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:

click image to enlarge

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.

click diagrams to enlarge

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.

Short observing session

Saturday evening saw a short break in the bad weather, and some clear sky. A slight haze and near full moon made the conditions not too excellent, but I managed to catch positions on Lacrosse 5 (05-016A) and the NOSS 3-2 duo (03-054A & C).

Below is a picture of the latter crossing near Polaris.

(click image to enlarge)

IGS 1B and NOSS 3-2 amidst flying clouds

Yesterday evening the atmosphere was very dynamic, with flying clouds. I did manage to capture the NOSS 3-2 pair (03-054A & C) in twilight, and IGS 1B (03-009B). The NOSS image suffered from twilight and clouds, but also yielded a fast stray (which I still have to identify).

IGS 1B was very bright again (+0.5) when it came out of eclipse and passed almost overhead. The picture below gives a good indication of the observing conditions.

(click image to enlarge)

Keyhole USA 186 manoeuvred at Aug 14.6, and imaging a NOSS duo (REVISED)

A late report on my August 14 observations and associated topics.

August 14 featured a nice clear evening. I captured the Keyhole USA 186 (05-042A), the Japanese failed radar sat IGS 1B (03-009B), the NOSS 3-2 duo (03-054A & 03-054C) and a piece of a Russian rocket stage (86-052D) that I caught as a bright stray.

This is the first time that I managed to get a good image of a NOSS pair. I snatched them close to the zenith, while traversing close to Vega. They show up surprisingly well in the image:

(click image to enlarge)

NOSS (Naval Ocean Surveillance System) satellites operate in pairs or triples (the older ones), orbiting close together, and locate shipping by tracking radio communications. They belong to the US Navy. Usually they are faint (mag. +5 to +6) but on occasion can appear brighter.

USA 186 Keyhole manoeuvred: connected to Georgia events or not?

USA 186 (05-042A) appeared somewhat late, but as the elset I had available was 10 days old I did not think anything particular about that. It was Pierre, who observed the same pass from France, who realized the sat had made a manoeuvre. This was confirmed by additional observations the next two nights by Pierre, Ted and Alberto.

Below is the image taken by me, showing USA 186 crossing close to M13 in Hercules:

(click image to enlarge)

The manoeuvre entailed adjusting the eccentricity and mean motion, and perhaps a small inclination adjustment. Perigee was brought down slightly, and apogee up, to a 261 x 1024 km orbit (was 264 x 1017 km).

Using a pre-manoeuvre elset by Mike and an adjusted version of Ted's post-manoeuvre elset, I find that the manoeuvre likely happend at Aug 14.6 UTC, some six hours before Pierre and my observation.

Satellites usually manoeuvre when the perigee is at the equator, as this minimizes fuell needed and maximizes results that can be obtained. USA 186 did not have it's perigee on the equator on the moment of manoeuvre however.

The manoeuvre comes at a time when chaotic war activities between Russia and Georgia are a focus of interest. This opens the question whether this manoeuvre of USA 186 (a Keyhole/improved Crystal satellite with high definition optical imagery capacities) is related.

Checking the pre-manoeuvre orbit against the post-manoeuvre orbit concerning passes over the relevant area of interest, it appears that the object was to synchronize passes as much as possible into a sequence where a daylight pass is followed exactly 11 hours later by a nighttime pass: with in addition an as exact as possible repeat of the observing geometry after 4 days. Whether or not this is related to the Georgia events, is a matter of speculation. Ted thinks it is not the case.

The patterning is apparent from this table (times are in UTC) showing passes over/near Georgia:

date____old orb___new orb
(2008)___pass______pass
-------------------------
15-8____06:58_____06:58
15-8____17:57_____17:58

16-8____07:22_____07:22
16-8____18:21_____18:22

17-8____06:08_____06:09
17-8____17:06_____17:09

18-8____06:32_____06:34
18-8____17:30_____17:34

19-8____06:55_____06:59
19-8____17:54_____17:58

20-8____07:19_____07:23
20-8____18:17_____18:22
------------------------

Daylight pass followed 11 hours later by nighttime pass (click images to enlarge)

Twice the ISS, and a bag of other objects

Yesterday I observed the International Space Station (ISS) twice. The first observation was in deep twilight, 20 minutes after sunset with the sun at only 4 degrees below the horizon.

I filmed this pass, using the "movie"-mode of my Canon Digital Ixus photo camera. The resulting short movie is below: it shows the ISS descending towards the east.



Later that evening, one pass later, I shot this photograph, which shows the ISS crossing Taurus just before entering earth shadow:

(click image to enlarge)

Both this evening and the morning of today (the 11th) I telescopically observed a number of other objects; the keyhole USA 129 (96-072A), the ELINT USA 32 (88-078A), the SAR satellites Lacrosse 5 (05-016A) and Lacrosse 3 (97-064A), and the NOSS 3-2 duo (03-054A & C) and, as a stray while waiting for USA 32, the old NOSS 6F (84-012F).

In addition, I shot this photograph of the crescent moon through my Meade ETX-70 in the late afternoon/early evening:

(click image to enlarge)

Observing ISS and two of its Progress cargo spacecraft

Yesterday evening was very clear, and provided the rather unique opportunity to see the International Space Station (ISS) pass in twilight, followed several minutes later by two of its cargo Spacecraft: Progress-M62 (07-064A) decoupled from ISS on Wednesday and now moving away from it carrying garbage, and Progress-M63 (08-004A) launched from Baikonur in Kazachstan on Wednesday and on its way to the ISS with fresh cargo. Seeing two Progress spacecraft in free flight on the same evening is unique.

ISS was the first to pass, still in deep twilight, at 18:15 local time, being around mag. -3. Five minutes later Progress-M62 followed on a trajectory a few degrees higher, grazing the Hyades cluster, and being about mag. +1. And twelve minutes after that, the newly launched Progress-M63 followed in a very similar trajectory. By that time, although the sky was still bright due to twilight, it was dark enough to try to photograph it. The resulting photograph has a very bright background drowning the trail, but after some image manipulation for brightness and contrast it is visible:

(click image to enlarge)

I logged a point for Progress-M63 through the telescope, and the endpoint of the trail on the image above provided a second point.

Later in the evening I observed Lacrosse 2 (91-017A), which by now was 34.6 seconds early, the USA 32 ELINT sat (88-078A), Lacrosse 5 (05-016A) and the NOSS 3-2 duo (03-054A & C), the latter duo on two consecutive passes.

Like previous days it was again clouded in the morning, so no chance to observe USA 193.

Tomorrow evening is going to prove very interesting, I hope. The weather prospects are good, and if the launch isn't postponed this evening, I will have a very good 80 degree post-twilight pass of Space Shuttle Atlantis STS-122. In addition, the ISS and the two Progresses can be observed again. Plus, the Soyuz rocket booster (08-004B) from the Progress-M63 launch could prove very interesting, as it will make two passes (one visible and one in shadow) while close to decay.

Lacrosse 2 manoeuvred again (updated)

Yesterday evening was very clear. While looking up some deep-sky objects and while waiting for target satellites to appear, I saw several faint strays.

Lacrosse 2 (91-017A) was 21.6s early and 0.16 degree off-track relative to a week old elset 08027.82795435. Hence, just like early January, it appears to have manoeuvred again.

Update: Russell Eberst's data of the same pass confirm my observation. From a very preliminary analysis I did, it seems that the manoeuvre entails a similar mean motion change by about +0.0005 as was the case early last month.

Other objects observed this evening were the ELINT sat USA 32 (88-078A) and the NOSS 3-2 duo (03-054A & C). In addition, I observed the International Space Station making a pass through Taurus just beneath the Hyades and Pleiades. I had not realised the decoupled Progress M-62 would be following it closely, so I missed that one (it also was just too far behind ISS to show up on the photograph I shot, see below).

(click image to enlarge)

It was overcast this morning so again no chance to observe USA 193. It is still overcast, so I am going to miss both the old and new Progress (the latter launched today) tonight. I hope it clears in time to observe them and the Space Shuttle STS-122 that is scheduled to launch next Thursday.

Peeping through holes in the cloud cover

The past two days the atmosphere has been very dynamic here. We had a gale yesterday, and both yesterday night and the night previous to that cloud cover and short but bright clearings followed each other up unpredictably.

I did try to do some observing, but as a result of these dynamic weather conditions I lost most selected objects to untimely cloud fields: apart from the NOSS 3-2 duo (03-054 A & C) on Wednesday night the 30th Jan.

When observing through the telescope, these NOSS duo's are very attractive targets. They operate in thight couples (the older ones even in trio's), crossing the same field of view with usually only a few seconds between them. It is very cool to see two bright yellow sparks chase each other through the FOV.

NOSS-es are operated by the US Navy, the acronym meaning Naval Ocean Surveillance System. They intercept radio traffic from ships and use it to pinpoint the locations of enemy shipping.

My trusted Oregon Scientific DCF-77 clock (a radio controlled clock getting its time signal from an atomic clock in Frankfurt) died last Wednesday after years of faithful service. Wednesday evening I temporarily used the clock on my weather station, which is also DCF-77 controlled, as a back-up, but I do not completely trust it so I ordered a new DCF-77 as a replacement for the failed one. It arrived today.