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.

More on Monday evening

Below is a second astrophotography image I made last Monday evening (see previous post). It shows M31, the Andromeda Galaxy. The image is the result of stacking 100 images of 10s exposure each, made with my Canon EOS 450D + EF 50/2.5 Macro piggyback on my ETX-70.

(click image to enlarge)

A very clear night, Lacrosses, the Breeze-M tank and the Pleiades

Yesterday evening (22 Dec) was very clear. I obtained photographs of the passes of the Lacrosse 5 rocket (05-016B), and Lacrosse 4 (00-047A)..

I photographed Lacrosse 4 with the Pleiades just before eclipse (see below). When inspecting the image for astrometric reduction, I noted a second, fainter trail on the image. Measuring it and running an ID, I found it was close to predicted positions for the Breeze-M (deb) tank, 05-019C. There was an odd 0.6 degree discrepancy though. Mike solved it by pointing out that a SDP4 solution yielded perfect residues, while the SGP4 theory SatFit uses doesn't. So, the question mark plus the "UNID" in below image can be erased.

(click image to enlarge)

Later that night, after the LEO window closed, I spent some time doing astrophotography with my camera piggyback on my Meade ETX-70. I still have to stack part of the images, but already finished stacking 102 x 10s exposures of the Pleiades with the EF 50/2.5 lens, yielding this result:

(click image to enlarge)

Short observing session

Saturday evening saw a short break in the bad weather, and some clear sky. A slight haze and near full moon made the conditions not too excellent, but I managed to catch positions on Lacrosse 5 (05-016A) and the NOSS 3-2 duo (03-054A & C).

Below is a picture of the latter crossing near Polaris.

(click image to enlarge)

Bad weather

Bad weather and midwinter situations leading to only a very short observation window right after dusk are the main reasons why observing has come to a stop at the moment. I haven't been able to observe since November 29th, which itself was preceded by a period of forced non-observation due to the weather.

This means I spent some time hunting asteroids again in archive imagery of the NEAT project. It was (and is) a rather prolific stint of asteroid hunting, yielding the following new designations (with a few datasets still pending):

tmp. desig.
2002 PN188
2002 WQ27
2001 SD355
2002 WR27
2002 XK118
2002 UU76
2002 WV27
2002 WW27
2002 WX27

For a complete list of my discoveries, see here.

Two of the new discoveries (2001 SD355 and 2002 WV27) are Jovian Trojans moving in the L4 and L5 Lagrange points of Jupiter, 60 degrees on either side of it, sharing the planet's orbit. It are my first trojan discoveries.

In total I now discovered one Near Earth Asteroid (in the Spacewatch FMO program) and (in the NEAT archives) two Trojans and 22 main belt asteroids.

Space Shuttle STS-126

After a very long period of poor weather, this evening was clear enough to see some stars and...Space Shuttle Endeavour STS-126. The sky quality was poor though, with a lot of haze.

The first observation was in deep twilight, at 16:25 UTC. STS-126 was 1m 45s ahead of ISS, descending to the east as the ISS rose in the west. It was bright, at least -1.5. I captured both on a series of 4 second images. Below is a composite of two of these images, taken 1m45s apart and combined in to one picture:

(click image to enlarge)

The second pass was at 17:58 UTC, when it was completely dark. Both STS-126 and the ISS disappeared in the Earth shadow at 50 degree altitude. The Shuttle was very bright, at least mag. -2. Below are two images: one single shot of the Shuttle, and a second where this image is combined with a shot of the ISS taken 1m 50s later. One can see from the latter, that STS-126 was almost as bright as the ISS:

(click images to enlarge)

I also captured Lacrosse 2 (91-017A), which manoeuvred a few days ago, on photograph. To my surprise, as I failed to see it naked eye, I also have Progress-M65 faintly on photograph.

Asteroid (142014) Neirinck

Today, it was my pleasure to announce to Pierre Neirinck that the IAU has approved this new asteroid name:

(142014) Neirinck

The naming citation published in the Minor Planet Circulars, reads:

(142014) Neirinck = 2002 PA168 Discovered 2002 Aug. 8 by NEAT at Palomar.
French-born Pierre Neirinck (b. 1926) headed the Satellite Orbits Group at Appleton Laboratory in the U.K. during the 1970s. Now retired, he still coordinates the international amateur satellite observations. The name was suggested by M. Langbroek.

Pierre Neirinck is a veteran satellite observer and analyst. As an active French observer from the dawn of the space age, he was recruited by the British satellite research analyst Hele-King, and headed the British Orbital Analysis Group from the early seventies until his early retirement. Now 82 years old, he still actively observes, and coordinates amateur satellite observations. He provides new Cospar designations to new observers, and daily sends bulletins updating the orbits of some of the more interesting satellites (notably the KeyHoles). His daily reports are a delight to read, not only because of the orbit analysis, but also because they always contain an ironic, sometimes even cynic commentary on current affairs in this world. Amongst others, he keeps a dedicated tally of the number of people that depart our planet in violent ways each day.

(142014) Neirinck was discovered by me in archived images of the NEAT project from 8 August 2002 (and surrounding nights) taken by the 1.2 meter Schmidt telescope of the project at Mount Palomar. With H=16.9, it is estimated to be about 1.5 kilometers in diameter. It completes an orbit around the sun each 3.8 years.

(click image to enlarge)

The same batch of MPC's contained three other new asteroid names suggested by me for objects I discovered:

(132820) Miskotte

132820 Miskotte Discovered 2002 Aug. 17 by NEAT at Palomar.
Koen Miskotte (b. 1962) is a Dutch confectioner and amateur astronomer whose main interests lie in meteor astronomy. He is a very prolific meteor observer, active within the Dutch Meteor Society. The name was suggested by M. Langbroek.

Koen is a very close friend of mine, and we have travelled the world and observed meteor showers together many times. He is a dedicated, extremely active meteor observer for many decades now, and has contributed data to several scientific meteor studies.

(179678) Rietmeijer

179678 Rietmeijer Discovered 2002 Aug. 26 by NEAT at Palomar.
Frans J.M. Rietmeijer (b. 1949) is a Dutch-born planetary geologist specializing on interplanetary dust particles. He is a research professor at the University of New Mexico. The name was suggested by M. Langbroek.

Frans, a renowned expert scientist on IDP's, is a close friend too, even though he lives at distance in New Mexico. We met 10 years ago through my meteor/meteorite related activities and soon developed a personal friendship. Whenever Frans is briefly in the Netherlands again we meet for a dinner. He has acted as my older & wiser mentor in science career related business.

(132798) Kürti

132798 Kürti Discovered 2002 Aug. 8 by NEAT at Palomar.
Stefan Kürti (b. 1960) is a Slovakian amateur astronomer with a focus on minor planets. Among his discoveries are two near-earth objects. The name was suggested by M. Langbroek.

Stefan was in the Spacewatch FMO project with me, and is an active asteroid hunter. He surprised me last summer by naming one of his finds after me.

A decaying tank that is not shot down

Somewhere today, the Early Ammonia Servicer (EAS) will plunge into our atmosphere and decay. The EAS is a large refridgerator-sized tank filled with ammonia, that once was part of the International Space Station. It was never used, and finaly jettisoned during an EVA on July 27th, 2007. I observed it several times, and photographed it on July 20 this year.

Interestingly, some pieces of the EAS are thought to probably survive re-entry. Plus, it is filled with a large amount of Ammonia, a rather agressive substance.

Remember all the fuss about the hydrazine tank of USA 193 early this year? The danger of anyone coming into contact with the agressive hydrazine, was the official "argument" to shoot the decaying spy satellite USA 193 down with a missile. Subsequently, fierce debate erupted about whether this really was the reason or not (see here and here).

Now, here we have another tank with an agressive substance, the EAS, decaying. And does anyone really bother? No, apparently. Even though a NASA spokesperson is quoted in this Space.com story as saying:

NASA expects up to 15 pieces of the tank to survive the searing hot temperatures of re-entry, ranging in size from about 1.4 ounces (40 grams) to nearly 40 pounds (17.5 kg).

and:

"If anybody found a piece of anything on the ground Monday morning, I would hope they wouldn't get too close to it," Suffredini said.

Wasn't the last thing exactly what all the hu-ha was about with USA 193?! I again conclude that the whole fuss about the hydrazine in USA 193 was not the primary reason to shoot it down....

(Click image to enlarge)

Goodbye ATV-1

The ATV-1 "Jules Verne", Europe's first cargo craft to the ISS, was de-orbited over the Pacific today. The past weeks it flew solitary, for experiments. Last Thursday I could see it for a last time, and I shot this picture of it:

(click image to enlarge)

Short observing break (partly due to camera defect)

Short observing break here. Several reasons: apart from it being overcast the past three days, it includes that;

- I am working on a double lecture (Friday on my own university, next week in York);
- and am having to deal with a camera defect.

The camera defect is small but fatal for shooting the night sky: for some reason (loose electronic contact?) the wire-release no longer works when the camera is pointed upwards....

So if I am able to observe early next week and after I return from York, it will probably be the good old visual way with the ETX-70 telescope and stopwatch for a while.