ISS transiting the Sun

click image to enlarge

Yesterday (June 23, 2014) near 16:15:29 UT (18:15:29 CEST), the International Space Station (ISS) passed in front of the solar disc as seen from my observing location in downtown Leiden. As can be seen in the picture above, the transit was nearly central (the calculated central line was 600 meter to the north of me). The whole event had a duration of about 1.5 seconds, during which 9 photographs captured the Space Station silhoueted against the sun. The images were made with my Canon EOS 60D through my Celestron C6 (15 cm Schmidt-Cassegrain), fitted with a Solar Screen filter and an F/6.3 focal reducer. The sun was low in the sky at an elevation of 31.8 degrees due West. The inset is a stack of the 5 best ISS silhouets.

The images are not perfectly sharp, which is due to air turbulence (even at 1/4000 second) and the simple fact that I find it quite hard to focus the telescope properly on the sun, certainly when it is almost featureless. Nevertheless, I am satisfied with this image.

I knew of the transit because I subscribe to alerts from CalSky for this kind of phenomena. In preparation for the actual observation, I download the latest ISS elements from Space-Track a few hours before the event, and load them into Guide to fine-tune the transit time and the path over the solar (or lunar) disc. Starting about 1 second before the calculated commencement of the transit, I start a rapid burst series of images at 5.7 images/second.

click images to enlarge

Above are two pictures of the setup used. The filter mount is homebrew and quite simple (from thin cartboard). The filter itself is Solar Screen, a mylar filter with a double thin aluminium filter coating. Using such a filter makes it safe to look at the sun (NEVER look at the sun without a proper filter!).

In order to be able to see anything on the camera LCD screen in the bright sunlight, I put a towel over my head and the telescope back during focussing.

[UPDATED] Three UNID's in GEO/GTO/HEO/MEO, SBIRS GEO 2, and Lacrosse 5 has manoeuvered

Updated 14:35 UT (Jun 23) to reflect that I found a third UNID on my imagery after writing the original post

click image to enlarge

Saturday/Sunday night 21/22 June was very clear. As I had some trouble getting to sleep, I decided to make use of it to do a survey of the GEO belt, from my secondary site Cospar 4355 which is in the polder just outside of town, some 10-15 minutes by bicycle. The sky is a bit darker there and I have a better view to low elevations. Using the 1.4/85mm Samyang lens, I can expose twice as long as I can from my regular town center site 4353. The downside: so many objects on the images to identify and measure....

This observing site, in a polder park with meadows and polder ditches, is very tranquile. A choir of frogs was chanting during my observations, and meadow birds were adding their voice too. As I was observing, a low blanket of ground fog started to form, with my camera on tripod popping up just above it.


Two Three UNID's

At the moment I am still slowly working myself through the 54 images taken, identifying objects, but I can already report that I captured two three UNID objects (for positions on the 3rd see here), two in GTO/GEO and one in MEOor HEO. They are not in the Space-Track catalogue nor in our classified catalogue.

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UNID 1 was observed as a small trail on several images taken between 23:05:32 and 23:23:32 UT (June 21). The 15 second image above shows it near the SIGINT satellite Mentor 4 (2009-001A) and is the first image that captured it. It looks like something in GTO and a very cautious orbit fit to this short 18 minute observation arc indeed suggests a GTO-like, roughly 13160 x 36945 km, 12.8 degree inclined orbit with a period of ~1.6 revolutions per day:

UNID 1                                               13160 x 36945 km
1 00000U 00000X   14172.96808160 0.00000000  00000-0  00000+0 0    05
2 00000  12.7577 311.8608 3783132 187.8049 143.4679  1.55784798    00

click image to enlarge

UNID 2 was detected on only two 20 second images taken half a minute apart. It is less trail like (see image above), but slowly moving south when the measurements on the two images are combined. It is either in a somewhat inclined GEO orbit or a GTO object near apogee.

The image above also shows SBIRS GEO 2 (2013-011A), a classified geostationary SBIRS satellite (an Early Warning satellite looking for missile launches in Infra-Red). In addition, an old Russian r/b and a Russian military GLONASS (the Russian equivalent of GPS) satellite are visible. Star trails are slightly blurry because the FOV represents a detail near the edge of the image.

click image to enlarge

[UPDATE] 
UNID 3 was detected close to alpha Serpens in only two 20 second images taken 1 minute apart.  It is clearly trailing. The positions fit either a circular MEO orbit, or a HEO orbit (the observation arc is too short to discriminate). Above, the two images that captured it are shown.


Lacrosse 5 appears to have manoeuvered

The same image that captured UNID 1 also captured the military Radar satellite Lacrosse 5 (2005-016A, see image in top of this post), just as it was emerging from Earth shadow. It was about 54 seconds late relative to 8-day-old elements. That is a lot for only 8 day old elements. Hence it appears to have manoeuvered somewhere in the past few days.

Prowler flaring

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I have written on the enigmatic Prowler satellite (1990-097E) before. I periodically observe it using a 'remote' telescope (usually the 0.61-meter Cassegrain of SSON, MPC G68).

On 2014 June 10 I captured it briefly flaring - I had not observed that before, though other observers had. The brief flare can be seen near the edge of the image (the trail runs out of the FOV) in the lowermost of the two images above.

Approximate positions of this flare:

- begin RA 17 25 24.73 DEC -20 49 41.7
- maximum RA 17 25 26.15 DEC -20 49 45.2
- end RA 17 25 27.36 DEC -20 49 45.6

Extrapolation from the measured timed positions above, gives the following approximate times for the flare:

- begin 09:25:23.9 (UT, 10 June)
- maximum 09:25:25.3 (UT, 10 June)
- end 09:25:26.5 (UT, 10 June)

Apart from these short flashes, observers report a much slower brightness variation. Indeed, I had suspected such from my own observations, as the trail brightness widely varies (between bright and completely invisible) between different image sessions. On May 27 for example, I also tried to image Prowler using the same 0.61-meter telescope, but it was invisible.

As Allen Thomson remarked, part of this brightness behaviour might be due to Prowler's former stealth characteristics.

Tracking USA 161

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I am a bit behind with posting the image above taken a week ago, on 3 June 2014 . It shows the KH-11 Keyhole/CRYSTAL optical reconnaissance satellite USA 161 (2001-044A), which was recently recovered.

With new observations including mine, the orbit is now getting better defined. During the winter blackout, the orbit of the satellite appears to have been further circularized to a 389 x 391 km orbit, by a small perigee rise.

In the image above, another object is also visible: a Falcon 9 r/b, 2010-066K, at over 5000 km altitude at that time.

Telescopically imaging the ISS (plus some deep-sky)

So far, my satellite imaging has always been done with a DSLR and normal camera lenses and were essentially 'wide field'. The largest focal length I so far used was 180 mm.

click images to enlarge

Last week I have experimented with telescopic imaging of the International Space Station (ISS), using my Celestron C6 (15 cm F/10 Schmidt-Cassegrain). Above is the best image, shot 6 June 2014 at 22:07:13 UT as the ISS was zipping past beta Bootes. It is a single image from the series, taken at 1/4000th second at ISO 800.

I kept it simple: I did not actively track the ISS, but looked for points where it passed close to a reasonably bright star, and then pointed the telescope to that position. As the ISS passed that point, I did a rapid burst series of images, a few of them which then showed the ISS zipping through the field. I used 1/4000th second exposures.

That technique is actually enough to get some decent pictures. Later, I will probably experiment with active tracking using computer guidance of the mount, and see whether video might yield more that photography (one drawback of video is a lower resolution, so a need to work with Barlows).

Having the telescope out anyway, I made some deep-sky images too the last two nights, of some bright summer sky icons. Again, I kept it simple. As I work from a town center, and a location where I cannot see the Pole star due to obstruction by a building (which hampers telescope alignment), I kept exposure times short, to 10-15 seconds. Then I stacked large numbers of images.

click image to enlarge

The above image of M27, the Dumbbell nebula, a planetary nebula in Vulpecula, is my favourite. It is a stack of 57 images of 15 seconds exposure each at 2000 ISO. The faintest stars on this image are near mag. +16.8, which is not bad with short exposures from a town center.

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Another iconic planetary nebula in the summer sky is M57, the Ring nebula in Lyra. The image is on the same scale as that of M27 above. This image is the result of stacking 60 images of 10 seconds exposure (the scope didn't track that well that night) at 1600 ISO.

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The final image shows globular cluster M13 in Hercules. It is a stack of 57 images of 15 seconds exposure, taken at 2000 ISO.

Sorting out the confusion: USA 161 and IGS 8R

Okay, so yesterday considerable confusion arose about the current orbit of USA 161 (see previous post). This was due to the (luckily shortlived) confusion between two objects: the real USA 161, and a Japanese spysat that was briefly mistaken by me for USA 161.

The object which I photographed during the night of May 30-31 and which Björn Gimmle photographed from Sweden on April 22, turned out to be not USA 161 but, as Cees Bassa pointed out, another classified object we had "lost" in the winter blackout: IGS 8R (2013-002C), a Japanese radar imaging satellite launched early 2013.

So the image below actually shows IGS 8R flaring brightly, not USA 161 as I initially thought:

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Luckily, Russell Eberst in Scotland observed the real USA 161 on June 1. Together with the observation by Leo on May 23, this means we do have an idea of the current orbit of USA 161 now, although further refinement through more observations is necessary. What is clear, is that USA 161 still is in the same orbital plane it was in when we lost it in August 2013. It's RAAN difference with the primary East plane KH-11 USA 224 is still 20 degrees, and it's orbit is sun-synchronous and about 385 x 393 km (these are approximate values which are subject to change, as the current orbit is preliminary and needs some refinement with more observations). The current KH11 Keyhole/CRYSTAL constellation now looks like this:

The short-lived confusion of yesterday could arise because both objects (IGS 8R and USA 161) currently move in a similar orbital plane. This can be seen in the image below, where the IGS 8R orbit is yellow and the USA 161 orbit is light grey:

This is the kind of confusion that can arise when multiple objects who's orbit have not been recently updated, move in a similar orbital plane. It does not only happen to us amateur trackers: even the professionals at JSpOC sometimes confuse objects.

Actually, this situation ended positive with a double recovery: that of USA 161, and that of IGS 8R.

[AGAIN UPDATED] USA 161 recovered (?) - and new ideas on changes in the KH system

CORRECTION 1 June 2014: The object I observed on May 31 turns out to be NOT the KH USA 161, but one of the IGS objects, IGS 8R (2013-002C) which we had 'lost' in the winter blackout, just like USA 161. Their orbital planes happen to be very close (with a few tenths of a degree in inclination and a few degrees in RAAN) at the moment.

This renders the whole story below incorrect and hence moot.

Luckily, Russell Eberst did observe the real USA 161 last night (June 1) and his observations fit with Leo's observations from May 23. More in a new post later. (this new post is up now here)

ML, 01/06/2014

- STOP PRESS - (31 May 2014, 19:00 UT). Okay. Cees Bassa thinks last night's object is not USA 161. See here. So read the story below with caution: the jury is still out on all this.

Although it all was/is a bit confusing, it appears USA 166 (2001-044A), the secondary East plane KH-11 Keyhole/CRYSTAL has finally been recovered. [UPDATE: OR PERHAPS NOT???]. It had not been positively observed since August 2013 and over the past half year had been hiding in the northern hemisphere winter blackout.

USA 161 ?. IGS 8R last night

(click image to enlarge)

Initially, Leo Barhorst in Almere (NL) appeared to have recovered it on May 23. However, his observed object now turns out to not have been USA 161 but an unidentified other object.

Last night it was clear, after a very rainy week. Suffering from a bout of insomnia, I took advantage of the clear skies by conducting a 30 minute plane search, from 01:00 UT to 01:31 UT (May 31), using the EF 2.0/35 mm wide angle lens.

Just as I was about to abandon the effort at 01:30 UT, a bright and fast satellite appeared with a direction that was correct for USA 161 in a generally correct area of the sky. I managed to capture it on two images, the second one of which is depicted above. The object was about mag +2 when I first visually picked it up, and then becoming brighter as it produced a slow flare to mag -2 near 01:30:27 UTC. The image above shows the slow flare moment. It moved fast, producing long trails on the 10 second images with the 35 mm wide angle, so it evidently was near perigee.

The object could not be matched to any known object, but did appear to move in the general secondary East orbital plane of the KH-11. Visually, the slow bright flare it showed was quite typical for the KH-11 too. So I was (and am) fairly certain it is USA 161. Or not? Problem was, my observation was difficult to match with Leo's observation a week earlier...

After I reported my observations, Ted Molczan next managed to positively match my object to a UNID observation by Björn Gimmle in Sweden on April 22 (so over a month earlier), proceeding to fit a very reasonable orbit. The suggestion of this all is, that Leo's object from May 23 was something else, as it does not fit well with the other observations.

The preliminary orbit calculated by Ted, which needs to be refined by further observations, suggests that USA 161 made a manoeuvre into a (compared to the orbit it was last seen in in 2013) slightly higher orbit of 411 x 425 km, with the orbital inclination changed by half a degree to 97.52 degrees. This is the same orbital inclination as USA 129 (1996-072A), the former secondary West plane KH which we have recently "lost" and which is suspected to have been de-orbitted, was orbiting in.

Like the drifting secondary West plane KH USA 186 (2005-042A, see several previous posts on this blog for a discussion), USA 161 is no longer sun-synchronous as a result of this manoeuvre, and hence in what appears to be a plane transfer orbit. Its distance in RAAN relative to the primary East plane KH-11, USA 224 (2011-002A), has increased and will keep increasing steadily until it makes a corrective manoeuvre (which I suspect will happen near June 12, see below).

The orbital constellation for May 31 looks like this:

(image removed)

click image to enlarge

The current situation is that the two new primary plane objects, USA 224 and USA 245, are keeping a more or less steady plane distance (in terms of RAAN) of 48.5 degrees. The two (older) secondary plane satellites, USA 186 and USA 161 however have now both lost sun-synchronicity, and are both drifting outwards with respect to the orbital planes of their corresponding primary plane satellite.

Frequent readers of this blog will remember that I initially expected USA 186 to manoeuvre back into a non-drifting sun-synchronous orbit when the RAAN difference with USA 245 was 10 degrees, early February. That didn't happen. As a secondary option, I then thought it would manoeuvre when the difference was 20 degrees, early May. That didn't happen either. I then was at a loss as to what "they" were planning to do with USA 186.

Now USA 161 has been recovered and turns out to have been manoeuvered into a drifting plane-changing orbit as well, just like USA 186, I am getting a possible idea again about what they might intend. Please note: I have been wrong twice before, so my track-record in these kind of predictions is not quite good :-p

Nevertheless: assuming that symmetry is what is being aimed for, I think both objects (USA 186 and USA 161) will manoeuvre back into a non-drifting, sun-synchronous orbit on or near June 10 to June 12.

On May 31 the RAAN difference between USA 245 (primary West) and USA 186 (drifting secondary West) was 23.0 degrees. The RAAN difference between USA 224 (primary East) and USA 161 (drifting secondary East) was 23.7 degrees. Their rate of drift is different: it is -0.11 degrees/day for USA 186 and +0.056 degrees/day for USA 161 (i.e., USA 186 is drifting twice as fast as USA 161). These differential drift rates mean that at some point in time, both satellites will reach a matching value in RAAN difference with their primary partner, i.e.be at similar RAAN distances from their primary partner on the same day. This is depicted in the diagram below:

(image removed)
click diagram to enlarge

What can be seen from the diagram, is that this moment will occur in about 10-12 days from now, near June 10-12. On June 12, both satellites (USA 186 and USA 161) will reach a matching difference in RAAN of 23.3 degrees with their primary partners USA 245 and USA 224. Interestingly, this value is very close to 0.5 times the RAAN difference between the primary plane satellites, USA 224 and USA 245 which are 48.5 degrees apart in RAAN.

But please be advised: until now, I was wrong each time I thought I could make sense of it....

USA 224 recovered, USA 186 still drifting, and looking for GPS IIF-6 20 minutes after launch

For various reasons, I am a bit late in keeping the reader up to what is happening to the KH-11 Keyhole/CRYSTAL system of optical reconnaissance satellites.

USA 186 (2005-042A), the secondary West plane KH-11, is still in a non sun-synchronous orbit and hence still drifting westwards. It is drifting for over half a year now. The difference in RAAN with USA 245, the primary West plane KH-11, is now over 20 degrees (21.8 degrees on May 19th). I am very curious as to when the drifting will stop, if ever. If it continues to drift for many weeks to come, we should contemplate whether perhaps the satellite is "dead", i.e. has lost manoeuverability. Problem is that NW European observers temporarily have lost visibility of the satellite, due to the current short nights. Tracking all comes down now to observers in the US and southern Europe.

Meanwhile, Russell Eberst in Scotland recovered USA 224 (2011-002A), the primary East plane KH-11, on May 9th. It is in a 260 x 1006 km orbit, which means it has slightly lowered its apogee. Before the winter blackout it was in a 258 x 1023 km orbit. The difference in RAAN with USA 245, the primary West plane KH-11, is now 48.5 degrees.

My own first observation of USA 224 was in the night of May 16-17. The image below shows it crossing through Corona borealis:

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USA 161 (2001-044A), the secondary East plane KH-11, has still not emerged out of the winter blackout. Meanwhile, USA 129 (1996-072A) has gone missing since April 24 (see a previous post). There is a good chance it has been de-orbitted.

The current KH-11 constellation now looks like this (where the current orbital configuration of USA 161, in red, is uncertain, and USA 129 left out as it is no longer in its old orbit, and presumed de-orbitted):

click images to enlarge

In the early morning of May 17 (evening of May 16 in the US) and after a one day delay due to bad weather, a new GPS satellite, GPS II-F6 was launched from Cape Canaveral on a Delta IV rocket. It would pass over the Netherlands some 20 minutes after launch, still ascending and still attached to the 2nd stage. A number of search orbit had been published, but it looks like none of these was very accurate. I visually observed a bright UNID near 00:24:00 UT (May 17) moving just a few degrees to the 'right' of Altair on a trajectory parallel to the predicted ones but some 20 degrees cross-track in a southern direction. It was already descending over the roof when I picked it up, so I had no time to snap a picture alas. It did not match any known object so I am quite confident it was GPS II F-6 on its way to orbit. It was bright, about mag +1 to 0.

KH-11 USA 129 is missing, USA 186 has still not manoeuvered

USA 129 (96-072A), the oldest of the KH-11 Keyhole/CRYSTAL/KENNAN optical reconnaisance satellites, has gone missing. The last observers to see it were me on April 22 and Russel Eberst on April 24. The photo below shows one of my images from April 22, with USA 129 passing near Castor and Pollux:

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Somewhere between that date and May 1, when various observers noted it missing, it disappeared.

There is a possibility that it has been de-orbitted, as it is over 17.5 years old now and appears to be 'redundant' after the launch of USA 245 and plane move of USA 186 (see various earlier posts on this blog). On the other hand, we should be cautious and not too hasty: in the recent past (Feb 2014) we erroneously wrote USA 129's eulogy before, and it turned out it had just manoeuvered. Maybe it did this time as well. A dedicated plane watch I did in the evening of 3 May between 20:41 -21:05 UT yielded nothing.

Meanwhile, we had expected USA 186 (2005-042A) to manoeuvre early May. But up to yesterday May 4th it hasn't. Maybe it will do in the coming days. On May 1st the difference in RAAN with the main West plane KH, USA 245, was 19.8 degrees. At a drift rate of 0.11 degrees/day, it reached 20 degrees the past weekend. If it hasn't manoeuvered by the end of the coming week, it will become interesting. Unfortunately, it is disappearing in evening twilight for my location these days.

The image below shows USA 186 crossing Canis minor in deep evening twilight of May 2nd:

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I imaged USA 245 (2013-043A), the current main West plane KH-11, last Saturday evening. In evening twilight, it was visible in the same camera field with FIA Radar 1 (2010-046A):

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Imaging SWARM A and C

On 22 November 2013, ESA launched SWARM, a group of three futuristically looking scientific satellites (2013-007A, B and C) whose purpose is to map the strength, variation and structure of the Earth's magnetic field. Two of the three operate as a close pair in a similar orbital plane at 460 km altitude, the third at 530 km altitude will eventually orbit at an angle to the orbit of the other two (the orbital plane is currently still quite similar, but that will change over the coming years).

The satellites look like a cross between a techno aardvark and a vacuum cleaner:

image credit: ESA

On the night of May 3-4 I was taking images with the EF 2.0/35mm wide field  in an attempt to recover KH-11 USA 224. I did not recover USA 224 but my images showed a number of objects. Including a serendipitous catch of the SWARM A & C duo (2013-007B & C) crossing through Cygnus near 23:32:02 UTC.

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The yellowish whisps in the image are clouds. SWARM C shows a bright flare near the start of its trail, then the brightness suddenly drops. SWARM A is faint.

[UPDATED & CORRECTED] Observing the SpaceX Dragon CRS-3, the ISS and two pieces of Dragon launch debris

CORRECTION (21/04/2014 12:55 UT): in the initial post, the two debris pieces were misidentified. "2014-022C" turned out to be 2014-022H, and "2014-022H" turned out to be 2014-022G.

click image to enlarge

Last Friday at 19:25 UT, SpaceX launched the Dragon CRS-3 commercial supply ship to the International Space Station ISS. It passed over Europe 20 minutes later but unfortunately I was clouded out in Leiden. In the middle and eastern parts of the Netherlands as well as elsewhere in Europe, observers were treated to a spectacular view of the Dragon, the Falcon upper stage, and two faint pieces of debris passing by as a thight group of objects.

SpaceX Dragon CRS-3
click image to enlarge

I was more lucky yesterday when the sky was clear and the Dragon and ISS made a late twilight pass culminating at approximately 26 degrees altitude in the SW near 20:06 UT (22:06 local time, sun at -12 deg.). The image above shows the Dragon CRS-3 due south already somewhat past culmination. It was easy to see with the naked eye, attaining magn. +1.5. Its brightness is more similar to a Progress or ATV then to the much fainter commercial Orbital Sciences Cygnus.

The Dragon was about 1m 12s behind the ISS, a visual distance of somewhat over 40 degrees. Pre-observation predictions based on elements a few hours old had put it in front of the ISS, so at first I was wondering whether I missed it. Then, as the ISS was descending towards the SE, I saw it approaching in the SW, chasing the ISS. A very fine sight!

The ISS passing the same sky area as the

earlier image, 1 min earlier

(click image to enlarge)

While I was photographing at the nearby city moat, I had also set up the video in my girlfriend's appartment, and this capture both objects as well: first the ISS, then a minute later the Dragon:




(the display says "GPS BAD" because my GPS time inserter failed to lock on a GPS satellite. I hope it is not broken...)

Apart from the Dragon and the ISS, I observed and photographically imaged a third debris object related to the launch. It is the object catalogued by JSpOC as 2014-022C/#39682. 2014-022H, #39687. It is either the jettisoned Dragon nose cone cover, or one of the solar panel covers   or possibly one of the Nanosat dispensers: I think it is too bright to be one of the several released nanosats itself. It was faint and slowly tumbling, alternating between invisibility and a max magnitude of about +3.5:

tumbling Dragon debris 2014-022H

(click image to enlarge)

[UPDATE:] Later I discovered a second piece of Dragon CRS-3 launch debris on my imagery. It is faint, irregular in brightness and present on two images, the best of which is this one from 20:04:07 UTC:

tumbling Dragon debris 2014-022G
(click image to enlarge)

This turns out to be the object designated 2014-022H, #39687  2014-022G, #39686. This is the other solar panel cover.

Progress M-22M in twilight

Yesterday evening in late twilight (sun 11 degrees under the horizon, waxing gibbous moon low in the sky) I observed Progress M-22M (2014-005A), the Russian cargoship that undocked from the ISS on April 7.

 click image to enlarge

The undocked Progress will be flying solo for several days, during which ionospheric tests are conducted. It will be de-orbitted on April 18 near 15:43 UT.

As usual, the Progress spacecraft was easily visible to the naked eye, reaching about mag. +2. It passed between Gemini and Canis minor (and roughly halway between Procyon and Jupiter, see image above), then over the head and body of Leo and through the Coma Berenices cluster (see imagebelow) before disappearing behind the roof. It was about 25 minutes ahead of the ISS.

click image to enlarge

25 minutes later I did a first attempt to image the ISS in high resolution through my C6. I managed to get two images of it, but they are not of good quality. I guess I have to practise a bit more :-)

Eagle Eyes

Recently I posted a topic on USA 184, one of the SBIRS-HEO satellites. That post was illustrated with amongst others this patch:

click image to enlarge

A sharp eyed reader, graphic designer and illustrator Olivier Rossel (PXP), noted something odd in the patch. More exactly, in the bothom "beard" of feathers of the Eagle's head.

I had not noted it until Olivier pointed it out (and it is so obvious now!), but letters are spelled out there:

(image courtesy of Olivier Rossel)

You can read the words "GEO", "DSP" and "HEO". These are all relevant to the US Infrared Early Warning system. SBIRS has satellites in two kind of orbits: GEO (geosynchronous) and HEO (Highly Elliptical Orbit - see my earlier post). DSP is the Defense Support Program, the predecessor of the newer SBIRS, consisting of a number of satellites in GEO.

Some Russian guy, Ivan Karavay, identified the words earlier in a post in this forum (in Russian) but I had never seen it until Olivier pointed it out to me.This while I knew words are sometimes hidden in NRO-related patches. Take these patches for example, from the NRO launches NROL-25, NROL-34, NROL-41 and NROL-49:

click images to enlarge

In the "vermicelli" that fills in the Earth in these patches, letters can be discerned that sometimes solve into acronyms: "4 SLS" (4th Space Launch Squadron),  NRO or NROL, and other letter combinations that are less easy to interpret.

Speaking of logo's and patches: I recently re-designed the logo of SatTrackCam. The new design is based on the older design but less cluttered:

click image to enlarge

Like in NRO patches, there is some coded information in this design: the Coat of Arms for example has a double meaning. The (pig-) Latin actually refers to a notorious NRO patch, as well as a famous internet meme.

[updated] The bright fireball over Germany of 31 March 2014, 22:34 CEST: an earthgrazing meteor, not a satellite re-entry

[updated 20:55 UT (1/4/2014) to reflect revised fireball duration]

Yesterday evening German astronomical internet fora and my Twitter timeline erupted in a frenzy about a very bright, magnitude -10, west to east moving, very long duration fireball seen over southern Germany near 20:34 UT (22:34 CEST, March 31).

The fireball was widely seen by eye witnesses and captured by a video all-sky station near Ulm. The very spectacular image, by Thomas Tuchan, can be seen here (scroll down in the message list) on the AKM message forum.

As usual, it was science writer Daniel Fischer who was the first to knock on my digital door for an opinion. The question that had popped up, as it does with every long duration slow fireball, was whether this was a meteoric fireball or perhaps a satellite re-entry? In most cases, it is not, although there are exceptions.

My first check in such cases always is with JSpOC to see whether there was a suitable re-entry candidate in the TIP-messages. There was not. This while a re-entering artificial object of this brightness must be a very big object, for which you expect a TIP message.

Next more information came available on the fireball length and duration, notably through Thomas Tuchan's all-sky video image. It shows an almost horizon to horizon event, with a duration of 16 33 seconds. It starts at approximately 15 degrees elevation in Perseus, culminates at 60 degrees North, and ends low on the opposite horizon, at an elevation of about 12 degrees. A span of some 150 degrees!

[Update 20:55 UT: the duration was later revised to 33 seconds]

The very long 150 degree trajectory with a duration of 16 seconds rules out the re-entry of an artificial object. It shows that this was a meteoric fireball, and one that entered the atmosphere at a very shallow angle: a so called Earthgrazing meteor. There are even some examples (most famous one the Grand Tetons fireball of 1972) where such Earthgrazing fireballs left the Earth's atmosphere again!

Satellite re-entries take place between 150 and 50 km altitude. At such altitudes, an earth-orbiting object has a speed of 7.5-7.8 km/s and the resulting apparent angular velocity is about 3 degrees/second for 100 km, and about 5 degrees/seconds for 50 km altitude: but only in the zenith. Lower above the horizon, the angular speed is much less.

I constructed an artificial set of orbital elements for an orbital altitude of 90 km (re-entry in progress) as a test: it takes such an object 1 minute 15 seconds to move from 15 degrees elevation above the western horizon to 15 degrees elevation on the opposite horizon. By contrast, it took the German fireball only 16 33 seconds: i.e. almost a factor two-and-a-half faster.

[Update: the duration was first reported as 16 seconds, later revised to 33 seconds]

All this makes very clear that the German fireball of March 31 was not the re-entry of an artificial object, but a meteoric fireball, most likely an Earth-grazing object of asteroidal origin..

Observing USA 184 (TRUMPET-FO/SBIRS-HEO)

It had been a while since I last observed objects in HEO (Highly Elliptical Orbit). Most of my recent focus has been on the KH-11 in Low Earth Orbit and on geosynchronous objects.

USA 184, 29 March 2014, 21:34 UTC
click image to enlarge

Last Saturday evening I however targetted USA 184 (2006-027A), a classified US military satellite in HEO which hovered almost in the zenith for my locality during the observation. It is the tiny trail indicated by the arrow in the image above, taken with my Canon EOS 60D and a 2.8/180mm Zeiss Sonnar MC. Stars in the image belong to Ursa maior.

A Highly Elliptical Orbit (HEO) is an orbit which is highly eccentric ("elliptical") with a low perigee at only a few hundred kilometers altitude (usually in the southern hemisphere) and a high apogee, often in the 20 000 to 39 000 km altitude range. The orbit is typically inclined by about 63 degrees.  USA 184 is in a 63.58 degrees inclined, 1590 x 38 760 km orbit.

USA 184, orbital position 29 March 2014 21:34 UTC

click image to enlarge

Satellites in such an orbit spend a long time near the apogee of the orbit. As a result, they hover high above the northern hemisphere for many hours a day. Just like a geosynchronous orbit, this allows long duration coverage of a (large) area. The difference with a geosynchronous orbit is that a HEO orbit is well suited to cover high polar latitudes, while a geosynchronous orbit has a poor coverage of such high latitudes. HEO orbits are therefore typically used for applications that demand long-duration coverage of high Northern latitudes. It concerns communications satellites (notably by the Russians), SIGINT satellites and Infrared Early Warning satellites.

USA 184 falls in the latter two categories. It is a TRUMPET-FO (the FO stands for "follow-on", i.e. it is an improved version of the older TRUMPET) SIGINT satellite. In addition, it has a piggyback SBIRS (Space Based Infrared System) package, which is dedicated to the detection of ICBM launches by their Infrared signatures. It is one of two HEO sensors in the SBIRS system (the other one is on USA 200, 2008-010A), in addition to the two dedicated SBIRS satellites in geostationary orbit (SBIRS-GEO 1 and SBIRS-GEO 2, 2011-019A and 2013-011A).

At the time of the observation, USA 184 was at an altitude of  38 355 km over the Northern Atlantic at 62.74 N, 4.84 W. It was almost in its apogee, and hovered at 76 degrees elevation in the sky. This is the approximate view from the satellite at that time:

view from USA 184, 29 March 21:34 UTC

click image to enlarge 

The images below are uniform patches related to the launch of USA 184 (as NROL-22 on 27 June 2006), and the SBIRS program:

note: the orbital diagrams were made with JSatTrak software and amateur orbital elements calculated by Mike McCants.