Chasing satellites through clouds and unusual brightness behaviour of the STSS Demo 2

The evening of Saturday-Sunday 20-21 February saw a very dynamic weather situation. Fields of clouds came and went very rapidly: the sky could go from clear to clouded to clear to clouded again in a matter of minutes. It made it a big gamble whether a particular object would eb visible or not.

As it came to be, I hauled a nice batch of positions on several objects: Lacrosse 5 (05-016A), the Lacrosse 5 r/b (05-016B), the STSS Demo 2 (09-052B) and the NOSS 3-2 (03-054A & C) duo. I also photographed the NOSS 3-4 duo but the image was too much hampered by cliuds tp reliably measure it. I lost amongst others Lacrosse 4 and the STSS Demo 1 to clouds (the latter a pitty, as it was predicted to pass right through the Pleiades).

Most of the images have some clouds on them: some extensively. Below are a few pictures: from top to bottom they show the Lacrosse 5 r/b amidst clouds; The NOSS 3-2 duo passing between the Pleiades and the Hyades; and the STSS Demo 2 passing near capella and the three Goats:

click images to enlarge

The STSS Demo 2 appears to show an unusual brightness variation in the first 2 seconds of the trail (the left part of the trail in below negative image), consisting of what appear to be a series of even spaced modest glints. Note the dashed appearance of the first part of the trail:

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Below is the brightness profile over the trail (grey small crossmarks are individual pixel values, the solid line is a 3 point average), and below that is a graph of the time between brightness maxima visible in the profile.

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Note in the second diagram how the time between maxima is very constant, at about 0.13 seconds, during roughly the first 2 seconds . After that, it begins to wildly vary. As the first diagram shows, the amplitude of the brightness variations is larger in those first 2 seconds too. In fact, after those first two seconds the variation is largely or completely random pixel variation.

The first 2 seconds of the trail are quite different in character from the rest of the trail though: a clear constant, larger amplitude pulsing behaviour. This is very interesting. A second image obtained on the STSS Demo 2 during the same pass showed a quite constant brightness.

Lacrosse 5 passing alpha Persei

Earlier this week, on February the 24th, the generally very bad weather of this moment gave way to a short period of clear skies after dusk. This allowed me to obtain some positions on the bright SAR satellite Lacrosse 5 (05-016A) and it's spent rocket booster Lacrosse 5r (05-016B).

Below is an image showing Lacrosse 5 passing close to alpha Persei and the alpha Persei star association.

(click image to enlarge)

A very clear night, Lacrosses, the Breeze-M tank and the Pleiades

Yesterday evening (22 Dec) was very clear. I obtained photographs of the passes of the Lacrosse 5 rocket (05-016B), and Lacrosse 4 (00-047A)..

I photographed Lacrosse 4 with the Pleiades just before eclipse (see below). When inspecting the image for astrometric reduction, I noted a second, fainter trail on the image. Measuring it and running an ID, I found it was close to predicted positions for the Breeze-M (deb) tank, 05-019C. There was an odd 0.6 degree discrepancy though. Mike solved it by pointing out that a SDP4 solution yielded perfect residues, while the SGP4 theory SatFit uses doesn't. So, the question mark plus the "UNID" in below image can be erased.

(click image to enlarge)

Later that night, after the LEO window closed, I spent some time doing astrophotography with my camera piggyback on my Meade ETX-70. I still have to stack part of the images, but already finished stacking 102 x 10s exposures of the Pleiades with the EF 50/2.5 lens, yielding this result:

(click image to enlarge)

Defeated by the weather?

Just as the, perhaps last, visibility window of the by now world-famous USA 193 (06-057A) is starting here, weather has turned bad. Yesterday evening I could still observe the Keyhole USA 129 (96-072A) and the spent rocket boosters Lacrosse 5r (05-016B) and NOSS 3-4r (07-027B) under already hazy conditions: but now, heavy fog is hiding the skies and all what moves along it.

The USA 193 craziness is still continuing. Following the news that it will be shot with a missile somewhere next week - perhaps Wednesday/Thursday night, see also my ongoing updates here - this weblog is attracting an enormous amount of traffic again. Even more than the previous time USA 193 was in the news, late January.



Yesterday I was called by a journalist from the NRC, one of the "quality" newspapers of my country. This resulted in a short piece on USA 193, with some mention of our amateur observing work and me, in today's scientific pages.

This evening the NOS (our Dutch "BBC") called for a short informative chat, as they might do an item on it the coming days.

With all this, I should almost forget to report that I have been observing a lot the past days, taking advantage of three consecutive days of nice clear skies. Targets on these nights were the satellites and rocket bodies mentioned above, especially USA 129.

I also experimented further with photographing the moon through my ETX-70, in preparation for the lunar eclipse of coming Wednesday-Thursday night (that I am affraid I am going to lose to fog and/or clouds). With the help of a few euro of hardware I bought at a hardware store on Saturday, I made an extension to my telescope to firmly attach the camera to the eyepiece.

Below is one of the results. It is a mosaic composite of three images taken in the evening of February 17th. It is 2600 x 2600 pixels wide, 880 kB (click it to see it in full detail).

(click image to enlarge)

Here's a part-image of the southern highgland with a.o. the craters Tycho, Clavius and Schiller:

(click image to enlarge)