Thursday, November 12, 2015

Small unusual artificial object WT1190F will impact in a few hours [UPDATED with imagery of actual impact]

click image to enlarge

(for an update with imagery of the actual impact of this object from a research plane, see bottom of post)

The animated GIF above was made from images which I took just a few hours ago with the 0.61-m Cassegrain telescope of MPC G68 Sierra Stars Observatory in Markleeville, California.

The moving object is WT1190F, discovered on October 3 this year by the Catalina Sky Survey. This small peculiar object will impact in a few hours from now (near 6:18 UT, Friday 13 November 2015) just south of Sri Lanka.

It is an unusual object that is not a Near Earth Asteroid but almost certainly a small (1-2 meter) artificial object. It is moving in the Earth-Moon system (i.e. in a very elliptic orbit around earth) and its orbit is under influence of Solar Radiation Pressure, which shows that it is very light weight for its size. This fact, and the geocentric rather than Heliocentric orbit with apogee at twice the distance to the Moon, suggests it is some piece of hardware from a past Lunar mission.

image credit: Bill Gray, Project Pluto

It is not clear from which Lunar mission this object is a relic: it could be from one of the American missions, but also Russian or Chinese. The object in question turns out to have been sporadically observed since 2009, as it is probably the same object earlier designated 9U01FF6 in 2009 and UDA34A3 and UW8551D in 2013.

Shortly after its (re-) discovery on October 3, Bill Gray noted that the orbit yielded impact solutions on November 13 near 6:18 UT. The predicted impact point is over the Indian Ocean, just south of Sri Lanka. Bill Gray has put up a FAQ for this object with maps of the orbit and impact location here.

image credit: Bill Gray, project Pluto

As this is a small, 1-2 meter sized and lightweight object, the impact is harmless. It will burn up in the atmosphere and likely nothing will reach the water surface. It provides scientists with a good opportunity though to observe what happens during a small asteroid impact, as the speed and entry angle of this object is quite similar (see also the project page here).

The astrometry obtained from my images makes, along with data by many other observers, a modest contribution to  establishing the impact point and time as good as possible.

1st UPDATE, 13 Nov 2015, 09 UT:  WT1190F is now toast for a few hours. South Sri Lanka seems to have been clouded out, but there are reports on Twitter of sonic booms from the re-entry heard in Sri Lanka. 

In response to some of the comments, I want to point out that WT1190F is/was not the only artificial object in a trans-Lunar orbit which we were/are tracking. Here you can find an earlier post (out of several) on tracking 2010-050B and 2013-070B, two rocket boosters in trans-Lunar orbits from the Chinese Chang'e 2 and Chang'e 3 Lunar missions.

2nd UPDATE,  13 Nov 2015, 13 UT:  The first imagery (below, three stills and the video) has just appeared of the actual impact near Sri Lanka, shot from a research aircraft organized by IAC / UAE Space Agency / NASA / ESA:

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Wednesday, November 04, 2015

Flight MH17, satellite data and yesterday's hearing of Dutch Parliament with the Dutch Safety Board

Yesterday I posted (in the context of what appears to refer to SBIRS detections of the recent aircraft crash in the Sinai) on lingering questions with regard to potential US military satellite data on the shootdown of flight MH17 over east Ukraine in July 2014. I blogged about this a year ago too.

Yesterdays recapitulation was timely in many ways, as yesterday afternoon saw a special hearing between Dutch Parliament members and the Dutch Safety Board (DSB), the agency which investigated the tragedy. The latter published its report on their finding in October, leading to yesterday's special Parliament hearing. Several Dutch MP's questioned the DSB representatives about what they perceive as ambiguities and missing information in the report. Among them, potential satellite data.

Dutch MP Pieter Omtzigt especially focussed  on potential US military satellite data (including SBIRS data) in his questions, partially basing his information on this very blog. For those of you who understand Dutch, the most relevant of his questions pertaining to satellite data start at 10:30 in the video snippet at this link.

The answers by the DSB representatives were interesting: they seem to indicate that there are indeed satellite data, although it was not entirely clear what satellite data they were talking about: SBIRS IR detections of the missile launch and ascend trajectory, or KH-11 optical imagery of the relevant parts of the Ukraine before and after the shootdown. Their answers also seem to indicate that DSB members were given access to these data, but cannot publicly report on it because "State Secret"...

For truth finding, these data are extremely important. They are likely much less ambiguous than the reconstructions from the missile impact damage to the aircraft on which the DSB report is basing the reconstructed launch location of the missile. As a Dutch citizen, the country that lost 198 citizens in the tragedy, I sincerely hope that the US government does the right thing and will eventually release enough of these data to confirm where the missile that killed so many innocent men, women and children was launched from. That would be the only ethical and humane thing to do. In a democracy, especially where truth finding is concerned, some things are more important than upholding secrecy, certainly in connection to such a terrible tragedy as this involving the killing of such a large number of citizens of a long time US ally.

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Tuesday, November 03, 2015

Satellite observations and the Russian Metrojet crash in the Sinai [updated]

[updated 3 Nov 2015 14:00 UT]

On 31 October 2015 near 4:13 UTC, Kogalymavia Flight 9268, a Russian commercial flight by airliner Metrojet, crashed in the Egyptian Sinai desert, tragically killing all 224 people on board.

NBC News now reports that according to a US "senior defense official", around the time of this tragedy, a heat signal has been detected over the Sinai by "an American infrared satellite". According to NBC News, the heat signal detection points to an explosion (either mid-air or when the aircraft hit the ground), and the quoted official reportedly said that there is "no indication" that a surface-to-air missile hit the aircraft.

The satellite system in question which detected the heat signal is most likely the classified SBIRS (Space-Based InfraRed System), which I discussed before in the context of the shootdown of Malaysian Airlines flight MH17 over the eastern Ukraine a year ago.

It is one of two US military systems (there is the older DSP now being replaced by SBIRS) meant for the early detection of (intercontinental) missile launches. These satellites look for the infrared (heat) signature of such launches. For more details see my earlier post on MH17, and this detailed information sheet by US Defense itself available on the web.

After reading NBC's claim of a satellite detection of this latest aircraft tragedy, I checked which of the SBIRS satellites would have had coverage of the area in question at 31 October 2015, 4:13 UT.

click image to enlarge

Two SBIRS satellites had excellent coverage: the geostationary SBIRS GEO 2 (2013-011A) satellite at longitude 20 E, and the piggyback SBIRS package on the TRUMPET-FO satellite USA 184 (2006-027A) in a Highly Elliptical Orbit (HEO).

click images to enlarge

The apparent quick confirmation of a SBIRS detection of the Sinai crash reported by NBC News not only shows the capabilities of the SBIRS system, but also begs the question why such information is still lacking with regard to the shootdown of MH17 over the Ukraine a year ago.

In my country, which lost 192 citizens in that tragedy, the downing of MH17 and the question of who is responsible for it are still a hot topic, newly fueled by the recent release of the report by the Dutch Safety Board which shows it was a BUK system that downed the aircraft.

There are tantalizing clues that SBIRS did detect the 2014 shootdown over the Ukraine: the day after the MH17 tragedy unfolded, a "senior US official" reportedly told CNN that a US military system "saw a heat signature at the time the airliner was hit".

This is a very similar statement as the one now reported in connection to the Sinai crash. At the time, I showed that three SBIRS satellites (the same two as indicated above, plus SBIRS GEO 1) had coverage of the Ukraine crash location.

Following that CNN report, this apparent infrared detection has gone into oblivion: there is no mention of it for example in the report of the Dutch Safety Board: the reconstruction of the area where the missile could have been launched is completely based on modelling from the damage pattern to the aircraft's cockpit.

I find it hard to believe, certainly given the anonymous "senior US official" quote to CNN directly after the disaster, that there are no SBIRS detections of the MH17 shootdown.

NATO interest in the area was high at that time, after all this was a quickly escalating conflict right at the border of NATO's and the European Union's influence sphere. The general perception was (and is) that Russia, increasingly seen as the new/old enemy of (east-) European freedom, is trying to expand it's own influence sphere into Europe, and is muscle-flexing towards the east European NATO members. Missiles should have been a natural point of interest to NATO, as a Ukrainian military aircraft had been shot down at high altitude in the days before the disaster with what must have been a state-of-the-art Surface-to-Air system, something which should be of concern to NATO, especially given a US military strategy that heavily relies on Air Supremacy. To me it seems that it would be very odd if US military systems like SBIRS were not watching the area.

UPDATE 3 Nov 2015, 14:00-14:30 UT:

In a Twitter conversation, Rainer Kresken rightfully points at  the weather conditions over the relevant part of the Ukraine during the MH17 tragedy. Cloud cover is detrimental to IR detections. But a SAM would still be detectable once it had cleared the cloud cover. According to the report of the Dutch Safety Board, the cloudbase present in the general area around the time of the crash was scattered and between 1000 and 5000 feet (300 meter to 1.5 km) with occasional peaks of the top of the cloud deck to FL350 (350 000 35 000 feet, 10.7 km). These latter were localized thunderstorms. Airfields in the vicinity report scattered clouds at 3300 feet (1 km) and a broken cloud cover at higher altitude, 10000 to 20000 feet (3 to 6 km). This all suggests that a missile would have been visible once clearing 1 km altitude, unless it was cruising through a cumulus tower from a thunderstorm.
Most relevant to me is still that tantalizing CNN quote of a "senior US official" reporting a heat signal, suggesting that there was a SBIRS detection of the missile above the cloud cover.

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Friday, October 30, 2015

OT - on Dutch TV about the close approach of asteroid 2015 TB145 ("Spooky")

Yesterday evening (29 Oct 2015) I was a guest in the Live broadcast TV show "Z Today" by Dutch commercial broadcaster RTL Z.

Topic was the close approach of the 200-600 meter large asteroid  2015 TB145 (with the unofficial nickname "Spooky") which comes to within 1.25 Lunar Distances on 31 October 2015. The item is 8 minutes (and in Dutch, of course).

Embedding the video in this post won't work for some odd reason, but here is a link to it.

Monday, October 12, 2015

Chasing the new NOSS 3-7 pair (the NROL-55 payloads)

NOSS 3-7 (NROL-55) payloads on 2015 October 10, two days after launch
Click image to enlarge

On October 8th 2015, an Atlas V rocket launched the National Reconnaissance Office's NROL-55 mission from Vandenberg AFB. The mission consisted of two NRO payloads and a number of cubesats hitching a ride. The two NRO payloads (of which only one is acknowledged, the other being catalogued as 'debris', which it isn't) are a new NOSS pair, NOSS 3-7, which replaces the 10-year-old NOSS 3-3 duo (2005-004A and C).

NOSS (Naval Ocean Surveillance System) satellites operate in pairs, flying in close formation. They geolocate ships by radio interferometry observations of the ship's radio and radar signals.

Based on the launch direction and rocket used, as well as the few details published, we knew it would be a new NOSS duo, and from previous launches had an idea in what orbit they would be launched and what manoeuvering sequence would be used.

The first observations of the newly launched objects were made within a few hours after the launch, by several observers. About 1.5 hours after the launch, observers in Iran and Tibet witnessed a spectacular fuel vent by the Centaur rocket from the launch. Next a number of satellite trackers in our network observed the payloads and the Centaur rocket (e.g. here, here, and here).

I was clouded out on Oct 8. I could join in the chase and got my first look at the payloads only on the next evening on the 9th, but under poor conditions (very hazy) with the objects only marginally showing up on my imagery made with a 2.5/50 mm lens.

NOSS 3-7 (NROL-55) Centaur near Altair on 2015 October 10
Click image to enlarge

The next night, on the 10th, the sky was very clear, and I employed the 1.4/85mm lens rather than the 2.5/50mm lens. First, I imaged a pass of the Centaur rocket near 19:47 UT (image above). As is usual for the Centaur boosters from these launches, it was clearly variable in brightness due to tumbling. This can be clearly seen in the image below, a stack of five images:

NOSS 3-7 (NROL-55) Centaur, stack of 5 images showing brightness variation
Click image to enlarge

Next I observed the two payloads closely chasing each other near 19:55 UT. Like the previous evening, the leading object was clearly fainter than the following object (movement is from top to bottom in the image below, showing the two payloads crossing a part of Cassiopeia).

NOSS 3-7 (NROL-55) payloads on 2015 October 10, two days after launch
Click image to enlarge

NOSS pairs operate for about 10 years, each pair maintaining a close spatial proximity configuration of parallel orbits with one satellite just leading the other. After 10 years their mission is over and the pair loses their close spatial proximity. From previous patterns, Ted Molczan expects that the NOSS pair that is being replaced by this new launch (NOSS 3-3, 2005-004 A and C, launched in 2005) will end its mission and lose their close spatial proximity about 7-8 months from now, i.e. around April-May 2016.

click image to enlarge

The newly launched NOSS 3-7 duo is not yet at its operational orbit in its operational configuration. Based on past missions, they will continue to manoeuver the next few weeks until they reach their operational orbits (after which a check-out period will follow). This manoeuvering makes them interesting targets to follow the coming few weeks.

The image at the top of this post shows the pair of payloads (moving top to bottom through Cassiopeia in the image), with the leading object being slightly fainter than the trailing object. This is a pattern also seen with previous launches: once operational, both payloads will however be of similar brightness.

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Saturday, October 10, 2015

[UPDATED] Imaging North-Korea's Kwangmyŏngsŏng-3 (KMS 3-2) satellite

Kwangmyŏngsŏng-3 (KMS 3-2) passing Deneb, evening of 10 Oct 2015
click image to enlarge
UPDATE (11 Oct 2015):
I imaged Kwangmyŏngsŏng-3 again the next evening (image above), 10 Oct 2015 near 18:32 UT, when it passed the bright star Deneb (brightest star in image). This time I used the Zeiss Sonnar MC 2.8/180mm lens, which shows fainter objects but has an even smaller FOV. The trail is faint but shows up well (click the image to enlarge).

Kwangmyŏngsŏng-3 (KMS 3-2), evening of 9 Oct 2015
click image to enlarge

[original post before update:] Yesterday evening started clear. While my targets for that evening were the payloads of the NROL-55 launch from October 8 (more on that in a later post), I took the opportunity to image a pass of North-Korea's satellite Kwangmyŏngsŏng-3 (KMS 3-2) in the early part of the evening. The image above shows it, as a very faint trail.

Kwangmyŏngsŏng-3 (2012-072A) makes favourable passes in early autumn and in spring. In October it is making evening passes. Yesterday I had a very good illuminated pass near 20:50 local time (18:50 UT).

By coincidence my imaging of KMS 3-2 yesterday happened on the eve of the 70th anniversary of the Worker’s Party of Korea. There were rumours of a pending new N-Korean satellite launch, perhaps with a stronger rocket, on or near that date, although at least one assessment of satellite imagery by the 38 North blog, suggests the new launch platform at Sohae, which North-Korea has been building the past year, is far from ready yet.

KMS 3-2 is a difficult object to photograph, as it is very faint: it is a cube of only about 1.0 x 0.75 meter in size. It is also tumbling. This makes it a challenge: it is in a Low Earth Orbit and moving relatively fast, but a  lens which is fast enough to capture it during it's brief brightness peaks has a limited FOV. In practise, my f1.4/85mm lens can just show it during the brightest part of it's periodic brightness variability, but it is a gamble whether that happens in the FOV or not. So far I had managed to image it once before, a year ago.

Yesterday evening, I was lucky again: during a nice high late twilight pass with the the satellite culminating at an elevation of 60 degrees in the W-SW, it did reach peak brightness in the FOV of my lens, resulting in four images showing it. The best of these is shown above.

click image to enlarge

Kwangmyŏngsŏng-3 was launched three years ago, on 12 December 2012. It was the first successful launch by North-Korea, in the sense that the payload reached orbit. Whether the payload is operational (as PyongYang claimed), is another question. It's brightness behaviour shows it is tumbling, which is something an operational Earth Reconnaissance satellite should not do.

At the time, I did an analysis of the launch-window. It appeared to have been very carefully choosen to avoid coverage of the launch site (and specifically last-minute launch preparations) by Western reconnaissance satellites in the hour before the launch. Interestingly, North-Korea tried to find orbital elements for such Western reconnaissance satellites by looking on this very weblog.

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Tuesday, September 29, 2015

OT - the Lunar Eclipse of 28 September 2015 from Leiden

click image to enlarge

Leiden had clear skies during the night of September 27-28, which meant a good view of the total Lunar Eclipse in the early morning of September 28.

For me, this eclipse occurred mostly at rooftop level, with the moon sinking from 34 degrees elevation at first contact with the umbra, to 11 degrees elevation at last contact with the umbra. During mid-totality, at 2:47 UT (4:47 am local time), the moon was at 21 degrees elevation, just disappearing behind the rooftops for me.

After setting up my Celestron C6, I could use the telescope until about 2:40 UT, when the moon disappeared behind the rooftops. I then went to my girlfriend's appartment, which (from the 2nd floor) has a good view Westwards, and continued photography with simpler means during the second half of the eclipse.

click image to enlarge: it is worth it!  See text for details

There I shot a series of images with the Canon EOS 60D and the EF 2.5/50 mm Macro lens on a tripod. 14 of these images, shot in 5-minute intervals, where then stacked to create the image above, which shows the second half of the eclipse from 03:15 UT to 04:20 UT, i.e. from late totality until just before last contact with the umbra. The lens was set at F5, camera on 250 ISO, and exposure times were 4 seconds at the start of the series, and 0.5 seconds at the end. It shows that you don't need a telescope to get nice pictures.

Of course, a telescope does allow for very fine pictures. Below are some results from the first half of the eclipse, taken with my Canon EOS 60D through my Celestron C6 (15 cm F/10 Schmidt-Cassegrain with F6.3 focal reducer):

Moon in penumbra, 01:04 UT, just before first contact with umbra
(1/200 second, 100 ISO) click image to enlarge

Entry in umbra progressing (1/50 second, 100 ISO), 01:30 UT
click image to enlarge

Four minutes before totality (3.2 seconds, 200 ISO), 02:06 UT
click image to enlarge

Totality, 02:32 UT (10 seconds, 800 ISO). Note two stars near top lunar disc
click image to enlarge

This was a rather dark eclipse, to my estimate at the edge of L1/L2 on the Danjon Scale. The best moment for me was just before totality, when the moon sat just above the roof as a dark red-purple globe with a bright crescent on the lower edge: it looked a bit like Mars with a polar cap this way.

And by the way: NO! I refuse to go along with that "Super Blood Moon" nonsense. Puh-Lease!!!!

The "Blood Moon" denomer is actually of very questionable origin. It is not (contrary to what some people seem to think) an old folkloristic name for a Lunar eclipse, but is a denomer coined only a few years ago by two American Christian religious doomsday fanatics, who prophecied that the tetrad (series of four lunar eclipses each six months apart) starting with the eclipse of April 15, 2014 and ending with this eclipse of September 28, 2015, were a sign of the End of Times being near. They got their inspiration for this name from a sentence in the Bible, in the Book of Revelations.

Unfortunately, it seems everything in our modern society has to be expressed in ridiculous hyperbole nowadays. Ad to that media ignorant of the origin of the denomer "Blood Moon" with some religious crackpots, and you end up with horrible abominations like "Super Blood Moon" for what in essence was a nice and impressive, but in itself not particularly distinctive or rare Lunar eclipse...

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Friday, September 25, 2015

MUOS 4 at its 172 W check-out location

MiTEx 1 on 16 September 2015
(click image to enlarge)

On September 16, I was using the Warrumbungle 0.51-m telescope in Australia to track MiTEx. Indeed, MiTEx 1 (2006-024A) was imaged as a faint object close to the expected location (image above).

But about 5 degrees Northeast of MiTEx 1, I imaged another, very bright object (see image below) at approximately 172 W. It was too bright to be MiTEx 2 and didn't fit any known object. This UNID turned out to be the newly launched classified military COMSAT, MUOS 4 (2015-044A).

MUOS 4 on 16 September 2015
(click image to enlarge)

MUOS 4 was launched from Cape Canaveral with an Atlas V rocket two weeks earlier, on 2 September 2015. It is the fourth satellite in the Mobile User Objective System (MUOS) system of Geosynchronous narrowband communication satellites, the first of which was launched in 2012. This system of military COMSAT is to provide communication facilities to 'mobile users': i.e. military personel in non-fixed positions such as ships, aircraft, tanks and vehicles or on foot. It is a replacement for the aging UFO constellation of COMSAT.

The MUOS system is to consist of four operational satellites and one spare fifth satellite. According to a publication by Oeting et al. in the Johns Hopkins APL Technical Digest 30:2 of 2011, the operational satellites will be placed in slots at longitudes:

15.5 W
100 W
177 W
75 E

...while the spare satellite (MUOS 5, to be launched) will be placed at longitude 72 E. Compare this to the actual locations of the MUOS satellites according to our tracking:

MUOS constellation, from Oeting et al. 2011
(click image to enlarge)

Current locations of MUOS satellites,
based on amateur tracking:
MUOS 1   2012-09A       177 W  Pacific
MUOS 2   2013-036A      100 W  CONUS
MUOS 3   2015-002A     15.8 W  Atlantic

MUOS 4   2015-044A      172 W  (check-out)

(click map to enlarge)

The map and table above show the current locations of MUOS 1, 2 and 3 (from Mike McCant's INTTLES file). The positions agree well with the slots depicted in the mentioned publication.

(and yeah: if you think it is a tad silly that these orbits are 'classified' while the intended orbit slots have been published in a publicly available publication, you are of course right).

The yellow dots in the map are ground facilities related to the MUOS system. The MUOS constellation is designed such that each satellite has at least two Radio Acces Facilities (RAF) in range.

MUOS 4 imaged on 24 September 2015

My additional observations on September 24 (see image above) show that MUOS 4 is stationary at 172 W, as depicted in the map below. An approximate orbit for the satellite can be found here.

(click map to enlarge)

As MUOS 4 appears intended for an operational slot at longitude 75 E over the Indian Ocean (red dot in the map above), this means the current location at 172 W is not the intended operational longitude. Rather, it is a temporary initial check-out location. Once check-out is completed (and this might take several weeks), it will probably be moved to longitude 75 E.

(click images to enlarge)

This check-out position at 172 W has been used for the MUOS satellites before, according to Ted Molczan ( It is in range of three MUOS ground facilities: two Radio Acces Facilities (RAF) at Wahiawa in Hawaii and (although barely) Geraldton in Australia, and the primary Satellite Control Facility (SCF) in Pt. Mugu, California.

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Monday, September 21, 2015

The slow, changing tumble of the USA 144 (Misty 2) decoy

The USA 144 Decoy (1999-028C)
(click image to enlarge)

Yesterday evening I did some observations on the two evening KH-11 Keyholes (USA 186 and USA 245). Following that, I targeted the USA 144 decoy (1999-028C), an enigmatic object from the launch of the stealth satellite Misty 2 in 1999.

Three classified objects and one unclassified: the USA 144 Decoy, NOSS 3-4 A & C,
and an old rocket booster with CAMEO attached
(click image to enlarge)

At left in the image above is a double trail of the classified NOSS 3-4 duo (2007-027 A & C). In the middle is an old Delta 1 rocket booster (78-098B) with CAMEO on top, an earth magnetosphere experiment from 1978. At right, the shortest trail, is the enigmatic classified object we call the USA 144 Decoy.

I have written about this enigmatic object before. It is a bright object in a high 2665 x 3155 km orbit originating from the Misty 2 Stealth satellite launch in 1999.

(click image to enlarge)

From a study of its orbital behaviour, Ted Molczan found that the orbital decay of this object is notably influenced by Solar Radiation Pressure (SRP). This suggests an object that is very "light" relative to its size, i.e. an object with a large area-to-mass ratio. This does not fit a normal payload, so we suspect that this relatively bright object might have been a decoy to attract attention away from the real, stealth payload.

The USA 144 Decoy is slowly tumbling, resulting in a clear brightness variation. Ted already noted that the period of this variation changes over time, sometimes increasing, sometimes decreasing. This is in line with the tumbling behaviour of other known objects subject to SRP (like fragments of the PAGEOS balloon satellites).

click diagram to enlarge

I took a series of images between 20:19:42 UT and 20:26:12 UT (20 Sep 2015) documenting the brightness variability. The curve fits a peak-to-peak period of about 50.5 ± 0.5 seconds (see diagram above). There is clearly much variation in amplitude peak-to-peak.

The period found, is shorter than the periods found during my earlier determinations in 2009 and 2010, a summary of which is given below:

20 Sep 2015:    50.5 seconds (this post)
5 Sep 2010:     60 seconds   (see here)
20 Jul 2010:    61 seconds   (see here)
2-9 Mar 2010:   88 seconds   (unpublished)
19 Nov 2009:    62 seconds   (see here)
25-27 Aug 2009: 71 seconds   (see here)

This variation of the period over time is in line with expectations for an SRP-influenced object like this.

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Friday, September 18, 2015

Observing Geostationary satellites from Indonesia

(click images to enlarge)

In July-August this year I visited Indonesia, travelling around on the island of Sulawesi and briefly stopping over on Bali on the way back to the Netherlands. It was a special trip, in which I searched for and found the house where my grandparents and father once lived, visited archaeological sites, and in general got  to see wonderful things and got to meet wonderful people.

One of the wonderful things was the night sky - especially at the Togian islands between North and central Sulawesi. A splendid Milky-Way from horizon to horizon (image above), the zodiacal light (image below), and my first good view of the Southern Cross (second image below).

During the stop-over on Bali, I did some limited satellite observations. Geostationary objects that are never visible from the Netherlands and which I normally only get to image using a 'remote' telescope, were the focus.

Unfortunately, the lens I had intended for that purpose, my EF 2.8/100 mm Macro USM, turned out to have been damaged during the trip, to the point that it had become optically clearly faulty. I therefore had to use a decidedly less suited lens, my EF 4.0-5.6/70-300 mm telezoom. As a result, only the brightest geostationary objects did register.

Among the objects that did register were the SDS satellites USA 227 (2011-011A) and USA 155 (2000-080A), the Mentor 2 r/b (1998-029B), and two objects that initially were UNIDS although one of them could later be identified.

The first one was a bright object just north of USA 155, which I earlier had also imaged using a 'remote' telescope. It almost certainly is the communication satellite Milstar 4.

The second UNID was an object in an 7.8 degree inclined GTO  orbit that was clearly trailing in the 30 second exposures (see image below). It does not match any known object. Astrometry and a very approximate orbit for this object are here.

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Tuesday, September 15, 2015

The tumble periodicity of the Chang'e 3 upper stage (2013-070B) revisited

click image to enlarge

Brightness variation due to tumbling of the Chang'e 3 upper stage (2013-070B)
stack of 15 images taken with the 0.51-m telescope of MPC Q65 Warrumbungle
11 September 2015

I have written before on this blog about tracking very distant space debris: the CZ-3C upper stages of the Chinese Lunar missions Chang'e 2 and Chang'e 3, which move in chaotic trans-Lunar orbits. I have embarked on a long-term project to follow these objects.

Apart from positions to keep their orbits up to date, these observations also provide information about the tumbling behaviour of these objects. Both objects have a periodic variation in brightness: a very rapid one for 2010-050B, the Chang'e 2 upper stage, and a slow one for 2013-070B, the Chang'e 3 upper stage.

Earlier, in July 2015, I had established a tumbling periodicity of  ~7 minutes for 2013-070B. I have now been able to refine that value much better, to only a few hundreds of a second.

With the help of Peter Starr from Warrumbungle Observatory (MPC Q65) in Australia and Krisztián Sárneczky from Szeged University's Piszkéstető Observatory (MPC 461) in Hungary, I could obtain two nice series of data the past week. The data were gathered on September 11 (Warrumbungle 0.51-m telescope) and September 14 (Piszkéstető 0.60-m Schmidt telescope).

The first set, taken by Peter from Warrumbungle, is a set of 15 exposures of 30 seconds each, taken in ~1 minute intervals. The image at the top of this post is a stack of these images. The brightness maxima can be clearly seen.

The second set, obtained in twilight by Krisztián from Piszkéstető at the end of a run of the Szeged Asteroid Survey, is a set of 18 exposures of 3 seconds (!) each, in ~20 second intervals, with a brief pause halfway the series.

Single sinusoid fit to data from Sep 11 (lef) and Sep 14 (right)
click diagram to enlarge

The data allow to fit a sinusoid to both sets simultaniously, and from that get a very accurate periodicity. The double diagram above shows this sinus-fit to the data. It allows to establish a peak-to-peak periodicity of 423.01 ± 0.03 seconds for the tumbling of 2013-070B.

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Friday, September 11, 2015

Observing the Fregat upper stage with Galileo 9 and 10 manoeuvering into transfer orbit, just 22 minutes after launch

Fregat upper stage with Galileo 9 and 10 after shadow exit, 11 Sep 2015, 2:30:12 UTC
click image to enlarge

Last night (11 Sep 2015) at 2:08:10 UT, ESA and Roskosmos launched a Soyuz from Kourou, French Guyana, with the new navigation satellites Galileo 9 and 10. The payloads are intended for a circular MEO orbit at an altitude of about 23 522 km

Cees Bassa alerted observers in Europe to the fact that the Fregat upper stage (with payloads still attached) would be visible over Europe during it's initial orbit insertion burn, exiting Earth shadow near 02:30 UT at an altitude of about 400 km altitude while cruising over Germany/Denmark. Engine cut-off for this stage of the launch would be 2 minutes later near 02:31:40 UT

This burn brought the Fregat stage and payloads in a ballistic transfer trajectory. A second burn about 3.5 hours after launch then inserted the stage and payloads in a circular orbit, upon which the payloads separated and the upper stage was de-orbitted.

Both Cees and I managed to observe the Fregat near 02:30 UT. This was about 22 minutes after the launch. Cees observed from Drente in the Northeast of the Netherlands(closer to the trajectory and with better observing conditions), while I observed from Cronesteyn Polder at the edge of Leiden in the West of the Netherlands.

Observing conditions were mediocre at my location: the sky was hazy, and light pollution a problem at lower elevations (it can be seen as an orange glow in the image above).

After exiting Earth shadow near 02:30:00 UT at about 45 degrees elevation in Ursa major, the Fregat stage was easily seen by the naked eye as an object of magnitude +2.

Above is one of my images, a 4-second exposure (Canon EOS 60D, EF 2.5/50mm lens, 800 ISO) starting at 02:30:12 UT.

Descending towards the Northeastern horizon the object became fainter, until I lost it in the light pollution and haze about a minute later.

Cees managed to image a developing hazy envelope around the trail low above the horizon (when it was already invisible to me), which is related to engine shut-down near 02:31:40 UT.

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Monday, July 20, 2015

Rapid tumbling of the Chang'e 2 r/b (2010-050B) and Rollercoaster orbital evolution

(click image to enlarge)

Recently, I have posted several times about my tracking of two extremely remote pieces of space junk: 2010-050B and 2013-070B, the CZ-3C upper stages of the Chinese Chang'e 2 and 3 Lunar missions. These orbit in orbits with (currently) perigee just within, and apogee beyond one Lunar distance, i.e. a trans-Lunar orbit.

In a recent post I discussed the tumbling behaviour of 2013-070B, the Chang'e 3 booster. At that time, I stated that by contrast the Chang'e 2 booster, 2010-050B, appears steady.

I can now say that is not true: 2010-050B is tumbling too. And very rapidly, which is why I didn't notice it earlier.

My earlier imaging sessions were done while 2010-050B was at well over one Lunar distance (beyond 400 000 km), towards its apogee. On July 18th I imaged it from MPC Q65 Warrumbungle while it was only a few hours from its perigee, at a distance of 280 000 km (about three quarter of a Lunar Distance), moving at 47" per minute. The result is a much longer trail on the image than in earlier imaging sessions.

Rather than being a trail, suddenly the trail is resolved in a series of dots: typically three (and in one image two) per 30 second exposure. See the image in the top of this post. The reason this was not visible during earlier imaging sessions, was that the trail was so short (a  few arcsecs) when imaging the object at larger distance, that the dots merge into one trail.

The 3 dots per image, and once two dots, indicate a flash period of ~15 seconds, testifying to a rapid tumble. This is close to the period determined by Peter Birthwhistle (MPC J95 Great Shefford) in 2010 shortly after the launch.

I also imaged 2013-070B that night, at a distance of about 479 000 km (1.25 Lunar Distances). This object is tumbling much slower than 2010-050B: the brightness variation in the animated GIF below fits nicely with the 7m 05s flash period determined from June 26 and July 5.

The orbits of 2010-050B and 2013-070B are changing extremely fast, in a chaotic way, notably as a result of Lunar perturbations. As you can see in the table that is part of my SeeSat-List post here, the apogee of the 2010-050B orbit for example changed from about 550 000 km to about 446 000 km between May 7 and July 18. The perigee changed from about 350 000 km to about 280 000 km, i.e. from about 1 Lunar Distance to about 0.73 Lunar Distance, during that same period. The orbital period was shortened by almost 10 days.

While the apogee and perigee distances are currently decreasing for this object, a new Lunar perturbation might make them increase again in the future. The orbital inclination also widely varies over time. Such changes are very sudden, especially in connection to close Lunar encounters. These objects are on a true Rollercoaster ride through the Earth-Moon system.

As it turns out, this kind of chaotic orbit is very difficult to model, even over relatively short time scales. Attempts using GMAT show that very small variations in the determined orbit yield very different outcomes within only a few years. Variations in the order of a few hundred meters (!) in apogee and perigee will already do it, i.e. variations well within the uncertainties in the determined orbital parameters.

GMAT-simulated chaotic orbital evolution of 2010-050B over a 1.5 year period. Grey is the Moon orbit, red is 2010-050B orbit, blue grid is earth equatorial plane. In reality, the orbital evolution might be different as small variations in initial conditions (see text) yield large differences after 1.5 years.

So we have to observe these objects to see how their orbits evolve in the future. And this is what I will do: keep following them, over the coming years.

Basically, three eventual future fates are possible for these objects: one is eventual ejection into a Heliocentric orbit (so it will leave the Earth-Moon system); two is an eventual Earth impact (i.e. a decay in the Earth atmosphere); and three is an impact on the moon.

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