Tuesday, 30 December 2008

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.

Wednesday, 24 December 2008

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)

Tuesday, 23 December 2008

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)

Monday, 15 December 2008

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)

Wednesday, 10 December 2008

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.

Saturday, 29 November 2008

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.

Tuesday, 18 November 2008

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.

Monday, 3 November 2008

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)

Monday, 29 September 2008

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)

Wednesday, 24 September 2008

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.

Sunday, 14 September 2008

Rich batch of objects

The night of 13-14 September was a very clear one. The near-full moon was low in the sky and the sky very transparent.

I hauled a rich batch of objects, including 8 positions on the KeyHole USA 129 (96-072A), the Lacrosses 4 & 5, (00-047A & 05-016A), and the NOSS duo's 3-1 and 3-2 (01-040 A & C, 03-054 A & C).

USA 129 made a magnitude 0 flare at 20:19:20 UTC. The descending part of the flare was captured on photograph.

(click images to enlarge)




Monday, 8 September 2008

Andromeda Galaxy

Finally came to process some images I made after my satellite observing session of September 1st. Stacking 58 images with an exposure time of 15 seconds each, resulted in the image of M31, the Andromeda Galaxy, below. The camera (Canon EOS 450D @ 800 ISO) was mounted "piggyback" on my small Meade ETX-70, the lens was the EF 50/2.5 Macro @ F2.8 which I also use for the satellite pictures.

(click image to enlarge)

Saturday, 6 September 2008

Flares, strays and spy sats

The evenings of September 1st and 3rd saw a nice catch of satellites. My new camera system (Canon EOS 450D + EF 50/2.5 Macro) really is a sat magnet, which is also apparent by the number of strays captured in images with classified objects.

Objects imaged these nights include the KeyHole satellites USA 129 (96-072A) and USA 186 (05-042A), the SAR sats Lacrosse 4 & 5 (00-047A and 05-016A), and the Japanese sats IGS 1A and IGS 1B (03-009A and 03-009B).

IGS 1A is an example of a sat that would normally be beyond reach of my older camera system, but is well within reach now. The KeyHoles are captured much more easily now too.

Moreover, the quality of the positions obtained seems to be better. This is due to both the better image quality (less ambiguity in the start and end of the trails, as the images are much less noisy and the trails brighter), and to a much better, consistent timing behaviour of this camera.

Because of the more narrow field of the EF 50/2.5 Macro lens, I employ the laser (the same I use for pointing my telescope) to point the camera. Below is a photograph of what this looks like (although in reality the beam is less bright visually: this is the result of a 10 second exposure). Stars visible are from Cassiopeia and Perseus, with the double cluster visible just beneath the laser beam.

(click image to enlarge)



On September 1st, I watched Lacrosse 5 (05-016A) together with my neighbour. It was nice and bright, and did it's infamous "disappearance trick" while just past the zenith. I had just been explaining this peculiar behaviour to my neighbour, so he got a nice demonstration!

Some nice flares were captured too these evenings. Below images show a mag. -8 flare of Iridium 72 on 3 Sep 20:15:29 UTC, and a brief mag 0 flare/glint by KeyHole satellite USA 129 (96-072A) at 20:33:34 UTC on the same evening. The curtain-like structure on the Iridium image is due to a moving patch of clouds.

(click images to enlarge)




Several strays were captured as well, mostly spent Russian rocket boosters.

Sunday, 31 August 2008

Purple volcanic twilights, and KeyHole satellites

Last Friday evening was clear again. Looking outside in twilight, I noted the sky was amazingly purple, due to volcanic aerosols spewn by the Kasatochi volcano in the Aleutians. I walked a few blocks to the Witte Singel canal and shot this picture, with one of the domes of Leiden Observatory silhoutetted in the far distance:

(click image to enlarge)



Later that evening, I captured two Keyholes, USA 129 (96-072A) and USA 186 (05-042A), the Japanese satellite IGS 1A which made a small manoeuvre recently, and a very fine mag -3 flare by Iridium 65. Unfortunately, clouds came in later in the evening.

(click image to enlarge)

Sunday, 24 August 2008

Asteroid 183294 Langbroek!

This weekend, I got notified of the fact that the Committee on mall Body Nomenclature of the International Astronomical Union (IAU) has decided that asteroid 183294 (also know by its temporary designation 2002 TB382) will henceforth be officially named:

183294 Langbroek

The citation text from Minor Planet Circular # 63643:

(183294) Langbroek = 2002 TB382
Discovered 2002 Oct. 9 by NEAT at Palomar.
Marco Langbroek (b. 1970) is a Dutch archeologist and amateur astronomer whose main interests lie in meteor astronomy. He is an avid meteor observer, active within the Dutch Meteor Society. The name was suggested by S. Kürti.

Asteroid 183294 Langbroek is a main belt asteroid with an estimated 2.5 km diameter (H 15.6), has it's perihelion at 2.69 AU, aphelion at 3.39 AU and an orbital inclination of 6.34 degrees. It revolves around the sun once each 5.3 years, between the orbits of Mars and Jupiter. It was discovered on images taken 9 October 2002 with the 1.2 meter Schmidt telescope of the NEAT program at Mt. Palomar.

I feel very honoured by this asteroid naming.

Here's a blink of the discovery triplet, made on 9 Oktober 2002 with the NEAT 1.2m Schmidt telescope at Mt. Palomar:



Below is a plot of the orbit:

(click image to enlarge)


For an interactive orbit plot (JPL website), click here.

Lacrosses and a very fine USA 161 flare

Coming back from a date shortly after midnight of August 23-24, I noted it was very clear, with only occasional small cloud fields passing. This allowed me to photographically target the optical imaging Keyhole satellite USA 161 (01-044A) and the radar Lacrosses 4 & 5 (00-047A & 05-016A).

USA 161 briefly brightened in Cassiopia, featuring a very short mag. 0 flare at 23:44:09 UTC. I was so lucky to have the camera open at that time, resulting in this very fine flare picture (with below it, the brightness profile):

(click images to enlarge)


Friday, 22 August 2008

More on the USA 193 shootdown

The online Bulletin of the Atomic Scientists has published an essay by Harvard astrophysicist Yousaf Butt with a very critical view of the official reasons given for the USA 193 shootdown.

Butt filled a request through the Freedom of Information Act and obtained the report featuring the re-entry model and analysis that was used. And found it to be flawed and on closer look not quite supportive of the alledged 'danger' of the re-entry of USA 193's hydrazine fuel tank.

The report is very cautious and it's authors already note that some of the model assumptions are not realistic. Importantly, it shows that even with these assumptions maintained, much of the tank's titanium outer layer will ablate according to the model (remember how Oberg denied this in his essay?!), leaving only a very thin outer shell 1/5th or less of the original thickness. This assumes uniform ablation (which is not realistic).

Butt argues that when more realistic assumptions are made, this suggests the tank would likely have been destroyed upon reentry.

You can read the essay here, and it includes a link to the report pdf.

The essay highlights:

  • A NASA study on the survivability of USA-193's hydrazine fuel tank used an oversimplified model, leading to an overly optimistic assessment of the tank's survival.
  • But even this study showed how the tank would have burned up when reentering the atmosphere.
  • Therefore, Washington's contention that the tank would have hit the ground intact, posing a health hazard, seems questionable.
Another thing to note is that the tank was not completely filled with fuel, but 76% filled. This turns out to be of importance in assessing the fate of the tank.


(with thanks to John Locker for te 'heads up')

Wednesday, 20 August 2008

IGS 1B and NOSS 3-2 amidst flying clouds

Yesterday evening the atmosphere was very dynamic, with flying clouds. I did manage to capture the NOSS 3-2 pair (03-054A & C) in twilight, and IGS 1B (03-009B). The NOSS image suffered from twilight and clouds, but also yielded a fast stray (which I still have to identify).

IGS 1B was very bright again (+0.5) when it came out of eclipse and passed almost overhead. The picture below gives a good indication of the observing conditions.

(click image to enlarge)

Sunday, 17 August 2008

Keyhole USA 186 manoeuvred at Aug 14.6, and imaging a NOSS duo (REVISED)

A late report on my August 14 observations and associated topics.

August 14 featured a nice clear evening. I captured the Keyhole USA 186 (05-042A), the Japanese failed radar sat IGS 1B (03-009B), the NOSS 3-2 duo (03-054A & 03-054C) and a piece of a Russian rocket stage (86-052D) that I caught as a bright stray.

This is the first time that I managed to get a good image of a NOSS pair. I snatched them close to the zenith, while traversing close to Vega. They show up surprisingly well in the image:

(click image to enlarge)



NOSS (Naval Ocean Surveillance System) satellites operate in pairs or triples (the older ones), orbiting close together, and locate shipping by tracking radio communications. They belong to the US Navy. Usually they are faint (mag. +5 to +6) but on occasion can appear brighter.



USA 186 Keyhole manoeuvred: connected to Georgia events or not?

USA 186 (05-042A) appeared somewhat late, but as the elset I had available was 10 days old I did not think anything particular about that. It was Pierre, who observed the same pass from France, who realized the sat had made a manoeuvre. This was confirmed by additional observations the next two nights by Pierre, Ted and Alberto.

Below is the image taken by me, showing USA 186 crossing close to M13 in Hercules:

(click image to enlarge)



The manoeuvre entailed adjusting the eccentricity and mean motion, and perhaps a small inclination adjustment. Perigee was brought down slightly, and apogee up, to a 261 x 1024 km orbit (was 264 x 1017 km).

Using a pre-manoeuvre elset by Mike and an adjusted version of Ted's post-manoeuvre elset, I find that the manoeuvre likely happend at Aug 14.6 UTC, some six hours before Pierre and my observation.

Satellites usually manoeuvre when the perigee is at the equator, as this minimizes fuell needed and maximizes results that can be obtained. USA 186 did not have it's perigee on the equator on the moment of manoeuvre however.

The manoeuvre comes at a time when chaotic war activities between Russia and Georgia are a focus of interest. This opens the question whether this manoeuvre of USA 186 (a Keyhole/improved Crystal satellite with high definition optical imagery capacities) is related.

Checking the pre-manoeuvre orbit against the post-manoeuvre orbit concerning passes over the relevant area of interest, it appears that the object was to synchronize passes as much as possible into a sequence where a daylight pass is followed exactly 11 hours later by a nighttime pass: with in addition an as exact as possible repeat of the observing geometry after 4 days. Whether or not this is related to the Georgia events, is a matter of speculation. Ted thinks it is not the case.

The patterning is apparent from this table (times are in UTC) showing passes over/near Georgia:

date____old orb___new orb
(2008)___pass______pass
-------------------------
15-8____06:58_____06:58

15-8____17:57_____17:58


16-8____07:22_____07:22

16-8____18:21_____18:22


17-8____06:08_____06:09

17-8____17:06_____17:09


18-8____06:32_____06:34

18-8____17:30_____17:34


19-8____06:55_____06:59

19-8____17:54_____17:58


20-8____07:19_____07:23

20-8____18:17_____18:22

------------------------


Daylight pass followed 11 hours later by nighttime pass (click images to enlarge)


Wednesday, 13 August 2008

IGS 1B flare, no Perseids

Yesterday was a strange evening. The day had been very clear, but with very strong wind (with gusts up to 100 km/h). In twilight, some clouds came in. It then got completely clouded, cleared again, and finally got clouded again, including a thunderstorm.

This all made me miss the Perseid meteor maximum. During the clearings however, I did manage to catch Lacrosse 2 (91-107A, in twilight), and the failed Japanese satellite IGS 1B (03-009B).

The latter was very bright (about +0.5) in the southeast and east. It then faded notably to +3, +3.5 just past east, and finally flared brightly to -1.5 in the northeast around 21:03:55 UTC.

I got three images of both satellites, totalling 11 positions (I dropped the faint trail end of the third IGS 1B image). The three IGS 1B images showed a second, very faint trail as well, which turned out to be the classified research MSX satellite (96-024A).

(click images to enlarge)


Tuesday, 12 August 2008

Oberg on the USA 193 shootdown

The renowned veteran space journalist and former mission control engineer James Oberg has published another article about the reasons for the USA 193 shootdown in february (see my detailed coverage of the USA 193 saga here).

Like in an earlier article, Oberg is strongly opposing suggestions that there is more to this all than the official reason given for the shootdown - the danger of the tank with Hydrazine reaching earth intact. He argues that that reason given was the true and sole reason.

As much as I respect Oberg, I am still not convinced (but then, I am merely only what Oberg calls an "amateur specialist". I observe satellites and determine their orbits. I do not launch them).

First, about disintegration of the satellite. Oberg makes an argument from a comparison with meteorite falls. That argument, at least in the way he presents it, is flawed.

Oberg argues - and he is correct in this!- that it is a widespread misunderstanding that meteorites arrive on earth surface 'red hot'. He points out that in fact they are cool when reaching earth surface, and then tries to argue that they do not heat up during their fall:

Though a thin outer layer is briefly exposed to very hot air, for most of the descent that air is thinner than the purest vacuum inside thermal-shielding thermos bottles.

Now he is correct in this: small meteorites indeed arrive cold on earth surface, and of the object which does reach earth surface, only a thin outer layer has been heated.

But this is only part of the story, and as such the meteorite analogy is a very poor one.

There are two reasons why meteorites arrive cold on Earth. One is that from 25 km altitude, after being slowed down by the atmosphere to subsonic speeds, they stop ablating and enter a free fall that takes minutes to complete. During this phase they cool, much like the air the ventilator in your pc blows over your computer CPU cools your CPU.

A more important factor however is that heat generated during the incandescent phase of a meteorite fall, the result of atmospheric friction when the object still has cosmic speeds, is carried away immediately with the ablating material. It is for this reason that heat generated does not transfer much into the meteorite. This is basically what Oberg points out, but he neglects to tell something which is quite relevant:

that in this process of meteorite ablation, at least 70% (and usually more) of the meteorite ablates and hence vanishes. What reaches earth surface is at best 20-30% of the original mass.


The implications for the USA 193 tank, if we properly use the meteorite analogy, is therefore this. Either one of these two things will happen:

1) over 70% of the tank mass ablates and at best 20-30% and probably less of the original tank mass will reach earth surface;

Oberg however argues specifically against the notion of the tank being destroyed by ablation. The alternative option which remains then is:

2) the tank, due to it's special construction, does not ablate. In that case however, the heat dissipation mechanism Oberg brings up in his meteorite fall comparison will be absent too. In other words: the tank will heat up in its interior, unlike a meteorite.

In this case, Oberg's analogy is flawed.

Now, if I understand Oberg's article correctly, modelling (and who am I to question this) of the USA 193 tank entry would have nevertheless suggested the frozen hydrazine to remain intact.

In that case, you can actually question what the real danger is of a solid chunk of hydrazine ice contained in a metal casing reaching earth surface. It will only be dangerous when someone directly handles it (but even then).

Here, we should realize that tanks with -unfrozen!- hydrazine fly through our airspace daily. Most fighter jets contain a tank with hydrazine as an emergency fuel backup. The effects of this falling down on you will not much differ from those of the USA 193 tank falling down on you. Such crashes are not rare. For example, our relatively modest Dutch airforce lost 32 of its F16 fighters, which carry a hydrazine tank, through flight crashes. Some of these aircraft came down in populated areas (one actually hit a house).

All commercial aircraft carry tanks with fuel too - not hydrazine, but still not pleasant stuff. Chances that one of these tanks will descend on your head - and this happens from time to time- are much larger than that the tank of USA 193 would have. And we don't quite bother about that. So why bother about the USA 193 tank then?

USA 193 was not the first failed fuel-carrying satellite to fall back to earth in an uncontrolled way. Nor will it be the last. In fact, launch failures where final rocket stages fail to fire are common. It will be interesting to see whether future cases will get a similar treatment.

In my opinion, the USA 193 shootdown was done for multiple reasons, and the "danger" of the hydrazine tank is only one of these. It is a convenient one to defend the exercise to outsiders, but not the only reason.

I am quite convinced that other reasons were of equal or even paramount importance in making the decision:
- that USA 193 presented a very convenient target for a practical test of ASAT capabilities (thus also making the money spent on the satellite at least partly pay off);
- that it would prevent new experimental technology falling (literally) into wrong hands;
- and that it was a timely moment to remind China, the US Senate and Congress and the US public that the USA has ASAT capabilities too and that the technology in a wider sense (missile defense) was worth further funding. Note that in April 2008, barely two montsh after the USA 193 intercept, the US Congress re-examined the status of missile defense of which the used Aegis system is part.


Note: considering the USA 193 shootdown, John Locker's summary and the links he provide are worthwhile reading

Saturday, 2 August 2008

Milky Way photograph, and a tale of lens covers...

Yesterday was one of those occasions... The evening was beautifully clear here. The passes of KH's USA 129 and 186 were too much in twilight (I did see USA 186 visually though, but got no points) and I tried to photograph a pass of IGS 1B half an hour later, using my new Tamron Di II AF 17-50/2.8 lens.

The Tamron lens needs to be focussed using the "live view" function of my camera (Canon EOS 450D), as it has no "hard stop" at infinity, like most modern lenses.

I ran into trouble though. Pointed it to Arcturus but no star to be seen on the screen whatever I tried. Dito with Vega, Deneb. Frustration! Then worry. Was my camera malfunctioning?!?

I looked up. And saw a bright IGS 1B majestically sail accross the sky. Grrr!

I took the camera again. And then the quarter finally fel....

Yep: forgotten to take off the lens cover....

* bangs head against desk repeatedly *

Later that evening I made a series of images with the 450D camera + Tamron lens piggyback on my ETX-70 telescope. 69 frames of 10 second exposure each at 800 ISO and 17mm/F2.8 were stacked into this image of the Milky Way in Cygnus, mimicking a 11.5 minute exposure:

(click image to enlarge)


Difficult to believe for me too that this was obtained right from a town center, but nevertheless it is true! Stacking large numbers of short exposure images makes this possible.

Friday, 1 August 2008

Results on the partial solar eclipse (UPDATED TWICE)

I could follow the entire partial solar eclipse this morning: the sky was clear, but with periodic fields of cumuli passing.

I made a series of photographs of the event through my Meade ETX-70. Below a first result, taken around local maximum of the eclipse (11:25 CEST, 09:25 UTC). Exposure 1/100s.


(click image to enlarge)


Here is a full series covering the eclipse, taken at approximately 10 minute intervals (except near first and last contact):

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And here is a time-lapse movie made from the images:

video

Wednesday, 30 July 2008

USA 186 and ISS

After a strange day with clouds in the morning, thunderstorm and pouring rain in the afternoon, and sun but cirrus in the late afternoon and early evening, it cleared during evening twilight.

I observed the Keyhole satellite USA 186 (05-042A) make a nice pass. Being invisible to the naked eye first, it made a short bright flare in Bootes and then brightened to mag. +3, being steady after that, crossing into Ursa Major. I got two trail photographs with the EF 50/2.5 Macro, on the last it disappears behind the roof. Hence, 3 points were the result. Compared to the 2.5 days old elset 08209.08611721 I have it 1.25 seconds late and 0.12 degrees off cross-track.

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A few minutes later the International Space Station made a fine pass. It was bright, at least -4 when traversing into Aquila. I shot a series of 10s pictures with the Tamron 18-50/2.5 lens at 18mm, and combined them into two stacks.

(click images to enlarge)


Monday, 28 July 2008

A 3D view of Cospar 4353

It is a bit frustrating: it is warm and sunny weather here but: the nighttime sky suffers from cirrus or thunderstorms. Hence, little observing opportunity.

Below image is a 3D red-cyan anaglyph image of the Cospar 4353 Leiden observing location which I shot last weekend. It was made from two photographs, with the camera slightly shifted, morphed into this anaglyph using Stereophoto Maker software.

To see the 3D effect, you need a pair of red-cyan 3D glasses (the red in front of the left eye, the cyan in front of the right eye). Click the image to get the large version.

(click image to enlarge)

Saturday, 26 July 2008

Nice evening twilight pass of the ISS

The International Space Station (ISS) made a nice zenith pass in a dark blue evening twilight sky this evening. I came back home from a diner with friends just in time to capture it.

The image below is a stack (digital sum) of two separate images of 10 second exposure each, taken with a 5 second interval between them. It was the inauguration of a new lens that was added to my equipment today: a Tamron Di II SP AF 17-50mm F/2.8 XR LD Aspherical (IF). The image was taken at 17mm. Camera: Canon EOS 450D at 800 ISO. There was some cirrus in the sky. The bright star just right of the trail is Vega.

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Monday, 21 July 2008

Early Ammonia Servicer (EAS)

This evening the sky was very dynamic: very clear, but also with lots of small rapid moving cloud fields traversing the sky.

I observed the Early Ammonia Servicer (EAS), 98-067BA, making a near zenith pass. Untill a year ago, EAS was part of the International Space Station ISS. On July 23rd 2007, during an EVA (Space Walk) by the ISS astronauts, it was detached from the station and ejected in space. Since then, the object, about the size of a large US refridgerator, has steadily spiralled down and currently is down to a 273 x 283 km orbit (ISS is at a 338 x 351 km orbit). If the current rate of decay continues, it will burn up in the atmosphere late 2008 or early 2009.

I observed it a year ago shortly after its release from ISS, and it was faint then, about magnitude +4 to +4.5. I observed it again this evening, and due to its much lower orbital altitude compared to last year it now reached mag. +2.5, perhaps even +2.0, in Cygnus while just past the zenith descending to the east. It moved fast.

I also managed to capture it on photograph, using the Canon EOS 450D and the EF 50/2.5 Macro lens stopped to +2.8. The image is below.

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Sunday, 6 July 2008

Lacrosse 2 and a splendid -7.5 Iridium 5 flare

After an overcast day with rain, holes started to appear in the cloud cover in the evening. They allowed me to capture Lacrosse 2 (91-017A) in a blue twilight sky, followed by a splendid magnitude -7.5 flare of Iridium 5 close to Arcturus seen through thin hazy clouds.

Lacrosse 2 flared as well to mag. -1 at 21:34:42 UTC (Jul 5).

The top image below shows Lacrosse 2 in twilight. The second picture shows the Iridium flare, with Arcturus at left.

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Saturday, 5 July 2008

Lacrosse 2 manoeuvred, and first results with the EF 50/2.5 Macro lens

Last two weeks I took several images in order to calibrate the timing of the new Canon EOS 450D camera. I finished the calibration just in time to catch positions of the SAR satellite Lacrosse 2 (91-017A), which manoeuvred twice last week. As usual, this happened with perigee on the equator.

The new Canon EF 50/2.5 Macro lens arrived as well. As promised by my friends who recommended it, it is a superb lens not only for macro photography, but also for astrophotography.

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Above are two examples of images I shot with the lens: one macro image of a seven-spotted ladybird (Coccinella septempunctata) on lavender in the Cospar 4353 garden; and an astrophotography result, obtained from Cospar 4353. The latter shows the area around Deneb in Cygnus, including the North America nebula. It is the result of a 'stack' (digital sum) of 98 individual exposures of 10s each (mimmicing a 16m20s exposure).

Combined with an ISO 800 setting on the camera, the EF 50/2.5 Macro goes much deeper than my previous Ixus camera's did, catching fainter objects. Last Tuesday and Wednesday nights, this was immediately apparent from the number of strays catched during satellite photography and a short astrophotography session.

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The lens (with 50 mm and a factor 1.6 equivalent to an 80 mm lens on an analogue camera) has about 25 degrees FOV, which is a 50% smaller FOV than I previously used, so pointing the camera correctly needs more attention. But the results are superb. On the stars, I get astrometric standard deviations of only 5" (5 arc seconds) typically. The satellite positions have a larger uncertainty, as they are also influenced by the timing accuracy.

The amount of noise produced by the EOS 450D sensor is much less than that by the Ixus camera's, and that pays off. While (unlike the Ixus) the camera does not standardly employ a noise reduction routine (which with the Ixus I suspected to sometimes "eat" part of the trails), the satellite trails stand out much better in the background, with less ambiguity as to where the trail ends.

Below are two images of last night: a single shot of Lacrosse 2 (91-017A), and a stack of two images taken shortly after each other. Relative to the pre-manoeuvre orbital elset (epoch 08177.99486268) the sat was 35 seconds early last night, on June 30 it was 2 seconds.

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Friday, 20 June 2008

Iridium flare, and a new camera

Last 1.5 month has seen very little activity here. Reasons behind that were a period with a stationary occlusal front bringing lots of clouds (and rain); a period where I was physically not entirely well; and the very late time at which at this time of the year it gets dark at my latitude (after local midnight only), which combined with my work schedule doesn't allow much observing mid-week.

Yesterday I did stay up until after midnight though. Because a new "toy" has arrived at Cospar 4353: a Canon EOS 450D DSLR camera, result of the investment of a tax return.

Below is an image I shot of a mag. -0.5 flare of Iridium 8 I shot last night. I used the EF-S 18-55 IS kit lens for it, at 18 mm F3.5 and ISO 800 with 15 seconds exposure.

Another lens, an EF 2.5/50 Macro which according to my friends yields superb results with astrophotography, arrives somewhere this weekend.

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