Saturday 29 April 2006

Lacrosse 3 & Lacrosse 5 rocket, plus IGS 1B

After 20 days of forced non-activity, I managed to obtain some data again last night. Weather conditions were instable. It had been clouded much of the day, but cleared around dusk. Yet large fields of cumulus would come and go. I missed passes of Keyholes USA 129 and 186 due to this, and one of two passes of Lacrosse 3.

I did catch Lacrosse 3 during another pass, although Murphy almost struck again. The battery of the camera turned out to be near-empty, so it quit after the first image.

Later that night I also managed to get two pictures on IGS 1B (during the same pass) and a picture of the Lacrosse 5 rocket. In all, a nice set of data

IGS 1B crossing the Big Dipper amidst flying clouds

Monday 10 April 2006

Visit Bram Dorreman

Today noted satellite observer Bram Dorreman, chair of the BWGS, payed me a visit. It was good to meet one of the frequent names from SeeSat list in real. For several hours, we talked about observing activities, astronomy and a few personal things. Bram showed a bit of the kind of observational data he collects, and I demonstrated the basics of my photographic technique of positional measurements.

Sunday 9 April 2006

Keyhole Flare Galore!

(click photo for full size image)

Yesterday evening was a fine clear evening again, with several interesting passes. I got treated with a nice set of Keyhole flares.

Most spectacular was USA 186 (2005-042A, #28888). I saw it and photographed it while it was producing two short brilliant flares of mag. -1.5 within 10 seconds while passing just below the tail of the Big Dipper. See the photograph above (30:17:46.8 should read 20:17:46.8, sorry for that typoe).

Next was another Keyhole, USA 129 (1996-072A, #24680), which produced a slow long flare up to mag. +0.5 in the N-NW at 21:11:10 +/- 5s UTC.

I got two good positions on USA 186, and one on USA129. In addition, I got two positions on the Japanese IGS 1B. With the latter I was lucky, as an untimely very local patch of clouds almost threatened to obscure it (see photograph below). It was very bright again at mag +1.5, while coming out of eclipse.

The points on both USA 186 and USA 129 agree very well in delta T and cross-track with the latest elsets for these satellites; however the points on IGS 1B are clearly off (0.1 degree) in cross-track compared to elset 06096.85488870 and I believe this is a true deviation, not a measurement error. These points are also some 2 seconds early.

Thursday 6 April 2006


A late report on yesterday evening, due to circumstances.

Good clear sky again. First tried to cover the passes of USA 186 and USA 129. Both were too faint this time however. USA 129 nevertheless made one short bright flash (mag. 0) at 21:17:32 UTC.

Over the past two days, other observers (e.g. Pierre, Bruce) too commented on the irregular brightness behaviour of 2005-042A (USA 186), just as I did in my previous post and report on my April 4th observation.

Yesterday I did catch IGS 1B (2003-009B), the Japanese radar Intelligence Gathering Satellite. It starts to slowly get higher in the sky during passes, and hence slowly into view. I viewed and photographed it as it emerged out of eclipse just above the roof of the opposite building. It was very bright, mag.+1.5 and brightening. On the photograph, the trail ends behind the roof, so hence I could only measure the startpoint. the trail is clear and crisp on the image, and the resulting point is almost exactly 1s early with regard to elset 06093.83849704.

Wednesday 5 April 2006

Two Keyholes

Yesterday evening I spotted two Keyholes, an old one and a new one: USA 129 (96-072A, #24680) and USA 186 (05-042A, #28888).

USA 186 was the first, and I saw it emerging from eclipse at 40 degrees altitude under the tail of the Big Dipper at 20:13 UTC. It was very irregular in brightness and made at least two flashes, the brightest of which was about mag. +1 at 20:13:05 +/- 3 sec UTC. I caught only a very faint marginal trail on the photograph,marginall also afteer some digital image enhancement. The endpoint was undeterminable, the startpoint I hope is indeed the startpoint...

Half an hour later USA 129 made a zenith pass around 20:47 UTC. It was too faint to be either seen or photographed in the actual zenith (20:46:40 UTC) but clearly showed up a minute later, well past the zenith. Good trail on the image, no problems measuring it.

Sunday 2 April 2006

Nice bright USA 129 pass captured

Beautiful clear sky this first April evening. USA 129 made a nice bright zenith pass, easily visible by the naked eye at mag. +2.5. I obtained 3 images, hence 6 points. The trail on the 3rd image is faint, so the last two points should be used with care.

4 out of 6 points are about 3.4 to 3.5 seconds late with respect to Mike's elset 06088.79862438, and clearly off cross-track again by some 0.10 to 0.15 degrees. Lutz Schindler reports similar results from the same pass.