The flash period of USA 81 on June 2nd (UPDATED with February 24 results)

In my previous post I reported on a bright stroboscopic flash display by the SIGINT satellite USA 81 (92-023A) on June 2. I now had some time to analyse the images. Below are diagrams showing the brightness behaviour in the two images that captured the event.

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In the first image, the median period between succesive peaks is a very neat 0.20 seconds (average: 0.18s; modus: 0.19s). The same period also is present in the series from the second image, but with more "noise" in terms of either extra "peaks" or missing peaks. Below images shows it as diagrams of the delta time between peaks, and the deviation of these to the 0.20s period established by the first image:

click diagrams to enlarge

The results compare with similar results I obtained in February this year, which for some reason I never published on this blog. These are diagrams from my February 24, 2010 observations (two images), when it showed a series of sharp glints in the zenith, similar to those of June 2nd, with a period of ~0.41s (multiple of the 0.20s of June 2nd). Lower in the sky, it changed to a slower cycle of less sharp peaks with a period of 1.26s.

click diagrams to enlarge

The brightness behaviour hence is quite similar to that for it's older sister ship USA 32 (see here).

USA 202 and other geostationaries, and a stroboscopic show by USA 81

I am awfully behind with reporting on my observations.

In deep twilight on June 2nd, I observed USA 81 (92-023A) briefly attaining easy naked eye magnitudes in Bootes, and firing off a rapid series of flashes. The trails on both images covering this episode of bright stroboscopic behaviour partly run off the image, as I re-aimed in (too much of) a hurry. I still have to analyse the flash period. But it was impressive to see:

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Apart from two Lacrosses, I also targetted the geostationary satellite Milstar 5 (02-001A) again. below image shows it together with the commercial geosats Galaxy 11 and Intelsat 802:

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I also imaged another classified geostationary satellite, USA 202 (09-001A), and ELINT satellite (probably a Mentor/Advanced Orion). I had not realised it was so bright, so initially I thought the faint object on below image was USA 202 and the brighter one the commercial geosat Thuraya 2. However, the brighter object is USA 202, as it turns out (hence, the questionmarks still in below image can be removed). The satellite is at an altitude of only 17.5 degrees in the south-southeast for mu location.

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USA 198 brightness behaviour: a belated 2nd report

A belated report on a second instance of USA 198 (07-060A) flaring.

On May 13th I captured another one of such instances, after first capturing it on May 5th (see report here, 2nd part of that post).

On May 5th I captured it decreasing in brightness froma prominent brightness peak. This time, I captured it increasing in brightness towards a prominent peak near 21:44 UTC, with a hint of the start of a decrease later. Here is a selection of images, all spaced 1 minute apart:

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The first 11 images in the series yield the curve below (I did not include the rest of the images, as they are all saturated)

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Both this May 13 and the earlier May 5th flaring occurred close to the moment that the sun, observer and satellite lined up, indicating it is probably due to reflection on the solar panels.

An IGS 1B flare, and Geostationary satellites again

Last evening 25-26 May was not the best of evenings: cirrus, and moonlight, plus this time of the year the sky darkens late and in fact remains in twilight all night at 52 N.

In twilight, I observed the KH-12 KeyHole USA 186 (05-042A), IGS 1B (03-009B), and Lacrosse 4 (00-047A). Short after midnight, the still flaring commercial geostationary satellite Galaxy 11 (99-071A) and the classified military geostationary satellite Milstar 5 (02-001A) were the target.

IGS 1B slowly flared to mag. -0.5 at about 21:15:48.5 UTC (May 25), while the camera was open. below photograph shows the brightnes speak, when it was cruising close to the Coma cluster:

click image to enlarge

IGS 1B is a defunct Japanese Radar Reconnaissance satellite. Since it went out of control, it is producing flares occasionally (sometimes up to mag. -3 to -5 peak brightness).

Galaxy 11 was flaring again, but is getting fainter at its peak. If my modelling is right, it might flare again in a new cycle around the 3rd week of July. Below link provides an animated GIF of last night covering 20 minutes with the geosat flaring up. Milstar 5 is in it as well, moving southward.

Link: animated GIF ( 5.5 Mb)

Around 22:10 UTC, Intelsat 802 (97-031A) briefly flares up close to Galaxy 11. It stays faint, but is visible. The single image below might help discern it:

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Geostationary Galaxy 11 flaring to mag +2.5

In my post of yesterday, I reported a bright geostationary satellite flaring to naked eye brightness, observed by several Dutch and Belgian observers.

Below are my images of last night (taken with the EF 50/2.5 Macro). It shows two "stars" "too many" in Ophiuchus: a brighter one (A, vertical arrow) and a fainter one (B, flat arrow). The second image is a more detailed crop of the first, at full pixel level resolution.

click images to enlarge

The glare next to the tree in the wide field image, is due to a street lantern.

The satellite flaring to mag. +2.5 turns out to be Galaxy 11 (99-071A). It peaked near 22:18 UTC (23 May) and was visible with the naked eye at that moment, nothwithstanding it was low in the sky and I was observing from the city center.

The other object is Milstar 5 (02-001A) again. A faint trail of a non-geostationary satellite is visible as well: this turned out to be Globalstar 55 (99-049C).

Link: 2.2 MB animated GIF

Above link opens a 2.2 Mb animated gif with images from 22:10 to 22:19 UTC, which shows Galaxy 11 increasing in brightness. Milstar 5 is slowly drifting south.

A third geosat was captured on the images (not shown here), which is either Thuraya 2 (03-026A) or USA 202 (09-001A); probably the first.

Two naked eye flaring Geosynchronous sats

Dutch meteor observer Peter van Leuteren contacted me this week as he had a strange bright stationary object on images of his photographic all-sky meteor fireball camera, appearing in Ophiuchus at around 22:18 UTC on 3 consecutive nights. The same object was also noted visually, at mag. about +2.5, by BWGS chairman Bram Dorreman. It was evidently a brightly flaring geosynchonous satellite.

After an alert on Dutch and Belgian astronomy mailing lists, several observers noted it as well.

I took images last night (22 May, 22:13 - 22:25 UTC) in hopes of catching it and identifying it from the position. I used the Canon 450D with the EF 50/2.5 Macro for that purpose.

Unfortunately, as it later turned out, "the" mystery geosat (for now) was hidden just behind some tree branches for me. A few degrees west of it, I however captured a second flaring geosat!

That one has now been identified by Bram and me, based on my photographic positions, as Milstar 5 (2001-001A, #27168). I have made a movie out of 13 images (10 second exposures) spaced one minute each. It can be seen here (1.4 Mb animated GIF)

The FOV of the movie is a small crop from the images, at full pixel level. The object is moving southwards at about 55"/minute.

Volcanic dust effects at last! Bishop's Ring on May 18th

On May 17, a cloud of ash erupted from Iceland's now infamous Eyjafjallajökull volcano reached the North Sea area. It led to another temporary suspension of flights over the (western) Netherlands. And this time, there finally were clear visible effects in the sky as well!

The evening of May 17th stood out by being very hazy. Sunset colors were an unusual ochre (see photographs by Dutch KNMI meteorologist Jacob Kuiper here). But more excitedly, both Jacob and I managed to observe (and in my case, photograph) the rare Bishop's Ring.

Below image was taken by me on the late afternoon of May 18th, when remnants of the ash cloud passage still lingered in the atmosphere.

click image to enlarge

Visible is a diffuse disc of light around the sun (the sun itself is just behind the roof tip). The outer edges are reddish, the inner part is more bluish, as can be seen from this version where I depicted the RGB color values for two parts of the ring in the color spectrum:

click image to enlarge

With "normal" halo's, due to ice particles where refraction is the dispersal mechanism, the blue is on the outside and the red on the inside. Here however, it is the other way around, which confirms it is due to diffraction by dust.

An unidentified object

While reducing the remainder of my May 9-10 observations, I found what appears to be a UNID (unidentified object) on one of the images, close to eta Uma:

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It does not identify with any known catalogued object, or classified object known to us. The appearance is HEO-like (very short trail), it is present on only one (out of a series of five) images taken with the EF 100/2.5 Macro USM, and the trail looks to be part of a flare.

Most likely, it is a tumbling rocket stage of some past HEO launch.

-5 KeyHole flare! (May 9th observations, Part I)

Yesterday evening (9 May) I observed the most spectacular Keyhole flare I have ever seen. KH-12 USA 186 (05-042A) flared brilliantly to at least mag. -5 in a blue twilight sky, while crossing from Cvn into Uma. It yielded this Iridium-like picture:

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I cannot provide a brightness profile: for the simple reason that the trail is saturated over the full length. Peak time was about 20:34:29.4 UTC (9 May 2010).

I also observed on the 5th and 6th of May, capturing a.o. USA 186 again, as well as the IGS 5 r/b and the Molniya object USA 198.

USA 198 (07-060A) showed a clear, slow brightness variation over the 1m20s image series of 5 images, taken on May 5th, growing slowly fainter over the series:

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The data during the first 12 seconds of the diagram above, are close to saturation. Hence, the brightness variation in reality is probably more expontential than the diagram suggests.
The background readings have been taken just to the right of the trails, and are plotted to show that the change in brightness of USA 198 is not due to lens vignetting, but real.

Yet another nice USA 186 KeyHole flare

I am running behind with reporting on my observations again. After my last report, I observed again on the 22nd and 26th of April. Targets were the usual suspects: the KH-12 KeyHoles USA 129 and USA 186, and two of the IGS objects (IGS 1B, and the IGS 5 r/b).

USA 186 is giving nice flare shows again. On the 22nd, I captured one of these flares (peaking at 21:11:36.7 UTC) on photograph. The same image also has the Kosmos 1515 r/b on it as a stray. See the image below, and the brightness profile of the flare below it:

click images to enlarge

Another Keyhole flare

Although the skies were somewhat hazy, observations were conducted on the evenings of April 15th and 16th. Targets were the various IGS objects (1B, 5A, 5r/b), the Lacrosse 5 r/b, and the KH-12 Keyholes USA 129 and USA 186.

USA 186 was so friendly as to flare in my camera image on the 16th. The flare occurred at 20:43:40.75 UTC (Apr 16). Below is the image, and the resulting profile (with saturation at the peak). The two bright stars are the front stars of the pan of the Big Dipper, alpha and beta Uma.

click images to enlarge

Aircraft-less skies, but is the volcanic dust really visible?

Following the eruption of the Eyjafjallajoekull volcano of Iceland and the large amounts of dust it ejected into the atmosphere, airtraffic over NW Europe, including my country, has been completely halted. For four days now, this has resulted in unique airplane-less and contrail-less skies.

The sky is somewhat hazy for days here now, but is this due to the volcanic dust? Is it visible at all (as it was here after the 1991 Pinatubo eruption, causing pinkish-purple dusk skies)? Dutch news reports on Friday carried many photographs of red evening skies and red streaky clouds, purported to be the "volcanic dust". But all showed what to me looked like normal "evening red", sun-reddened cirrus clouds, and some even showed normal cumulonimbus!

I (and several Dutch astronomy and weather amateurs with me) have watched the evening skies the past days for anything unusual that could be attributed to the dust. But we failed to see anything more than what could very well be normal "evening red". Quite disappointing!

Below image was shot by me on Friday evening 16 April 2010 at about 18:29 UTC (20:29 CEST), some 10 minutes before sunset. Visible is a faint halo in the haze.

click image to enlarge

The orange is, in my opinion, normal evening red. And the halo: is it a "normal" halo in cirrus, or is it the "Ring of Bishop", due to dust?

The answer comes from a closer look. I have taken a part of the halo image, and increased the colour saturation to show the colour better. What can be seen (image below), is that the red/orange part of the spectrum is located at the inner side of the ring.

This means the ring is a halo in ice particles: in a dust-induced Bishop's ring, the red should be on the outside.

click image to enlarge

Satellite rush hour

Over the past week I could observe on the evenings of April 8th, 11th and 12th. Several objects were captured: the KH-12 USA 186 (05-042A) on all three evenings, IGS 1B (03-009B) on the 8th and 12th, the KH-12 USA 129 (96-072A) and the IGS 5r/b on the 8th. USA 186 slowly flared to -1 on the 11th at 20:34:45 UTC.

In addition, a number of strays were captured, including yet another Breeze-M tank (09-016C, from the Eutelsat W2A launch) and a non-classified military object, the DMSP B5D2-2 (83-113A) military weather satellite. The latter flared, with the flare peak near 20:34:12.87 UTC (secondary peaks near 20:34:12.45 and 20:34:13.37 UTC).

The DMSP flare was captured as a stray in a rather uniquely satellite-crowded image that also shows the KH-12 USA 186 (the target), the mentioned Breeze-M tank (09-016C), and a third stray, the Kosmos 1531 r/b (84-003B) all in an area of only a few degrees! Below is the image in question (the DMSP is moving from top to bottom here, USA from bottom to top):

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Below is the brightness profile of the DMSP flare derived from the image:

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During observations, I had a spectator: Pippi the cat followed my activities with close attention from behind the window:

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Spring objects, a Keyhole manoeuvre and a flare of the IGS 5 rocket

After three weeks with cloudy and rainy weather, two consecutive evenings on a row finally allowed observations again on 4 and 5 April.

This is the time of the year that, like spring birds, some object re-appear from their winter hiding: the American KH-12 Keyholes, and the Japanese Intelligence Gathering Satellites (IGS).

Two KH-12 keyhole optical reconnaissance satellites were targetted the past two evenings: USA 129 (96-072A) and USA 186 (05-042A). USA 129 is of special interest these days, as it made a small manoeuvre early april raising it's orbit slightly. I captured it 8 seconds late relative to an early April elset on April 4th. An analysis of the pre- and post-manoeuvre elsets suggest the manoeuvre occurred on April 1st near 04:35 UTC while the satellite was passing the US west coast just after going through it's ascending node.

USA 129 flared to mag. 0 on April 5th, 20:05:08 UTC.

Below is an image of USA 129 rising through patchy thin clouds in Leo on April 4th, and it's sister craft USA 186 moving low in the east though Bootes on the same evening around the same time:

click images to enlarge

I also got my first images of this year of the Japanese IGS, optical and radar satellites. The defunct IGS 1B (03-009B) was imaged on April 4 and 5, and flared briefly to mag. 0 at 21:21:15 UTC on April 5 with a distinct orange colour. On April 5, the IGS 5A craft (09-066A) was imaged by me for the first time.

Below is an image of IGS 1B shot on April 4th:

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I also captured the rocket from the 09-066 (IGS 5) launch: IGS 5r (09-066B). It shows flaring behaviour, as can be seen below from the photograph and the detail image, with the resulting brightness profile below that. The main brightness maximum in the image occurred at 21:44:06.9 UTC (April 5).

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Early March observations and pulsing (?) brightness of the STSS Demo-1

I am well behind on reporting on my March observations so far. I observed on the evenings of 1, 2, 3, 6, 7, 9 and 16 March. Observed objects include:

The Lacrosses 2, 3 and 5; NOSS 3-1; USA 200; USA 129; The USA 144 decoy; STSS demo 1 and demo 2; and a number of strays.

The KH-12 KeyHole USA 129 (96-072A) is a favourite target, now it has come out of it's winter hiding. I observed a number of flares from this satellite again (alas all while the camera was closed). Below are two trail images from 7 and 16 March, showing it rising (16 March) and decsending (7 March):

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The STSS Demo 1 & 2 objects (09-052A & B) were also frequently targetted. On March 16, I captured a shortlived pulsating brightness behaviour for STSS Demo 1 that is very similar to the shortlived pulsating behaviour I captured for the other STSS Demo object (demo 2) on February 20. Liek on that occasion, the behaviour is present in the first 2 seconds of one single trail image (out of a series of several). below is the image showing the pulses in the early part of the trail (top), and below that are the brightness diagram, and a diagram of the delta T between the pulses (read and compare also the report for February 20). The period for the early part is a flat 0.16s.

I do not want to exclude, even though I cannot explain it, that it is some instrumental effect. This because it is again in the first 2 seconds of a trail.

The Lacrosse 5 (05-016A) "disappearance trick": comparison of different occasions

Note added 13-11-2011:  visitors coming here through the link on Spaceweather.com, please read this story here first (click link) as there seem to be misunderstandings of what the video shows.


I am behind with reporting my observation activities over the last two weeks. Hereby a quick report however on one part of the observations: the Lacrosse/Onyx 5 (05-016A) SAR satellite.

Amongst the other Lacrosses (4 still in orbit, including Lacrosse 5) Lacrosse 5 is different in that it displays sudden and prominent brightness changes: from very bright (typically +1.5 or better) it goes to naked eye (near) invisibility, with a magnitude drop of at least some 3 magnitudes, in a matter of seconds. After that, it sometimes stays faint during the remainder of the pass: and sometimes it brightens up again after a while, sometimes followed by a second fading event.

This behaviour was coined the "disappearance trick" by me a few years ago. Although the earlier Lacrosses show some brightness variation as well, none shows it so clearly as Lacrosse 5, meaning something in the design of this satellite is different from its predecessors.

I have now been able to capture the satellite in the event of doing the "trick" three times: on 26 September 2009 during the BWGS meeting at Leo's place in Almere; and in the last two weeks on 24 February and 1 March 2010. The pictures and derived brightness profile of 26 September 2009 can be seen here: below are two pictures of the recent 24 February and 1 March observations.

click images to enlarge

The captured 24 February occasion was a case of Lacrosse 5 re-appearing and then disappearing again for a second time during the same pass.

I have combined the brightness profiles of all three events mentioned above into one comparison diagram. In all cases the curves are composites of 2 or 3 images taken during the pass in question (hence the non-continuous nature of the curves: the gaps are periods inbetween two pictures with no data recorded). The shown lines are 15-point averages to the pixel brightness along the trail.

click diagram to enlarge

It is clear from this comparison that the character of the brightness drop is not the same on all occasions. The 26 September 2009 event for example is more steep and sudden than the more gradual 24 February 2010 event. The 26 September 2009 event on the other hand compares relatively well to the 1 March 2010 event, the latter being perhaps slightly less steep.

Another thing notable is the suggestion of a omni-present brief shallow dip in brightness preceding the "disappearance" event by some 15 seconds (it can be seen near the 10 seconds mark in the diagram).

It is still difficult to make sense of this all. What are we seeing here? Is it a matter of strongly differing reflectance properties of the satellite body with illumination angle? Is it some brightly reflecting appendage on the satellite disappearing from view? Is it a dark appendage on the satellite starting to block view of the illuminated satellite body, or casting a shadow on it? Is it due to some moving part of the satellite, e.g. a moving dish antenna?

Phillip Masding has also probed the strange brightness behaviour of Lacrosse 5: his page with results is here and can be used as a comparison to the results I report above.

Chasing satellites through clouds and unusual brightness behaviour of the STSS Demo 2

The evening of Saturday-Sunday 20-21 February saw a very dynamic weather situation. Fields of clouds came and went very rapidly: the sky could go from clear to clouded to clear to clouded again in a matter of minutes. It made it a big gamble whether a particular object would eb visible or not.

As it came to be, I hauled a nice batch of positions on several objects: Lacrosse 5 (05-016A), the Lacrosse 5 r/b (05-016B), the STSS Demo 2 (09-052B) and the NOSS 3-2 (03-054A & C) duo. I also photographed the NOSS 3-4 duo but the image was too much hampered by cliuds tp reliably measure it. I lost amongst others Lacrosse 4 and the STSS Demo 1 to clouds (the latter a pitty, as it was predicted to pass right through the Pleiades).

Most of the images have some clouds on them: some extensively. Below are a few pictures: from top to bottom they show the Lacrosse 5 r/b amidst clouds; The NOSS 3-2 duo passing between the Pleiades and the Hyades; and the STSS Demo 2 passing near capella and the three Goats:

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The STSS Demo 2 appears to show an unusual brightness variation in the first 2 seconds of the trail (the left part of the trail in below negative image), consisting of what appear to be a series of even spaced modest glints. Note the dashed appearance of the first part of the trail:

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Below is the brightness profile over the trail (grey small crossmarks are individual pixel values, the solid line is a 3 point average), and below that is a graph of the time between brightness maxima visible in the profile.

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Note in the second diagram how the time between maxima is very constant, at about 0.13 seconds, during roughly the first 2 seconds . After that, it begins to wildly vary. As the first diagram shows, the amplitude of the brightness variations is larger in those first 2 seconds too. In fact, after those first two seconds the variation is largely or completely random pixel variation.

The first 2 seconds of the trail are quite different in character from the rest of the trail though: a clear constant, larger amplitude pulsing behaviour. This is very interesting. A second image obtained on the STSS Demo 2 during the same pass showed a quite constant brightness.