Thursday 28 December 2017

Effects of December 26 Russian TOPOL RS-12M ICBM test also seen from the Netherlands

Image (c) Bussloo Public Observatory/Mark-Jaap ten Hove
click to enlarge
On 26 December 2017, Russia's Strategic Missile Force conducted a flight test with a TOPOL RS-12M ICBM from Kapustin-Yar in Astrakhan. The test was "aimed at testing perspective armament for intercontinental ballistic missiles".

The test resulted in a sky phenomena that was photographed from East and Central Europe, and, as it turns out, even NW Europe. A luminous bubble-cloud like phenomena appeared in the eastern sky as seen from Europe. There is some incredible imagery from Austria, as well as other locations.

I sent out an alert to the operators of the Dutch photographic all-sky meteor camera network to see if perhaps they captured something. Most stations were clouded out, but the station at the Bussloo Public Observatory in the east of the Netherlands did capture the event, amidst clouds!

Above is a part of the all-sky image: the phenomena is the ghostly neon-blue glow due east, behind the clouds. Below it a part of the same image in more detail:

Image (c) Bussloo Public Observatory/Mark-Jaap ten Hove
click to enlarge
Bussloo is at 6.12 E, 52.20 N. It is 2800 km distant from Kapustin-Yar, which is at 82 degrees azimuth as seen from Bussloo, so almost due East.

The cloud is exhaust from the missile at (very) high altitude in space, illuminated by the sun.

In the image, taken at 03:44 UT (December 26), the top of the blue cloud is at an altitude of ~30 degrees (stars from Corona borealis are visible in the blue cloud: the bright star somewhat right of the center in the second image is Arcturus).

Assuming the cloud is right above Kapustin-Yar, this would place the top of the cloud at an altitude of ~3300 km. If it is closer in range (e.g. when expanding and/or drifting westwards), it is lower.

(I thank Bussloo Public Observatory (Mark-Jaap ten Hove) for their kind permission to publish their photographs and all the Dutch all-sky meteor camera operators for checking their imagery)

Tuesday 19 December 2017

[UPDATED] Where to hide your nuclear missile submarine? (but be quick)

(Updated 20 Dec 2017 23:25 UT with a new plot that includes DSP)

Say, you are the leader of a nefarious country that is in posession of submarines equiped with long range nuclear missiles. You want to launch a stealth missile attack codenamed "Operation Orange Squeeze" on a northern hemisphere Super Power.

Where would you direct your submarine, and where would you best fire you missiles, from the perspective of an as-late-as-possible space-based detection of your missile launches?

The answer came to me today when, after a question by someone (in the context of a war crime investigation), I looked into the current global coverage of the Space Based Infra Red System (SBIRS), the US system of Early Warning satellites that looks for missile launches:

click map to enlarge

The red areas in the map above have an almost continuous coverage by SBIRS satellites (and often by multiple SBIRS satellites at the same time). The dark blue and black areas in the map by contrast have only a few minutes of SBIRS coverage each day, or even none at all.

As you can see, there is a clear gap in coverage in the southeastern Pacific, with lowest coverage in the area near the Galapagos islands. That is where I would park my nuclear missile submarine.

You might have to be quick to pull off your nefarious plan though. A new SBIRS satellite, the fourth satellite in the geostationary component, will launch in January. It wouldn't surprise me if it stops the gap, once operational.

Of course, this map is in fact somewhat deceptive anyway. It only shows the coverage by SBIRS. But there is also the legacy early warning satellite system called DSP (Defense Support System), which still has active satellites, and which is not taken into account here [UPDATE: but see the plot at the end of this post!]. It is less sensitive than SBIRS, but likely will detect your ICBM SLBM launch.

Back to SBIRS. SBIRS is made up of two components, each currently consisting of three satellites (so six in total): three geosynchronous SBIRS-GEO satellites at geostationary altitude, and three SBIRS-HEO satellites (TRUMPET-FO SIGINT satellites with a piggy-back SBIRS package) in 64-degree inclined Highly Elliptical Orbits with two revolutions a day.

click map to enlarge

The map above shows the coverage of the three geosynchronous SBIRS satellites (a fourth will be launched in January). Eurasia, Africa and the western Pacific Ocean has a continuous coverage by these satellites, with central Asia, Pakistan and India (the latter two known nuclear powers) particularly well covered.

The SBIRS-HEO coverage is more variable and depends on the date and time of day, but the system is designed such that at least one of the HEO satellites will have much of the Northern hemisphere in view at any time. Here are a few examples, for various times of the day: note how coverage of the Northern hemisphere is near-continuous (the HEO component also particularly covers the Arctic region well, which is at the edge of the GEO component's coverage).

click maps to enlarge
A SBIRS satellite typically has two modes: there is the scanning mode, which scans the whole visible hemisphere of the earth (as seen from the satellite) for infra-red heat signatures in less than 10 seconds. And there is the staring mode, a more sensitive sensor which can be used to observe a specific region or just detected infra-red event.

In the case of a missile launch, the sensors pick up the heat signal of the missile engine. Because of the large degree of worldwide coverage which the system now provides, an undetected stealth launch of a nuclear missile has become almost impossible.

SBIRS is probably an important source of  Early Warning capacity and information on the recent North Korean missile tests.

UPDATE 20 Dec 2017  23:25 UT:

I now also included the four DSP satellites that are still operational according to the database of the Union of Concerned Scientists. That leads to the following map:

click map to enlarge
As you can see, the gap has become smaller, but a gap is still there. Red October might be lurking in front of the South American west coast.

Wednesday 13 December 2017

Objects from the Ariane VA240 launch (Galileo 19, 20, 21, 22) observed from the Netherlands [UPDATED]

image 18:53 ~ 18:56 UT. Photograph (c) Klaas Jobse, Astronomy Project Oostkapelle
click to enlarge

On 12 December 2017 at 18:36:07 UT, an  Arianespace Ariane 5 ES rocket launched four Galileo navigation satellites into space from Kourou, French Guyana, for the European Space Agency (ESA).

Twenty minutes later, amateur astronomer Klaas Jobse (Astronomy Project Oostkapelle) in the village of Oostkapelle on the coast of the Netherlands imaged a phenomena in the sky (photograph above and photographs below). The imagery appears to show the tumbling Ariane EPC (Cryogenic Main Stage) and what appears to be a fuel dump cloud, about 10 minutes after separation of the EPC from the upper stage.

In one of the all sky images, a second trail is visible too (see detail image of all sky image below): this might be the EPS Upper Stage with the satellites, around the moment it shuts down and starts its coasting phase.

All Sky image. (c) Klaas Jobse, Astronomy Project Oostkapelle
click to enlarge
detail of the previous image.
(c) Klaas Jobse, Astronomy Project Oostkapelle
click to enlarge
All Sky image. (c) Klaas Jobse, Astronomy Project Oostkapelle
click to enlarge

detail of the previous image.
(c) Klaas Jobse, Astronomy Project Oostkapelle
click to enlargee
The flashing behaviour of the main trail (the suspected spent Cryogenic Main Stage) is probably due to tumbling after separation from the upper stage. On the first image (the one at the top of this post), which is a 30 seconds exposure, it is flashing 9 times, or about once every 3.3 seconds.

The images were captured by the automated routine meteor fireball patrol camera's of Astronomy Project Oostkapelle, which make continuous photographs of the night sky every clear night.

This is the approximate trajectory of the launch which I reconstructed from the Area Broadcast Warnings and information in the Arianespace presskit. It is approximate only:

click map to enlarge

Update 1, 13 Dec 2017, 23:00 UT:

The map above was based on ascend to the parking orbit of the Upper stage. Below is a 178 x 3440 km, 54.95 degree inclined reconstructed orbit for the EPC Cryogenic Main Stage, fitted to match measurements on the first image (the image in top of this post). Orbital position shown is for 18:56 UT:

click map to enlarge
 The rocket stage probably de-orbitted near the end of the first revolution, at about 20:40 UT.

 Update 2, 14 Dec 2017, 22:45 UT:

An engineer supporting the launch (@Dutchspace on Twitter) provided the info that the EPC Cryogenic Main Stage should have been in a 42 x 3340 km, 55.35 degree inclined orbit after separation and depressurization, with de-orbit at longitude 90.28 W. The elset and map below suit those constraints, and fit the observations from Oostkapelle closely:

click map to enlarge

Ariane EPC r/b                                           42 x 3340 km
1 70004U 17999C   17346.77516204 0.00000000  00000-0  00000+0 0    07
2 70004  55.3500 305.8931 2043588 353.6368 349.8559 11.97683367    04

rms 0.06

Update 3, 16 Dec 2017, 11:00 UT:

The phenomena was also imaged from Germany (see this article in Der Spiegel, which quotes me) and from Belgium.

(I thank Klaas Jobse for permission to publish his photographs. Photographs (c) Klaas Jobse, Astronomy Project Oostkapelle)

Tuesday 5 December 2017

The Curious Incident of the ICBM that Launched by Night

image: KCNA

North Korea conducted a test launch of a new ICBM, the Hwasong-15 (KN-22)  on 28 November 2017. The launch was at 18:17 UT from a field just north of Pyongsong, not far from Pyongyang. It was a "lofted" test, reaching an incredible 4475 km apogee before coming down near Japan, 950 km east of the launch location and some 250 km out of the Japanese coast. It is a beast of a mobile launched ICBM:

images: KCNA

After the launch, North Korea's KCNA press/propaganda agency published several pictures, showing Kim Jung Un directing the readying of the TEL with missile, and the launch.

Several of these images, both from the missile erection sequence before launch and the launch itself, show stars. As part of the verification of a geolocation attempt, Jeffrey Lewis (@armscontrolwonk on twitter) of the Middlebury Institute of International Studies, a well known wonk of the North Korean (and other) missile program, asked me to look into these starry backgrounds. Could I say something about image orientations?

I could, and it became very interesting. I initially looked at and measured these two pre-launch images (Jeffrey provided me with high-res versions of these: the ones shown here are the low-res versions from the KCNA website):

images: KCNA

These two images appear to be real (although, given what I will point out below, all images remain suspect, because they clearly aren't all real. With "real", I mean "untampered with" here). I used them to determine azimuth directions and the Local Sidereal Time (and from that UTC time) these images apparently were taken, by creating an astrometric grid over the image. In the image below, each dotted star is a reference star measured. The two images below it show the reconstructed azimuth range for each picture.

Of course, I now have reason to doubt the validity of this whole exercise. Because (hold on):

The real fun started when, yesterday evening, I started to look at the pictures of the actual launch moment. The fact that some of these show stars in itself is already something, as these images necessitate short exposures (unlike the pre-launch images above, which are long duration exposures), so you do not expect stars. But the real fun came when I looked at these stars visible. There, things clearly were not right!

Take these two images, which I have put next to each other for comparison:

Image: KCNA

The shape of the exhaust cloud and exhaust flame (and the number decal, extremities and paint job on the missile) clearly indicate they were taken from the same viewpoint, probably within a fraction of a second of each other. But take a look at the stars in the background: these then should show the same sky area, right?

But they don't!

One shows Orion, which is south-southeastwest. The other shows Andromeda with the Andromeda galaxy (this is a bit more clear in a higher resolution version I have), which is northwest. So these two images from the same viewpoint, show dramatically opposite sky areas.

Below is another example, doing basically the opposite. The mirror character of these two images, from the exhaust shape plume, exhaust flame shape, and the lack of number decal on the missile in one of the images, indicates they were taken from opposite viewing points. So the sky should show opposite sky areas on each of these, right?

images: KCNA
(NOTE: earlier version of image replaced with version correcting error in labelling)

Again, they don't.

The top one shows Orion (but with Betelgeuze missing). The bottom one shows Canis major (but with Sirius missing). Orion and Canis Major are very close to each other, south-southwest at the time of launch. The images should show opposing sky areas, but don't.

So clearly, the starry sky background was added to the imagery and is not original.

So why should North Korea have done this?

The most likely reason is simply that they did it for aesthetics. An ICBM soaring into the stars makes for good propaganda images. They apparently just didn't care enough to do it correctly.

Aesthetics seem to be important in North Korean propaganda pictures. They frequently photoshop the ears of Kim Jung Un in pictures, for example.

Or maybe they wanted to play a prank on analysts as well: they know these images will be analyzed by the west. Fooling around with clues as to the orientation of images makes it harder to glean information from them on 3-dimensional missile shape, and launch site geolocation.

To be clear (because some hare-brained individuals on social media seemed to think that was implicated, even though it nowhere is): nobody disputes that the launch was real.

It was, and it shows that North Korea now has an ICBM that can reach the whole US mainland. It can even reach my country, the Netherlands (although we are not a very likely target, I must ad):

But at least some of the launch images have been clearly doctored, and show elements that were added later. This is, of course, something we have seen earlier with North Korean propaganda images (some examples are given in the CNN article linked below).

End note: I still think the pre-launch imagery showing the TEL with missile being erected in the field is unaltered. So maybe my azimuth and timing determinations from these is are valid. But I cannot proof it, and of course now all the images must be considered suspect.

They do tally with some other evidence though, including this still I extracted from the KCNA released video, which briefly offers a glimpse of the moon, low in the west-southwest. If the video isn't doctored as well (!), this should be around 16:00-16:15 UT, some two hours before launch:

Still taken from KCNA video: moon indicated
If the video was not altered, then together with earlier images showing the missile on the TEL leaving the plant, this orientation means that any of the launch pictures showing the number decal on the missile should actually be looking Northeast to East.

My findings on the doctoring of the launch imagery featured in this CNN article from 5 December 2017 by Joshua Berlinger:  North Korea missile: Inconsistencies spotted in Hwasong-15 images

"Yay! We fooled those imperialistic coward dogs!" (image: KCNA)

Sunday 19 November 2017

Introducing TLE from Proxy

A simple way to estimate orbital elements for an upcoming launch, is to use elements from a previous, similar launch as a proxy.

For example, for a newly to be launched SpaceX DRAGON cargo spacecraft to the ISS launching from Cape Canaveral pad 39A, you can use a previous DRAGON launch from Cape Canaveral and then modify the elements to the new launch date and launch time. The method is described here by Ted Molczan in a Seesat-L mailinglist post from June 2002.

Basically, the method takes the elset from the previous launch and adjusts the epoch and RAAN values (all else being kept equal) based on the time difference between the original launch and the new launch.

To aid in this and make it as simple as a few buttonclicks, I have written TLE from Proxy. The program runs under the Windows .NET framework, and can be downloaded on my website.

Using the program is very simple, involving these five simple steps:

  1.  Obtain a TLE for a previous similar launch from Space-Track;
  2.  Paste line 1 and line 2 of this elset into the input box;
  3.  Fill in the date and time (in UT) of that launch;
  4.  Fill in the date and time (UT) of the new launch;
  5.  Press the button.

A new TLE will now be generated.

Note that in order for this to work, the launch must be from the same launch site, towards the same launch azimuth, and with a same launch-to-destination scenario.

Friday 17 November 2017

[UPDATED] Tomorrow's SpaceX Zuma launch

click map to enlarge

If nothing interferes (the launch has been postponed twice already), SpaceX will launch the classified Zuma satellite from Cape Canaveral Pad 39A in the early hours (UT) of  November 18.

Zuma  was originally scheduled for November 16, but was delayed a day to November 17, and then yet another day to November 18.

The published Maritime Area Warnings give a window from 00:55 to 03:37 UT for the launch. From the Area Warnings, the de-orbit of the Falcon 9 Upper stage happens some 2 hours after launch over the southern Indian Ocean, during the 2nd orbital revolution.

The launch and Upper stage de-orbit hazard zones (I plotted them in red on the map above) strongly suggest a launch into a 50-degree inclined, ~400 km orbital altitude Low Earth Orbit.

The map above plots the trajectory for the first ~1.5 revolutions in such an orbit. As can be seen in the map, such an orbit lines up well with the direction of the launch hazard zones, and with the Falcon 9 upper stage de-orbit hazard zone in the Indian Ocean. The fact that the first stage will return to the Cape for a landing argues for a launch into Low Earth Orbit too.

If a ~50-degree inclined, ~400 km altitude orbit sounds familiar to you: that is because this orbit would be very similar to that of the enigmatic classified satellite USA 276 which was launched - also by SpaceX - in May 2017. This is the one that made all those peculiar close approaches to the ISS in June (see some previous posts from June and my Space Review article here). Perhaps, but this is pure speculation based on suspected potential orbital similarities only, Zuma is up for a similar mission.

It is very interesting that Zuma seems to have been contracted via a similar procedure as USA 276, and that like for USA 276, it has not been made public which Agency will operate the Zuma satellite. So there appear to be similarities from that aspect as well.

It will therefore be interesting to see how the orbit of Zuma, once launched, compares to that of USA 276 and the ISS. The orbital plane of the ISS will be overhead for Cape Canaveral near 2:38 UT on the 18th, so a launch exactly into the ISS orbital plane is possible - and will stay possible for several days to come in case the launch is postponed again (the moment of the ISS orbital plane passing over the Zuma launch site happens ~24 minutes earlier each day).

On the 18th, the orbital plane of USA 276 will be overhead for Cape Canaveral some 10 minutes before the launch window opens. With the newest delay, a launch exactly into the orbital plane of USA 276 is therefore no longer feasible.

But by launching directly at the opening of the launch window on the 18th, the orbits of Zuma and USA 276 would nevertheless still be quite close (launch at 1:00 UT would result in a difference in RAAN of 3 degrees), and differential rates of precession of the RAAN might still slowly drift the two orbits towards each other over the next weeks and months, depending on what the actual orbital altitude and inclination Zuma ends up in would be.

Therefore a launch exactly into the orbital plane of either USA 276 or the ISS, strictly speaking is not necessary to engineer close approaches (indeed, USA 276 itself was not launched exactly into the ISS orbital plane in May).

So it might be worth monitoring Zuma and its behaviour in relation to both USA 276 and the ISS in the weeks after launch. Still, it is also very well possible that Zuma has nothing to do with both spacecraft whatsoever.

UPDATE 1  17 Nov 2017, 13:00 UT:

The  maps below show a comparison of the hazard zones (from Maritime Area Warnings) for the launch of USA 276 in May 2017, and for Zuma.

click maps to enlarge

The USA 276 de-orbit area is shifted more West-wards, because the Falcon 9 upper stage de-orbit from that launch was de-orbitted one orbital revolution later than apparently planned for Zuma. The small difference in size might point to slightly different orbital altitudes for the upper stage (e.g.due to  a somewhat different collision avoidance manoeuvre after payload separation)

UPDATE 2  17 Nov 2017, 13:00 UT:

SpaceX has released a statement that, while not taking a launch tonight off the table, might indicate a further prolonged delay.


These are the Area Warnings published for the launch. They are graphically depicted in the map in the top of this post and the two maps above.

NAVAREA IV 1067/17

160055Z TO 160337Z NOV, ALTERNATE 
170055Z TO 170337Z NOV IN AREAS BOUND BY: 
A. 28-38N 080-43W, 29-12N 080-06W, 
30-04N 079-00W, 29-56N 078-52W, 
28-41N 080-10W, 28-26N 080-21W, 
28-22N 080-38W. 
B. 30-04N 079-00W, 30-52N 
078-17W, 31-32N 077-25W, 
31-54N 076-49W, 31-49N 076-45W, 
31-36N 076-57W, 30-44N 077-53W, 
29-56N 078-52W. 
2. CANCEL THIS MSG 170437Z NOV 17.// 

Authority: EASTERN RANGE 072156Z NOV 17. 

Date: 110428Z NOV 17 
Cancel: 17043700 Nov 17 

HYDROPAC 3895/17 

DNC 03, DNC 04. 
160300Z TO 160637Z NOV, ALTERNATE 
170300Z TO 170637Z NOV IN AREA BOUND BY 
30-27S 064-51E, 30-44S 067-03E, 
38-10S 082-43E, 47-22S 108-39E, 
50-30S 124-39E, 51-55S 126-03E, 
53-32S 125-05E, 54-24S 116-01E, 
53-34S 101-27E, 47-46S 082-05E, 
39-58S 069-31E, 31-56S 063-23E. 
2. CANCEL THIS MSG 170737Z NOV 17.// 

Authority: EASTERN RANGE 072155Z NOV 17. 
Date: 110407Z NOV 17 
Cancel: 17073700 Nov 17

Friday 3 November 2017

Introducing IOD Entry: software to aid observers in creating IOD formatted observational data [UPDATED]

International amateur satellite observers (well: apart from the British, who use their own format) generally use the IOD format to communicate positional measurements on satellites. The IOD format however can be cumbersome and error-prone to manually write.

In the old days, there was a neat little DOS program called ObsEntry to help you turn your data into IOD format. Unfortunately, this no longer works on newer Windows machines.

Time for something new to replace it: so I present to you IOD Entry 1.0!

IOD Entry 1.0 is software that runs under the Windows .NET framework, which is a standard component of Windows 7 and later (otherwise, the .NET framework can be downloaded here). I wrote it in Visual Basic using Microsoft Visual Studio 2017, as part of self-teaching me to code .NET windows applications in Visual Basic.

The program and how to work with it is described in detail in this mailinglist post. The program can be downloaded as a .zip file through my astronomy software page at It is (of course) freeware.

UPDATE: IOD Entry version 1.1 has now been released. It allows to choose the format of both the Right Ascencion and Declination entries. For the RA, the choice is between HH MM SS.s, or decimal degrees. For the declination, the choice is between degrees, arcminutes and arcseconds, or decimal degrees.

Version 1.1 can be downloaded at the same link above.

Wednesday 4 October 2017

The Space Age turns 60

click to enlarge
Today at 19:28:24 UT, it is exactly 60 years ago that Sputnik 1, the first artificial satellite of the Earth, was launched from Tyuratam (Baikonur) in the Soviet Union. Thus, the Space Age was born.

Sputnik 1 would stay in orbit for  four months and then re-entered into the atmosphere. The image above shows the very first two orbits (and is based on a TLE from the website of Jonathan McDowell. Strictly speaking, this TLE is for the upper stage of the rocket, but during the first few orbits the orbits of both objects were very similar).

Monday 2 October 2017

The North Korean Hwasong-12 test of 14 September: georeferencing Kim Jong Un's map

(This post has been a while in the making. Due to various reasons, including the 21 Sept fireball, I did not come to write it up on this blog until now. The same analysis however was earlier presented as a Twitter-thread, on 23 September)

"I love the smell of UDMH in the morning..." (photo: KCNA)

Over the past months, I have spent a number of posts on North Korea's recent increasingly bold missile tests. The latest of these tests happened on September 14 (local September 15 in North Korea). At 21:57 UT that day, North Korea launched a Hwasong-12 IRBM from Pyongyang Sunan airfield towards the east-northeast. It crossed over Japan (causing air-raid alarms to go off) with, according to western military sources, a range of ~3700 km and apogee at 770 km, before impacting in the Pacific Ocean. The test was the second one to launch the Hwasong in a 'regular' rather than 'lofted' trajectory, over Japan.

I was abroad at the time of the test,  meaning it was several days before I could look at this test and start an analysis. Some results were earlier presented on 23 September as a Twitter-thread.

photo: KCNA

As part of the propaganda photographs published by KCNA following the test, there was (just like after the test of 29 August) a picture of Kim Jong Un sitting behind a desk, with a map in front of him. As was the case for August 29, the map shows a missile trajectory, presumably the trajectory aimed for in this test:

photo: KCNA

I obtained a high resolution version of this photograph for analysis with the much appreciated help of Ankit Panda. First, I roughly squared this image using the skew-tools in Photoshop:

Next, I georeferenced this image against an actual map using QGIS. The resulting map is the one below (the map projection I have used is a Lambert azimuthal equal area projection centered on Sunan. The grid is WGS84). :

click map to enlarge

The result of this georefencing is that the drawn trajectory starting at Sunan ends at approximately 39.60 N, 168.05 E. The range from Sunan to this impact location is 3615 km.

Note that I have added, in yellow, country outlines to the map to show the validity of the georeferencing. I also added a few annotations. I have added an STK-modelled ballistic trajectory to the map as a dashed red line: it is highly similar to the original trajectory line drawn on the map, as you can see, with apogee position corresponding to what appears to be a text in red on the map: what was depicted on Kim Jong Un's map hence appears to be a real ballistic trajectory.

The resulting range of 3615 km is close enough to the range reported by Western military sources (about 3700 km) to conclude that the 14 September test went much as intended.

This is a difference with the 29 August test. In that case, the map showed a ~3300 km range while western military sources said the actual range flown was ~2700 km: it also flew more north than the trajectory that was depicted on the 29 August map. See my earlier blog post here. The match for the 14 September test might indicate that the 29 August test perhaps did not go as intended.

The map below shows both trajectories: that of 29 August as depicted on Kim Jong Un's map (i.e. not the actually flown trajectory!), and that of 14 September as depicted on Kim Jong Un's map:

click map to enlarge (map by author)

It is interesting to look at the range distances for both tests. The range distances of 3316 km and 3615 km ring a bell. The distance from Pyongyang Sunan (the launch location) to Henderson AFB on Guam is ~3415 km. The August 29 map trajectory falls almost exactly 100 km short of that range, while the September 14 trajectory almost exactly 200 km overshoots this range.

I am going back-and-forth on whether this is significant or not. I tend to think that all these kind of map images released are intentional propaganda meant to convey a message: the map is meant to be analysed and "read" by the West.

As an illustration of how it potentially could be read: would we change the launch directions so that they would be towards Guam, then this (the two black crosses) would be the result in terms of the pattern of impact locations relative to Guam:

Remember that North Korea has "threathened" to conduct a quadruple demonstration with four missiles impacting in international waters in an 'envelope' around Guam, if the Trump administration does not stop B1 bomber demonstration flights from Guam. Do we see some kind of test mock enactment for this here? Is the message: "We are already practising for this, imperialist barking dottard dog!".

It would become very interesting if North Korea were to launche two other missiles the coming month, and the pattern where they (were implied to) land relative to the earlier two tests might be very interesting.

photo: KCNA
(I thank Ankit Panda for his help with obtaining a high resolution version of the photograph with Kim Jong Un and the map)

Tuesday 26 September 2017

OT: The brilliant fireball over the Netherlands of 21 September 2017, 19:00 UT, a piece of comet Encke

The fireball as photographed from Ermelo, the Netherlands. Image (c) Koen Miskotte

In the evening of 21 September 2017 at 21:00:10 CEST (19:00:10 UT), a brilliant fireball, as bright as the first quarter moon, appeared over the Netherlands. It was widely seen and reported and garnered quite some social media and press attention (e.g. here). The next day I was live in a Dutch TV program to talk about it.

The fireball was captured by six all-sky camera stations of the Dutch-Belgian all-sky meteor camera network operated by amateurs of the Dutch Meteor Society and KNVWS Meteor Section: stations Ermelo, Oostkapelle, Borne, Utrecht, Twisk and Wilderen, operated by respectively Koen Miskotte, Klaas Jobse, Peter van Leuteren, Felix Bettonvil, Marco Verstraaten and Jean-Marie Biets.

The image in the top of this post shows the photograph taken by the all-sky camera in Ermelo (courtesy Koen Miskotte), where the fireball appeared almost right overhead. The image below was taken by the all-sky camera in Utrecht (courtesy Felix Bettonvil), showing it slightly lower in the sky (click the images to enlarge).

The fireball as photographed from Utrecht, the Netherlands. Image (c) Felix Bettonvil

In the photographs above, the "dashed" appearance of the fireball trail is caused by an LCD shutter between the lens and the camera CCD, which briefly interupts the image at a set interval. For Ermelo this was 14 interuptions per second, for Utrecht 10 interuptions per second.

Knowing the shutter frequency you get the duration of the fireball by counting the number of shutter breaks in the trail: in the case of this fireball, it lasted over 5.3 seconds. Together with triangulation information on the path of the trail in the atmosphere, it gives you the speed of the fireball in km/s, which is necessary to calculate the orbit in the solar system. It also provides you with information about the deceleration of the meteoroid in the atmosphere. In this case, it entered the atmosphere with a speed of 31 km/s and by the time it had completely burned up at 53 km altitude, the speed had decelerated to 23 km/s.

The fireball fragmented into pieces quite early during its atmospheric entry. Some of these fragmentation events can be seen as brief brightenings (flares) in the images.

Triangulation of the six all-sky images yields the following atmospheric trajectory:

Atmospheric trajectory of the fireball, calculated by the author. Camera stations in yellow.

The  fireball moved almost due east-west. It started over Deventer, crossed over southern Amsterdam and Schiphol airport, and ended over sea. The end altitude at 53 km and end speed of 23 km/s indicate that nothing was left of the original meteoroid by the time the fireball extinguished: no meteorites reached earth surface, it completely ablated away.

The apparent radiant of the fireball was located low in the sky, at 16 degrees elevation and almost due east. The grazing entry into the atmosphere resulted in a long trajectory length of over 150 km.

The geocentric radiant of the fireball is located on the Pegasus-Pisces border, just north of the ecliptic. The radiant and speed, and the resulting orbit in the solar system, show that this was an early member of the northern branch of the Taurid stream complex, a meteor stream complex associated with comet P/Encke. It is active from September to December with a  peak in activity in November. The stream is broken up in several substreams, and the early Northern Taurids from September are sometimes called Northern delta Piscids, one of these substreams in the Taurid complex.

The radiant position and heliocentric orbit for this fireball are shown below.

apparent (observed) and geocentric radiant of the fireball

calculated heliocentric orbit of the meteoroid

Acknowledgement: I thank the photographers (Koen Miskotte, Klaas Jobse, Peter van Leuteren, Felix Bettonvil, Marco Verstraaten and Jean-Marie Biets) for providing their imagery for this analysis.