Saturday, 29 July 2006

Two classified SAR birds in one image

(click for larger image)

Under far from optimal conditions I was able to capture the trails of two
classified Radar birds on one image, only a few degrees apart: IGS 1B (2003-009B, #27699) and Lacrosse 4 (2000-047A, #26473).

This is a crop of the original image, reduced in resolution. In the center of
the image is Corona Borealis.

As the sky was very hazy the original colour image was quite fogged, so I
transferred it to B/W and then played with the contrast a bit to make the trails
stand out better.

It became overcast shortly after so no chance to capture the odd bird Lacrosse 5
again. My photograph of the 26th sparked a whole series of communications about the cause of the "disappearance trick" and the configuration of the Lacrosses in general.

Thursday, 27 July 2006

Lacrosse' 5 odd behaviour

Last night Lacrosse 5 (2005-016A, #28646) performed its amazing "disappearance trick" again, just as it did in March. This time however, it did while the camera was open: it was caught in the act of disappearing:

(click image for enlargement)

Movement is from bottom to top here. Lyra is well recognizable. You can see the trail quickly fading out (it takes maybe 2-3 seconds in total). In fact, the trail should end between 13 & 16 Lyr (the two stars above the trail) on this 10.7 s exposure. Also note that the satellite was nowhere near shadow entry at this time.

As Ted Molczan and Allan Thomson have stated, the suggestion is that a dark "something", perhaps an antenae panel, blocks view of the main body. At any rate, this behaviour is peculiar to Lacrosse 5 and not shown by Lacrosse 2, 3 & 4. In fact, Lacrosse 5 deviates in a number of things:

* it is brighter (visually and photographically);
* instead of red-orange it is yellow in colour;
* the other Lacrosse-birds don't do the "disappearance-trick"
(instead, they show short flares)

To which Ted Molczan added:
* It is also the first not to employ a frozen orbit.

Other observations I did the past days, observations which due to various reasons I did not come to discuss here yet were:

- Lacrosse 4 on July 23rd
- IGS 1B and Lacrosse 3 & 4 on July 21st
- Lacrosse 3 on July 18th

Monday, 17 July 2006

Clear skies continue

Clear skies continue, so last night I have been tracking again. For the first time in several weeks a Keyhole let itself be imaged again: USA 161 (2001-044A)was imaged as a very faint trail. No flares this time. Lacrosse 3 (1997-064A) made a nice bright crisp trail, and I captured IGS 1B (2003-009B) while it was cleearing the roof.

Staying up late (untill after 2 am) is taking its toll now though, so the next days I might opt for sleep instead.

Sunday, 16 July 2006

Lacrosse 3 and 90-046B as a stray

Catched Kosmos 2082rk (90-046B) as a bright stray together with Lacrosse 3 (97-064A).

NLC's and satellites

Last Friday evening saw a major display of Noctilucent Clouds here. Casper ter Kuiile sent out the first alert around 23:00 CEST through our DMS Alert Network. I made a short stroll throught the city untill I found a spot with visibility low enough down to the horizon. Nice, I hadn't seen the eery blue glow of NLC's for a few years.

Later that night I captured Lacrosse 3 and Lacrosse 5 Rk.

Friday, 14 July 2006

A nice and predicted Lacrosse 3 flare

Philip Masding predicted a flare of Lacrosse 3 (25017, 97-064A) for my site for this night (jul13-14), 00:22:22 UTC.

I watched Lacrosse slowly flare to mag. 0 at 00:22:27 +/- 1s UTC. So his prediction was correct by an error of only 5 seconds!

Below is the image I shot of the flare (click image for larger size). Earlierr this night I saw USA 161 briefly flare too.

Thursday, 13 July 2006

Tracking again, and imaging nightfall in time-lapse

After a period with clouded evening skies and/or no opportunity to track, last week saw some opportunities again. Yesterday and the day before I obtained images on Lacrosse 3, as well as IGS 1B, the latter having manouvred acoording to Pierre. I hope the good weather prevails, because Philip Mading mailed me a whole list with Lacrosse 3 flare predictions which I want to put to the test.

Yesterday night while tired and typing in the designations, I made a typo in the Cospar code for Lacrosse 3, which was diligently spotted by Russell.

Meanwhile I am still hooked by the time-lapse photography bug. Below is a movie showing nightfall over Cospar 4353, shot yesterday evening. Compressed into an 48 second movie is 4 hours of real time, starting 2.5 hours before sunset and ending 1.5 after sunset. The movie was made from 711 individual photographs.

Sunday, 9 July 2006

Another Time-Lapse movie

Another time-lapse movie which I made this afternoon. It is 1.5 hours (264 photographs) of moving cloud-scape shot between 13:10 and 14:40 CEST, compressed into a 18 second movie. Good Bye Blue Sky...see the dark clouds move in again... First experiment with adding some music too.

And obviously, with this type a dynamic atmosphere, there is little satellite tracking to be done..

Saturday, 8 July 2006

Time-lapse of frontal cloud cover arriving

I am experimenting a bit with time-lapse photography. Thanks to the digital revolution, this is quite do-able nowadays with the help of a digital camera, a lap-top (or pc), and some freeware and shareware available on the web.

Below 18 second .avi movie was made with my Canon Digital Ixus 400 hooked up to my lap-top, which thus controlled its operation. 181 pictures were taken over a timespan of 1.5 hours (so: one each 0.5 minute).

The attempt initially was to capture the clour-play of sunset on the high altitude cirrus clouds. But right after I started the series, a frontal low cloud cover came in.

Wednesday, 5 July 2006

Impressive clouds...

A thunderstorm developed here this morning. A few hours later, the clouds below appeared over the town, signifying the very unstable air. This picture was shot by me today (5 July 2006) at 13:00 CEST (11:00 UTC) from the Beestenmarkt, Leiden. I have tried to identify the type, and the best I can come up with is Stratocumulus opacus mamma.