R: North Korea satellite: retrograde ground track displayed in launch control centre

From: satrack@libero.it
Date: Wed Apr 11 2012 - 09:43:10 UTC

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    I have included Ted's TLE into a temporary page. 
    Tracking can be attempted at the following link:
    >----Messaggio originale----
    >Da: ssl3molcz@rogers.com
    >Data: 11-apr-2012 3.36
    >A: <seesat-l@satobs.org>
    >Ogg: North Korea satellite: retrograde ground track displayed in launch	
    control centre
    >Included in some of the video shot by journalists covering North Korea's 
    upcoming rocket launch, are launch control
    >display screens depicting a southbound ground track that to the eye looks 
    close to that of a sun-synchronous satellite
    >orbit. It has been discussed on the NSF and NK forums. I have been working to 
    estimate the orbit implied by the ground
    >track and to evaluate its consistency with the location of the launch site, 
    NOTAMs, and other information issued by
    >North Korea.
    >The first images I saw had insufficient resolution or coverage to confidently 
    estimate the orbit. Fortunately, late last
    >night Charles Vick informed me of the following video, which is the clearest 
    I have seen yet:
    >The relevant scene appears for several seconds beginning at 01:56 elapsed 
    >Notice that the track begins on the other side of the Earth, rises above the 
    northern limb, then proceeds south over
    >China, the Korean peninsula and so on. The track appears to be a 3D 
    representation of the initial orbit around the
    >Based on a notional launch on 2012 Apr 12 at 02:30 UTC, and assuming a 500 km 
    circular orbit, I estimate that the orbit
    >is inclined approximately 94.5 deg:
    >1 79802U          12103.11415511  .00000000  00000-0  00000-0 0    05
    >2 79802  94.4500 182.0500 0002000 359.9726 179.8827 15.21000000    00
    >I estimated the inclination and RAAN by trial fit to a couple of reasonable 
    clear land marks visible on the display.
    >Since the orbit has been plotted as a 3D representation, there is potential 
    for parallax error in the ground track, but
    >it is mitigated by the more or less perpendicular vantage point. I estimate 
    the RAAN and inclination are accurate to
    >within several tenths of a degree.
    >The epoch is of no special significance; it and the mean anomaly have been 
    chosen to place the orbit near the launch
    >site about 4 min after lift-off, which is a useful rule of thumb to estimate 
    the location of a newly satellite within
    >its orbit.
    >I was especially interested to determine whether the 94.5 deg orbit 
    intersects with the 88.7 deg inclined ascent
    >trajectory, and whether the location is plausible for the 3rd stage firing. 
    Here is a plot of both trajectories:
    >Here is a view near the ascent trajectory:
    >The point of intersection is near 28.25 N, 124.5 E, about 1270 km downrange 
    of the launch site, which seems to be in
    >rough agreement with the plot of altitude vs. range in this recent analysis 
    by David Wright (see Fig.2):
    >The orbit is not sun-synchronous, but better than the 88.7 deg orbit implied 
    by the NOTAMs, for the stated purpose of
    >the satellite. Sun-synch orbits precess +0.9856 deg/d. The 88.7 deg orbit 
    would precess at -0.1730 deg/d; the 94.5 deg
    >orbit would precess 0.5917 deg/d.
    >To be precisely sun-synch, a 500 km orbit must be inclined 97.4 deg. The 
    apparent nearly 3 deg deficit may be an
    >indication of the performance limitation of the launcher. I do not exclude 
    the possibility that the displayed track was
    >faked to mislead the news media, but it should not have been more difficult 
    to produce a high-fidelity fake, assuming
    >the work was done by the trajectory specialists. Considering the relative 
    position of the numerals 4 and 7 on a keypad,
    >a simple, honest typo also cannot be excluded.
    >Ted Molczan
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