March 21 Iridium 33 flashes

Like yesterday and 4 days ago, I captured the Iridium 33 wreckage (97-051C) flashing again in a very regular pattern. Like the days before, the flash period was 4.66 seconds:

photo 1:

19:39:02.51
19:39:07.17
19:39:11.85

Photo 2:

19:39:44.46
19:39:49.13

Images with the flashes indicated by arrows below:

(click images to enlarge)

Very bright International Space Station (Updated)

This evening I observed a magnificent pass of the International Space Station (ISS), with the Shuttle docked to it.

At about 40 degrees altitude in the west, during its approach, it shortly became very bright. A conservative estimate by me placed it at at least magnitude -5; Leo Barhorst observing the same pass from Almere, some 30 km North of me, estimated magnitude -6. After that, it slightly fainted, remaining bright but not as bright as it had been in the west.

Update: telescopic images by Quintus Oostendorp on SpaceWeather.com show that the brightening was due to the solar panels reflecting sunlight.

This brief brightening was captured by my camera. The Hyades are visible to the left, the Pleiades to the right.

(click image to enlarge)

More flashing Iridium 33 wreckage, ISS, USA 200 and other high objects

As I wrote in my previous post with the image of USA 129 flaring, yesterday evening I hauled a rich batch of objects.

It started in twilight with a nice pass of the International Space Station (ISS). The image below shows it rising through Orion:

(click image to enlarge)

Next I photographed passes of Lacrosse 3 (97-064A) and the NOSS 3-4 rocket (07-027B).

The wreckage of Iridium 33 (97-051C) was observed flashing again. Two photographs yielded five flashes, and like 3 days ago they fit a flash periodicity of 4.6 to 4.7 seconds. The timings were derived by measuring the flash positions astrometrically, and fitting the obtained positions to the most recent Iridium 33 tle. Here are the two images, with the flashes indicated:

(click images to enlarge)

I also targeted some HEO (High Earth Orbit) objects again, this time experimenting with different camera settings. USA 200 (08-010A) was captured again, this time somewhat better than 3 days ago:

(click image to enlarge)

I combined 4 of the images into an animated GIF, showing the movement of the sky and the satellite over a 1 minute period:



On the same image series I captured a piece of debris, USA 144 debris (99-028C), as a stray. In addition, I imaged another object in a Molniya orbit, USA 179 (04-034A) and the USA 198 rocket (07-060B) this evening.

USA 129 flaring

This evening I bagged a rich bag of objects. Amongst them was the Keyhole satellite USA 129 (96-072A), that treated me on a bright mag. -1 flare at 20;24:25 UTC (March 20) shortly after emerging from eclipse in Perseus. I captured the peak and descending brightness part on the image shown below.

(click image to enlarge)

The light-curve is saturated near it's peak:

(click image to enlarge)

Imaging distant objects: USA 200

Recently, I bought a new lens for my camera: a Canon EF 100/2.8 Macro USM. As this lens has a larger diameter than the EF 50/2.5 Macro I use for my regular satellite imagery, it is able to capture fainter stellar objects. Of course, the Field of View (FOV) is half as small, which makes it less fit for imaging objects in LEO (Low Earth Orbit).

It is more suitable though for imaging distant objects in HEO (High Earth Orbit): satellites which are at thousands of kilometers altitude (including, but not restricted to, Geostationary satellites). The brightest of these are around magnitude +8.5.

Yesterday I did some first succesful experiments on one of those objects: USA 200 (08-010A, NROL 28), an NRO ELINT satellite launched on 13 March 2008. It is in a Molniya orbit and as I imaged it, it was at an altitude of 29 564 km above the earth, and a distance to me of about 29 920 km! Hovering (well: not really. It is slowly moving in its orbit) high over Iceland at that moment, it keeps a watchful signals eye over the northern Atlantic and arctic.

I shot a series of 20 second exposures, from stationary tripod. The satellite showed some movement during these exposures. below photograph shows one of the images: the satellite has made a faint short trail perpendicular to the star trails.

(click image to enlarge)

The images below show the orbit of USA 200. The Molniya-type orbit means it orbits about twice a day, spending only little time in its perigee at low altitude over the southern hemisphere, and most of its time in the hight altitude parts of its orbit over the high northern hemisphere, its surveillance area.

(click images to enlarge)

More flashes from the Iridium 33 wreckage

Yesterday evening, after observing the exciting ISS-Shuttle duo pass (see previous post), I tried to observe flashes from the Iridium 33 wreckage (97-051C) again. Simone had provided some experimental predictions and asked for verification.

The Iridium 33 wreckage did flare: two very bright flashes (both around mag. -1) seen naked eye, and two fainter ones (+4?) found on a photograph. They were off from the experimental predictions, but still cool!

The two -1 naked eye flashed were observed at 17 March, 20:06:56 ± 1s and 20:07:02 ± 5sUTC. The two photographic fainter flashes/glints occurred at 20:07:15.7 and 20:07:20.4 UTC. The time between the latter two is 4.7 seconds, and the first two (the naked eye ones) within their timing uncertainties fit a similar 4.7 second period.

The image with the two faint photographic flashes is below:

(click image to enlarge)

Magnificent view of Shuttle and ISS just before docking!

I had a pass of the Space Shuttle Discovery STS-119 and the ISS this evening about one hour before they docked. This meant they were moving as a very close pair. The pass was around 19:10 UTC at 25 degrees altitude.

It was a beautiful sight, as the pair rose in the southwest and then majestically sailed past Sirius. Here's a picture:

(click image to enlarge)

The Shuttle is the object slightly fainter and lower in the sky. Movement is from right to left. Here's a second picture:

(click image to enlarge)

Iridium 33 wreckage photographed, with +4 glint

This evening was quite clear, and I decided to employ my new Canon EF 100/2.8 USM Macro lens to image a pass of the Iridium 33 main wreckage (97-051C). This lens has a bigger aperture than the EF 50/2.5 Marco I normally use, and hence is better for faint objects.

I was lucky and not only captured the very faint, irregular trail of the Iridium 33 wreckage: but also a short glint to mag. +4 at about 19:29:51 UTC (15 March), which I also observed with the naked eye.

The image is below. The inset shows the short glint, close to the end of the trail.

(click image to enlarge)

A close call for the ISS

Shortly after the collision of Iridium 33 and Kosmos 2251, the news agencies are buzzing with a close call of the International Space Station and a piece of space debris. Astro/Kosmonauts in the station shortly evacuated to their Soyuz re-entry capsule for safety reasons.

The piece of space debris in question was 93-032D (25090), a piece of a PAM-D rocket engine, part of the launch of the Navstar 32 GPS satellite on 13 May 1993. It is small, but even small can be lethal to the ISS. The nominal orbits for the ISS and the space debris piece have it pass as close as within 2.4 km of each other at 12 March, 16:39:41 UTC. The close encounter occurred over the southern Atlantic, near the southernwest coast of Africa.

(click images to enlarge)

Iridium 33 and Kosmos 2251 wreckages observed

I visually observed the main wrecks of both Iridium 33 and Kosmos 2251 with the Meade ETX-70 (7 cm F5 refractor) this evening.

The Iridium 33 wreckage (24946, 97-051C) was easy to see and notably irregular in brightness, with many short flashes (several per second, with a brighter one approximately each second. This is an estimate: I did not time them). I observed it as it passed close to Pollux near 19:55:10 UTC (11 March). At its brightest it might have been +6 or +6.5. I did not observe the kind of bright flares as reported by Simone from Italy yesterday.

The Kosmos 2251 wreckage (22675, 93-036A) was much fainter, about +8 at its brightest as it passed close to alpha Uma at 20:11:30 UTC. It too was irregular, but its brightness variation seemed slightly slower than that of the Iridium 33 wreckage.

I also observed Lacrosse 3 in twilight and got 6 positions on it.

An Iranian rocket (Safir 2 r/b)

Weather finally allowed me to observe one of the new Iranian objects from the February 2nd launch. It concerned the rocket booster from the launch, the Safir 2 r/b (09-004B).

Conditions were not perfect (somewhat hazy), but the rocket booster was well visible and I captured it on two images (see below). It showed a clear very slow amplitude brightness variation (amplitude >20 seconds), going between mag. +3 and near-invisibility for the naked eye (> +4). Around the brightness peak it gives a short bright glint. Both my photographs captured such a glint.

(update) Based on the two pictures, and assuming I didn't miss a glint in between them, the glint period is 33.25 seconds, with glints at:

7 Mar 2009 04:26:12.60 UTC
7 Mar 2009 04:26:45.85 UTC

Below the two pictures (as usual, Canon EOS 450D @ 800 ISO + EF 50/2.5 Macro @ F2.8), and the brightness profiles for these trails.

(click images to enlarge)

Lacrosse 5 passing alpha Persei

Earlier this week, on February the 24th, the generally very bad weather of this moment gave way to a short period of clear skies after dusk. This allowed me to obtain some positions on the bright SAR satellite Lacrosse 5 (05-016A) and it's spent rocket booster Lacrosse 5r (05-016B).

Below is an image showing Lacrosse 5 passing close to alpha Persei and the alpha Persei star association.

(click image to enlarge)

Comet C/2007 N3 Lulin from Leiden

The weather is horrible these days, so I was much surprised by short clearings developing around local midnight last night. These allowed me a short peek and photo session on comet C/2007 N3 Lulin.

In the ETX-70 (small 7 cm refractor) at 14x, visually the comet was a nice fuzzy ball with a tail in NW-SE direction. Easy to find, especially as it was only a few degrees from Saturn.

I had only a short window of opportunity to photograph the comet before clouds came in again. Below image is a stack of 24 x 10 second exposures, made with the Canon EOS 450D (@800 ISO) and EF 50/2.5 Macro lesn (@ F2.8) between 23:18 and 23:26 UTC (23 feb).

Note that the conditions were far from perfect: not the best of skies, the comet low in the sky (35 degrees), and in the middle of Leiden town! So I am happy with the result.

(click image to enlarge)

Aftermath of a space collision

Over 200 fragments of the Feb 10th collision between Kosmos 2251 and Iridium 33 have now been catalogued. Together, they form two impressive orbital planes filled with debris. The amount of Kosmos 2251 debris catalogued so far is about twice as large as that for Iridium 33 - it seems the Kosmos took the most serious blow.

Most of this debris will stay up for tens of years. About 6% of the Kosmos and 3% of the Iridium debris will decay in the next 2.7 years.

(click images to enlarge)

Feb 15 Texas-Nebraska daylight fireball was NOT satellite debris

Sightings of a bright daylight fireball seen from Texas to Nebraska on February 15th, have been widely reported in the press.

Contrary to what the FAA appears to be stating, this was definitely NOT debris from the collision between the Iridium 33 and Kosmos 2251 satellites on February 10th.

Video footage of the fireball (see below) shows that it moved clearly too fast for that, and was of too short duration, to be decaying satellite debris. In stead it is in line with a meteoritic fireball (asteroidal debris).

There is a clear difference in speed between the two categories: asteroidal/cometary debris moves at at least 11 km/s (and usually much faster) and typically lasts only a few seconds (as this fireball did). Satellite debris decaying moves at 7.5 to 8 km/s, so clearly slower, and typically has a much longer duration (due to the slower speed, but also because it enters at shallow angles). The video footage is incompatible with the appearance of decaying satellite debris. It is completely compatible with a meteoric fireball (asteroidal debris).

In Memoriam: Iridium 33

On 10 February 2009 at 16:56:00 UTC, Iridium 33 (97-051C) collided in orbit with the defunct Russian Kosmos 2251 satellite (93-036A). The collision occurred at 789 km altitude over the Siberian arctic, near 97.9 E, 72.5 N, with an orbital interception angle of 83.5 degrees. A cloud of rapidly spreading debris is now all that remains.

The collision occured at roughly the same altitude as the Chinese ASAT test on Fengyun 1C, and the resulting scenario for the debris cloud will be roughly similar to the latter event. An analysis of the Fengyun 1C debris field formation by Kelso can be read here.

On May 18th 2007, when Iridium 33 was still happy, alive and flaring, I shot the picture below:

(click image to enlarge)

Observed the flying toolbag

This evening it was clear. Besides photographing the passes of Lacrosse 4 (00-047A) and the NOSS 3-1 duo (01-040A & C), I watched a nice ISS pass together with my neighbour and for the very first time also managed to see the ISS tool bag (98 067BL), the bag with tools lost in space by an astronaut during an ISS EVA in november 2008.

The latter observation was made with my Meade ETX-70 (7 cm refractor) at 13.5x magnification (field-of-view about 4 degrees) during a near-zenith pass at 18:03 UTC (27 Jan), when the object passed close to Algol.

It was faint (mag. +7 to +8) and very fast, zipping through the field of view being gone before you knew it. I had some impression of a slow brightness variation.

It was very nice to finally see it, after a few earlier failed attempts.

Video of the astronaut loosing the toolbag....

My third Trojan asteroid

As the weather did not allow observations the past week, some news from my asteroid searches. Whenever I want something to do in the evening and it is clouded (so I can't observe satellites) and the TV is dull -which it usually is-, I turn to hunting for new uncatalogued asteroids in NEAT archive imagery.

Today's DOU MPEC 2009-B61 contains four of my new asteroid finds of last week. One of these, 2002 WG29, is a Jovian Trojan, my third Trojan discovery (the other two are 2001 SD355 and (203865) = 2002 WV27).

Jovian Trojans are asteroids that co-orbit with Jupiter in a 1:1 mean motion resonance, as they occupy the stable Lagrange points L4 and L5 in the Jupiter orbit. They are hence a quite special class of asteroids. Currently, some 2900 of these Trojans (including those with temporary designations) have been discovered. Their positions for late 2008 in the two Lagrange points at 60 degrees in front and behind of Jupiter are shown below:





Among the other discoveries of last week are two Hungaria asteroids. Hungaria asteroids are a special class as well: they occupy higher inclinations within 2.0 AU, a region in the main asteroid belt where at lower inclinations a stable orbit isn't possible due to perturbations by Mars. Hungaria's move in a 9:2 mean motion resonance with Jupiter and a 3:2 mean motion resonance with Mars. Hence, they quite stand out among the main belt asteroid population.

Below are two plots showing the positions in the solar system of the objects I discovered for coming February 1st. The new Trojan is the one currently just outside Jupiter's orbit in the top plot.

A full list of my asteroid discoveries can be found here.

(click images to enlarge)

Lacrosse 3 and Uranus

This evening it unexpectedly cleared. I photographed the only available pass of Lacrosse 3 (97-064A) to clearify whether it was still on-time. It was: I obtained two points with delta t resp. 0.03 and -0.08s and delta positions 0.019 and 0.039 degree respectively.

The pass was a very low pass however, the satellite did not come higher than 25 degrees in the sky. This made it difficult, and I only managed to capture it on two images when the satellite was just above rooftop level, in a "gap" between two roofs. On the first image it appears from behind the roof (endpoint measurable), on the second it disappears behind the roof (startpoint measurable).

When astrometrically measuring the images, I noted a relatively bright star near the end of the trail that I could not identify. It was also on the 2nd image. The star was bright enough that it should appear in the database AstroRecord uses, and my Sky Atlas didn't show a star there either. So...?

As I was measuring the image anyway, I decided to measure the star to get a position for it. it yielded (18 Jan 2009, 17:49:12.3 UTC):

RA 350.855, dec -4.751
= 23h 23m 25.2s, -4 45' 03.6" (2000.0)

I checked AstPlot: it did not show a star nor an asteroid on that position. I downloaded a NEAT image of the region: again, no star on that position....

By that time, I was thinking: Oi, what's this?!? A nova?!?

Then I got a hunch. I started up MICA, and obtained accurate positions for Uranus and Neptune. And yes, there it was:

Uranus
Astrometric Positions Mean Equator and Equinox of J2000.0

Date Time RA Declination
h m s h m s ° ' "
2009 Jan 18 17:49:12.3 23 23 24.115 - 4 45 03.16

So, I accidently "re-discovered" Uranus... 228 years too late... :-p

A reduced resolution crop from one of the images is below, with objects annotated:

(click image to enlarge)

NOSS 3-4 duo through Perseus

An initially very clear evening today allowed observations again. Lacrosse 3 (97-064A) was captured, along with NOSS 2-3D (96-029D) and the NOSS 3-4 duo (07-027A & C). USA 32 (88-078A) was captured as a very faint trail but not measured.

A mistake of one minute in the timing while trying to photograph the 96-029 objects made me miss the C & E objects, but captured the D object at the end of what seems to be a slow flare.

One of the images of the NOSS 3-4 duo, the one where they cross Perseus just below the alpha Persei star association, turned out particularly nice, with lots of stars and two bright trails:

(click image to enlarge)