An update on IGS-1B

Along the line of expectations, our tracking data show that the Japanese spy satellite IGS 1B (2003-009B) which malfunctioned in March 2007, keeps coming down (see earlier coverage here and here).

Early July 2011, the perigee had come down to 450 km and the Mean Motion (the number of orbital revolutions per day) is steadfastily increasing as the orbit becames more narrow:





The predicted decay date keeps shifting back and forth, being highly dependant on solar activity. Solar activity has been back to modest the past two months. As a result, the decay date forecast has shifted further away in time.

If solar activity does not increase, forecasted decay will be in late 2013 (SatEvo with current solar flux F10.7 cm = 85, elset 11184.15154535). If it does increase - which is likely, as we are on the approach to a solar maximum - it will be earlier, possibly as early as mid-2012.



Meanwhile, it is interesting to see how the still active sister-ship IGS 1A (2003-009A), launched in the same 2003 launch, is faring. Above diagram shows the evolution of the orbital inclination. IGS 1B's orbital inclination is clearly drifting, consistent with loss of control. IGS 1A's orbital inclination initially was allowed to co-drift with IGS 1B, but then altered in a manoeuvre mid-2008 that brought the inclination up again, to match the other IGS-es in the constellation. As of 2010, it is kept more or less steady, librating around a value of 97.39 degrees, the sun-synchronous value for a 487 x 498 km orbit.

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.

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)