rows 2-4.

The altitude of the re-entry trajectory is approximate. If anyone can identify the star background sufficiently to
extract celestial co-ordinates along the re-entry trail, then I could attempt to adjust the analysis to obtain a better

Column 8 states the elevation relative local horizontal; col 9 relative the horizon. The approximately 3.3 deg
difference is due to the high altitude of the aircraft.

The pilot provided Marco Langbroek with a photo of the aircraft instruments taken about 1 min. after the sighting. Marco
reported that the displayed time was 23:20:49 UTC. He also determined that the aircraft's heading was 219 deg. (Was this
true or magnetic?) From the photos, the re-entry fireball travelled from right to left. 

The pilot spotted it abeam the aircraft, which would have been near azimuth 309 deg. The ephemeris puts that a few
seconds before 23:16:30 UTC. Elevation was about 24 deg above the horizon. Slant range about 195 km.

The pilot reported that the objects disappeared on the horizon. Assuming that occurred 1 min. prior to the
aforementioned time of the photo of the instruments, than the time was near 23:19:49 UTC. The corresponding elevation in
the ephemeris is just 0.5 deg above the horizon. That makes the sighting duration about 3 min., which is about 1 min.
longer than reported. 

Overall, there is very good agreement between the sighting and the re-entry, given the uncertainty in the observed time
and duration, and the re-entry trajectory.

The closest slant range to the trajectory was less than 180 km, near 23:16:40 UTC.

The GMAT script is here:

To use the script, it will be necessary to edit the file paths at line 53 and 58. The latter points to a file of space
weather data, named sw19571001e.txt. It consists of data downloaded today from Dr. T.S. Kelso's CelesTrak site, which I
renamed by appending "e". Use the contents of either of the two space weather data files on the following page:

Ted Molczan

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Received on Sun May 28 2017 - 20:37:52 UTC

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