(UPDATED) Where are the observers? A map

Mid-June twilight starts very late, and generally I have not been observing the past 3 weeks due to that, as most interesting objects make passes well after midnight currently (and I need my sleep).

While exploring and practising with some simple GIS/mapping software I might start to use for my work, I made the map below. It shows you where the 20 most active observers regularly contributing position observations to satobs.org are located (the map was created with MicroDEM).

(click image to enlarge)

I also plotted my own two station positions on a combination of SRTM elevation data and a Landsat image. Cospar 4353 is my regular station and is in the centre of Leiden as you can see. My outpost station Cospar 4354 is in the polders to the east of Leiden, just south of the Rhine. (I exaggerated the relief by a factor 5 to better show the coastal dunes)

(click image to enlarge)

Clear nights, and the NOSS 3-4 rocket brightness behaviour

A series of clear nights the past week, allowing a series of observations of the STSS-ATRR rocket (09-023B) and two Keyholes, USA 186 (05-042A) and USA 161 (01-044A). 09-023B keeps being an interesting target, as its orbital evolution is that quick that it necessitates continuous coverage. The current orbit projects decay around mid-August.

About a week ago, on May 19-20th (see here), I obtained images on the NOSS 3-4 r (07-027B). This spent Centaur rocket of the NOSS 3-4 launch shows a slow brightness cycle. I obtained some partial brightness profiles from the trail photographs, including an interesting one covering one of the brightness peaks:

(click diagram to enlarge)

It can be clearly sees that this (10.05 s) part of the cycle consists of two components, a slow modestly exponential brightness development with a short narrow peak superimposed on it.

Flare evening

Yesterday evening 19-20 May was an evening of unpredicted flares.

It started with the International Space Station (ISS) in deep twilight. After a splendid zenith pass, while at 40 degrees altitude descending to the East, it shortly brightened to a dazzling mag. -8.

Somewhat later, still in twilight, it was the Keyhole USA 129 (96-072A) flaring to mag. 0. I caught one of the flares on photograph, just south-east of Regulus against a bright blue twilight background. Below the image ( plus a detail) and the brightness profile:

(click images to enlarge)

Somewhat later in the evening, I was next treated to a spectacular mag. -7 flare of IGS 1B (03-009B) while it was passing through the zenith, alas just after the camera shutter closed. The flare was a bright orange-yellow and lasted maybe a second (approximate time, not too accurate: 21:25:00 UTC).

Apart from these flaring objects, observations were also obtained of the NOSS 3-4 rocket (07-027B), showing its regular slow brightness variation; the keyhole USA 186 (05-042A), the SAR satellite Lacrosse 3 (97-064A) and the STSS-ATRR rocket (09-023B).

I also visually observed the STSS-ATRR itself (09-023A), but due to pressing a wrong button of the stopwatch lost my two points on it alas.

In all, a very fruitful night!

STSS-ATRR rocket again

Yesterday evening it cleared, and I observed the STSS-ATRR (09-023A) through the ETX-70, and photographically also its rocket (09-023B). In addition, I captured the KeyHole satellite USA 186 (05-042A).

The pass of the STSS-ATRR rocket (09-023B) provided the nice image below, showing it while crossing Lyra.

(click image to enlarge)

STSS-ATRR and it's rocket, and Progress-M66 (with photographs)

On May 5, the US military launched a Delta 2 rocket from Vandenberg AFB with the new experimental STSS-ATRR - which stands for Space Tracking and Surveillance System Advanced Technology Risk Reduction satellite. They are also known by the international designation 09-023A, and (for the rocket booster still circling earth) 09-023B.

European observers saw the satellite and the rocket as a thight pair shortly after launch, during their first pass over Europe (see e.g. here and here and here). While the payload was subsequently observed over more passes, the rocket initially got temporarily lost.

Ted Molczan suggested an alternative search orbit (here) and based on that I made an area search with the Meade ETX-70 on the evening of May 8-9, during 20 minutes (between 20:49 and 21:10 UTC) around the nominal pass time from that estimated orbit, covering a 4 degree wide area centered just south of gamma Umi and 11 Umi. During this search I observed an object of around magnitude +6 passing about 2 degrees south of the predicted trajectory, some 4 minutes late.

This indeed turned out to be the rocket. Independant from me, Bram Dorreman also observed it from Belgium that evening on the same pass, bumping into it by chance during his flash observations. With these observations as the basis for an orbital update, it was found and observed by several observers the following nights. Yesterday, in the evening of May 11-12, I photographed it (see below). During a fine zenith pass near 21:50 UTC it appeared as an easy naked-eye object, reaching mag. +2.5 in the zenith.

In below two (out of a total of 3) images it can be seen ascending in the south-southeast in Virgo, and then crossing Bootes in the second image.

(click images to enlarge)

That same night I observed the payload, STSS-ATRR itself, much fainter, with the ETX-70. In addition, I saw Progress-M66 (09-006A), recently released from the ISS, and ISS itself. below is one of the images of Progress-M66, here seen crossing through Leo.

(click image to enlarge)

The Misty 2 decoy, USA 129, IGS 1B and more

Yesterday evening was a very clear evening. A bright moon lit the sky though.

Several objects were imaged. Two Keyhole satellites were captured: USA 129 (96-072A) and USA 161 (01-044A). For the first time this year, the Japanese IGS 1B (03-009B) defunct radar satellite was in range again, always a sure sign spring has arrived. Below are two images, of USA 129 and IGS 1B.

(click images to enlarge)

Among the HEO objects, the SIGINT USA 200 (08-010A) and the USA 144 deb/Misty 2 decoy (99-028C) were captured.

The latter is an interesting object. Launched in May 1999, a bright object from the launch was tracked by amateur observers (see story here). After some time it became clear from the orbital behaviour of the object, that it could not be a real operational payload. Rather, it is a piece of debris or a decoy meant to draw attention away from the real stealth payload. The object is bright, but probably small and very lightweight, and moving in a 2700 x 3100 km orbit. Below is the image I obtained on a pass of this object last evening.

(click image to enlarge)

Keyhole USA 161 flaring

On the night of April 1-2, the Keyhole optical satellite USA 161 (01-044A) flared brightly to mag. -2 just after shadow exit. I shot a whole series of images (yielding 7 positions), of which this is the first (exposure starting a few seconds after flare maximum):

(click image to enlarge)

The same evening I also captured the Keyhole USA 129 (96-072A). HEO objects imaged were the SIGINT USA 200 (08-010A) and two brief glints by NOSS 2-3A (96-029A). The Russian Kosmos 2392 (02-037A) was captured as a stray on the USA 200 images.

Iranian Safir 2 r/b still slowly flaring

Yesterday evening, the atmosphere was very dynamic, with short clear spells repeatedly giving way to fields of clouds.

Nothwithstanding these conditions, I managed to image the Keyhole USA 129 (96-072A) again, plus the Iranian rocket booster Safir 2 r/b (09-004B) that launched OMID in February. I imaged it earlier in the morning of 7 March.

At that time, it showed bright flares in a slow pattern. It is still doing so, as yesterday evening's images show. The time between the bright glints is slightly less than it was early this month. I determined a 31.7 second interval between two of the glints, with glint times at (March 29 UTC):

19:57:19.5 UTC
19:57:51.2 UTC

On March 7, the determined glint interval was 33.25 seconds.

Below are the two images of last evening, plus the brightness curves. The glints appear to be slightly asymetric, with a slightly more shallow fall-off of the brightness after the glint maximum:

(click images to enlarge)

More HEO object observations

Yesterday afternoon I was very tired and fell a sleep on the couch. I woke up to find it clear outside, and the LEO observation window largely gone by already.

So a bit later in the evening I targetted some HEO (High Earth Orbit) objects again with the EF 100/2.8 Macro USM lens: USA 200 (08-010A) in a Molniya orbit, and the rocket booster USA198r (07-060B) in a 4.9 revolutions/day orbit.

The latter was at an altitude of 13 800 km (8625 miles) and a distance of 15 300 km (9560 miles) from me over the Kaspian Sea when I imaged it.

(click images to enlarge)

Nice pass of USA 129

The evening initially started clear. I observed the ISS, the Lacrosse 3 & 4 (97-064A & 00-047A) and the Keyhole USA 129 (96-072A).

Lacrosse 3 was very bright (+1) while descending to the west, showing multiple slow flares. USA 129 was very nice, +2.5 and grazing the tip of the Big Dipper's tail. It resulted in the nice picture below. The bright star grazed halfway by the trail is eta Uma, the tip of the Big dipper tail. Alcor and Mizar are in top. Movement is from righ to legt. The smudge at the left edge of the picture is clouds.

(click image to enlarge)

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)

The glinting behaviour of USA 32 (88-078A)

The year 2009 has started with a period of frost, and hence clear skies. I observed on January 6 and 9 and this evening (the 11th), catching a batch of objects: Lacrosse 3, USA 32, and various NOSS duo's.

The image of USA 32 (88-078A, a SIGINT satellite launched in September 1988) of this evening very nicely shows the glinting behaviour of this satellite. Along the trail, small bright dots (= very short glints) can be seen at regular intervals. They are indicated by the downward pointing arrows in the image (a 10.05 second exposure taken with my Canon EOS 450D and EF 50/2.5 Macro lens at F2.8):

(click image to enlarge)

Below is a brightness profile derived from the pixel brightness along the trail. The same peaks as indicated by the arrows in the photograph, show up well and are labelled A to H:

(click image to enlarge)

Analyzing the position of the glints, shows the following sequence:

1) a series of 4 or more glints at a regular 1.20 second interval;
2) followed by 2.0 seconds of no, or much less bright glints;
3) followed again by 4 or more glints at a regular 1.20 second interval.

Bright SKYMED 2 surprise

While waiting for USA 32 this evening, I was suprised by a bright object in a north-south trajectory majestically sailing through the zenith at 18:29 UTC. It was magnitude -2 for tens of seconds. I quickly re-aimed the camera and took this photograph:

(click image to enlarge)

On this photograph, where the object disappears behind the roof, it was already slightly less bright than only a few tens of seconds earlier.

It turned out to be SKYMED 2 (07-059A), an Italian Earth Observation Satellite launched a year ago on December 9th 2007.

Clear skies continue!

The series of clear frosty skies is continuing here. Following my last report on December 22nd observations, I have been able to do more observations on the 26nd, 27th and 29th, plus a number of deep-sky guided astrophotography sessions.

But first the satellites. Captured targets on these nights were Lacrosses 3 & 4 (97-064A & 00-047A), the NOSS 3-4 rocket (07-027B), which is still slowly variable, and the NOSS 3-2 duo (01-040A & C).

The latter NOSS duo made a very nice pass across the Pleiades yesterday evening:

(click image to enlarge)

Yesterday, I slao shot this photograph of the open star cluster M35 in Gemini. It is a stack of 65 x 10s images, taken with the Canon EOS 450D piggyback on my Meade ETX-70. Lens was the same EF 50/2.5 (at F2.8) I use for the satellite imagery, and ISO was set at 1200.

(click image to enlarge)

Near the edge of the original, M1, the Crab Nebula, actually shows up as well:

(click image to enlarge)

I used an image of the Pleiades shot the evening of the 25th to glean some more indications of the astrometric positional accuracy of the EF 50/2.5 lens. The stacked image contains several asteroids up to mag. +12 (10 Hygiea, 21 Lutetia, 94 Aurora, 182 Elsa and 264 Libussa), and by measuring these in Astrometrica (highly accurate astrometric software I use for my asteroid searches in NEAT data) and comparing to the predicted positions, it turns out that the positional deviations are typically within 5" (that is arcseconds).

That is the same accuracy AstroRecord (the wide field astrometry software I use for my satellite images) indicates from the fit to the reference stars. So it is the timing uncertainty which is the main cause of uncertainty in my satellite positions.