Saturday 30 September 2006

Lacrosse 3 & Lacrosse 5rk cruising up together

This evening I caught Lacrosse 3 (97-064A, #25017) and Lacrosse 5rk (05-016B, #28647), the rocket stage of the Lacrosse 5 launch, cruising up together in the sky in close proximity and same direction.

(Click image for larger picture)

I managed to get only this one picture, as the battery of my camera was empty and hence my camera shut off after this image. Lacrosse 3 was about mag.+2, Lacrosse 5rk about +2.5.

There was some cirrus in the sky. Contrast has somewhat been enhanced in the posted image crop, to enhance the trails. Stars visible are mainly from Ursa minor and Draco, Polaris is in the upper right corner of the image.

97-064A was only 0.1s late relative to 6-day-old elements (elset 06267.82859916). 05-016B was 2.2s late relative to a week old elements (elset 06266.84118421).

Monday 25 September 2006

Illustrative diagrams

These two diagrams I prepared this weekend from recent observational data by stations Cospar 710, 2420 and me (4353) on KH-12 USA 186 (05-042A, #28888). They are compared to Mike's orbit elset 6261.8706146.

It very graphically demostrates the need for continuous orbital updates using our tracking data. As can be seen, data start to deviate quickly, due to orbital perturbations of the satellite, past the epoch date. Within 5 days after the elset epoch the satellite passes already 3 second early, a good degree off in position. This is why there is a continuous need for new tracking data.

Sunday 24 September 2006

Lacrosse 2

A second front passed yesterday, bringing a few raindrops in the morning. Around dusk it cleared for a while, but the sky remained very hazy. Nevertheless managed to image Lacrosse 2 (91-017A, # 21147). It was only 0.1s early and on-track, no surprises. A quickly deteriorating sky prevented other tracking attempts.

Friday 22 September 2006

USA 186 Flare Galore

Yesterday evening at the 20:44 UTC pass I was treated to two nice flares by KH-12 Keyhole USA 186 (2005-042A, #28888). Both flares happened while the camera was open (on two consecutive images). The second flare at 20:44:43 +/- 2s UTC amidst the stars of Ursa minor was brilliant, reached magnitude -2 and took over 10 seconds. The result was the fine photograph below:

(click image for larger version)

The earlier flare ( a glint rather) was near the zenith and a short one, reaching magnitude +1 at 20:43:46 +/-2s UTC with a duration of less than a second.

(click image for larger version)

The positions obtained from the photographs suggest USA 186 (05-042A) appeared 1.8 sec early and 0.06 deg off-track relative to elset 06261.87061463.

I almost lost these two observations! I was busy with answering fireball reports pouring in on a bright almost-daylight fireball that appeared at 17:35 UTC and in doing so lost track on the time. So at 20:42 UTC I suddenly realised a USA 186 pass was imminent at 20:44 UTC! I jammed open the window, slammed the camera tripod on the courtyard, slammed the camera n it and got two very lucky shots...!

I have two older observation runs to report as well.

On Sept 20 I catched a faint trail of USA 186, as well as a bright trail of Lacrossse 2 (1991-017A, #21147).

On Sept 18th I observed two other short glints of USA 186, one of which was photographed:

* 21:10:12 ± 2s UTC very short, mag. -1. Caught on photo, flare appears near-stellar

* 21:10:35 ± 2s UTC again very short, mag. +0.5

On the photograph with the 21:10:12 UTC flare, the trail is very faint pre- and post-flare. I obtained one position (endpoint of the trail seemed defined enough to measure).

Monday 11 September 2006

Flare update and Cospar 4353 on Google Earth

Pierre observed in the same flarepath of USA 186 (05-042A) yesterday evening as the one that caused the flare I observed. From western France, he saw it flare about 40 seconds earlier than I did from the western Netherlands.

On an unrelated note: below is a Google Earth image where I have circled the location of SatTrackCam Leiden. The courtyard is well visible.

USA 186 flare, and is it manoeuvring?

KH-12 type Keyhole optical imaging reconnaisance sat USA 186 (05-042A, #28888) brightly flared to mag. -2 in the northwest at 21:13:06 ± 3s UTC. When I first saw it, looking up from triggering the 10 second camera selftimer, it was very bright, and it faded gradually as the camera opened (see image below). It was a very slow flare lasting tens of seconds, unlike the very brief glints I had observed so far from this satellite (e.g. report and photograph here).

(click image for larger picture)

It was as much as 9 seconds early and 0.10 deg off in cross-track with respect to 4 day old elset 06249.87384698, and 2.5s early with respect to Russel's observations 25 hours earlier: is it manoeuvring?

About an hour earlier I also captured another keyhole, USA 129 (96-072A, #24680). The trail was faint, the two obtained positions are about 1s early.