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Just after local midnight of August 7-8, 2019, the South Korean amateur astronomer Mr Lee Won-Gyu was taking images of the night sky at Mount Jiri in Korea when he observed and photographed a cloud-like illuminating phenomena in Corona Borealis that to the expert eye is clearly the exhaust cloud from a rocket engine burn.

Mr Lee Won-Gyu's images of the cloud are featured in this article in the Korea Times, where they were presented as a 'UFO'. The images were taken between 00:14 and 00:24 Korean time (corresponding to August 7, 15:14-15:24 UT). Mount Jiri, the location of the sighting, is at approx. 35.34 N, 127.73 E. In this blogpost, I will identify this 'UFO' as a Chinese ICBM test.

Initial speculation on the internet was that this was perhaps related to the AEHF 5 geosynchronous satellite launch from Florida on August 8, 10:13 UT. The observation was however done 19 hours before this launch (there was some initial confusion due to the date difference in local time and UT), and the cloud was seen in a wrong part of the sky for a launch to geosynchronous altitude. So I suggested it could be a Russian or Chinese ICBM test launch.

As it turns out, additional evidence suggests this indeed was an ICBM test, by China. As the result of a private request by me, Twitter user @Cosmic_Penguin managed to dig up NOTAM's for the date and time of the event posted on a Chinese forum by a forum member nicknamed 'kktt'. These NOTAM's with temporary airspace closures from "ground to unlimited" in two parts of China corroborate an ICBM test launch:


A4092/19 NOTAMN
Q) ZBPE/QRTCA/IV/BO/W/000/999/3909N10940E019
A) ZBPE B) 1908071449 C) 1908071511
E) A TEMPORARY RESTRICTED AREA ESTABLISHED BOUNDED BY:
N392016E1092107-N391413E1100213-N385819E1095815-N390419E1091716
BACK TO START.VERTICAL LIMITS:GND-UNL. ALL ACFT SHALL BE FORBIDDEN
TO FLY INTO THE RESTRICTED AREA.
F) GND G) UNL


A4094/19 NOTAMN
Q) ZWUQ/QRTCA/IV/BO/W/000/999/3712N08311E108
A) ZWUQ B) 1908071451 C) 1908071548
E) A TEMPORARY RESTRICTED AREA ESTABLISHED CENTERED AT
N371133E0831033 WITH RADIUS OF 200KM. ALL ACFT ARE FORBIDDEN TO
FLY INTO THE TEMPORARY RESTRICTED AREA. VERTICAL LIMITS:GND-UNL.
F) GND G) UNL


The NOTAM's have a time window between 14:49 UT and 15:48 UT on 7 August 2019, which fits the phenomena observed from Korea (7 August 15:14-15:24 UT). They also fit the direction of the sky phenomena as seen from Korea: the exhaust cloud was seen at 30 degrees elevation in the sky at azimuth 290-291 degrees (west-northwest). This sightline points directly to the area designated in NOTAM A4092/19.

The map below plots the two areas designated in the NOTAM's. The smaller rectangular area from NOTAM A4092/19 represents the launch area near Hongjian Nur in Shaanxi province. The larger circular area from NOTAM A4094/19 at the southern edge of the Taklamakan desert represents the RV target area. The two areas are some 2300-2400 km distant from each other:

[Image] click map to enlarge
I have depicted the sightline from Mr Lee Won-Gyu's photographs from Mt. Jiri in Korea on the map as well (white): it points towards the launch area and it lines up with the direction of that rectangular area. Both time and direction therefore fit the Korean sighting. So does the character of the photographed cloud, which is similar to missile exhaust clouds observed during other ICBM launches.

This was an interesting ICBM launch in that it appears to have been highly lofted, with an apogee at approximately 3000 km altitude. This is based on both the estimated flightime (about 37 minutes) deduced from the NOTAM time window durations; and from an assessment of the exhaust cloud sightings from Korea, the direction and elevation of which point to a burn at 3000 km, close to apogee of the orbit, when combined with a ballistic trajectory between the two areas of the two NOTAM's. The launch happened near 15:00 UT (August 7), the missile engine burn seen from Korea happened some 15 minutes later close to mid-course and was probably meant to change the direction of the missile.

The situation is spatially depicted in the diagram below. The sightline from Korea crosses a 3000 km apogee trajectory twice, at about 2300 km altitude when the missile is ascending, and near apogee at 3000 km altitude. The latter altitude is the most likely location of the engine burn. At these altitudes, exhaust clouds are well above the earth shadow and hence brightly sun-illuminated.

[Image] click image to enlarge
When launched on a less lofted trajectory, this missile would have had a ground range of at least 6300 km. The reason to launch it into a lofted trajectory, rather than a more typical trajectory with apogee at 1200 km, is that in this way the test could be done completely within the borders of China. We have seen such lofted trajectories earlier with some early North Korean ICBM tests.

The ICBM appears to have done a dog-leg manoeuvre near apogee, changing the course just before mid-course. One piece of evidence for this is that the orientation of the launch hazard area from NOTAM A4092/19 does not match with a simple ballistic trajectory towards the target area. Neither does the sightline direction from Korea. They would result in a target area more to the north than the area from NOTAM A4094/19.

This can be well seen in the map, where I depicted both a direct ballistic trajectory (solid black line) between the two areas from the NOTAM's, as well as a 'dog-legged' trajectory (dashed black line), with the dogleg at the near-apogee burn imaged from Korea and initial launch direction according to the orientation of the NOTAM A4092/19 area:


[Image] click map to enlarge The direct trajectory clearly does not fit the launch area direction and Korean sighting well, whereas a launch into the direction of the NOTAM A4092/19 area and a dogleg near apogee does, with the latter also clearly fitting the Korean sighting.

A reason for such a dog-leg manoeuvre might be to confuse and evade mid-course anti-Ballistic missile intercepts. So I am wondering if this perhaps was an anti-ballistic missile test as well.

This missile test must in theory (and ignoring cloud cover) have been widely visible over Eastern Asia. The Korean Times article presents one other observation, also from Korea, but I have not seen other observations so far.

UPDATE: Twitter user @LaunchStuff sent me this link to a Weibo page, which includes several photographs of the event from various parts of China and a very cool video shot from Inner Mongolia, showing the spiralling behaviour seen during other ICBM tests as well.


Acknowledgement: I thank Ravi Jagtiani for bringing the Korea Times article to my attention; @Cosmic_Penguin for digging up the NOTAM's; and Jim Oberg and Jonathan McDowell for discussions.