Brightness variation of the USA 198 Centaur rocket stage on October 30, 2014

Earlier today I posted this image of the USA 198 Centaur rocket (2007-060B) passing close to M33 galaxy in Triangulum:

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I noted a slight but clear brightness variation in the trail segments on subsequent images (the stack above is a stack of 19 individual images). I therefore decided to use the images to create a brightness variation profile.

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The result is the diagram above (grey crosses are individual pixel values; the blue line is an 11-point sliding average; the red dotted line a sinusoid with a period of 37 seconds). This is the result of combining measurements of the trail brightness variation on 20 images. The individual pixel values are noisy, the result of using a high ISO setting of 2000 (which results in noise) but a pattern is visible, even more so in the 11-point sliding average.

The diagram shows a modest but clear semi-regular brightness variation with a peak in brightness approximately each 37 seconds. There is perhaps also a regularity visible in that each second valley in the curve is more shallow than the first. The pattern suggests a slow tumbling motion.

Below is one of the original individual images:

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USA 198 r/b passing the M33 galaxy

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Last Thursday evening was very clear. I tested a clip-in CLS filter on my Canon EOS 60D, employing the 2.8/180mm Zeiss lens and a motorized tracking mount.

One of the targets was M33, a big galaxy in Triangulum. As it happened (it was not planned), I captured a classified object in the series: the USA 198 r/b (2007-060B). It can be seen passing M33 in the image above, which is a stack of several 20-second images (breaks in the trail represent short moments inbetween consecutive exposures).

As the images do not have the timing accuracy of my usual tracking images, they are probably of little use for astrometry. But I do seem to see some slight brightness variation, so I might try to construct a brightness curve.

A keyhole flare, and an SDS-3 satellite (USA 198)

Last two evenings were clear. On September 7th I watched and imaged the KH-12 Keyhole USA 129 (96-072A), together with my neighbour who saw her first Keyhole this way.

On September 8th I imaged both USA 129 and another KH-12 keyhole, USA 186 (05-042A). USA 129 briefly flared to mag. +0.5 at 20:49:21.7 UTC. Below is the image, and the brightness profile (the image saturates near the flare peak). In the same image, slightly below and to the right, another faint trail can be seen: this is a rocket stage, 08-049B, from the launch of a Thai communication satellite in 2008, launched from Russia with a Dnepr rocket, a converted ICBM.

click images to enlarge

I also imaged two high altitude objects: again the USA 144/Misty-2 decoy (99-028C, see my post here and here) and USA 198 (07-060A), an SDS-3 communications satellite in a Molniya orbit. One of the tasks of this type of satellite, is believed to be the relay of data from the Keyholes to ground stations.

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Below animated GIF shows USA 198 as a moving object (moving from left to right) just right of the frame center:

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)

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:

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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:

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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.