Wednesday 29 November 2006

UARS impostering as ISS, the real ISS, Lacrosses and a rocket stage

This morning was very fine. I obtained 15 positions on 5 objects: Lacrosse 2 (91-017A), Lacrosse 3 (97-064A), UARS (91-063B), an old Russian Soyuz rocket stage (70-037B), and the International Space Station, which made a fine pass again.

And I almost got fooled by a celestial imposter!

At the end of the fine pre-dawn session I was waiting for a pass of the ISS. While preparing the camera I realised I had used elements from before the scheduled orbit boost for ISS, so I reckoned it might perhaps appear somewhat off-time (later, it turned out I made a mistake in this anyway, as the boost would only occur his evening and not last evening as I thought by mistake...).

At 5:42 UTC, 1 minute early, I saw a bright object appear in Gemini close to but slightly south of the point where ISS should emerge from earth shadow. It initially was about mag. +0.5 in brightness. "Ah, there it is!" I thought and triggered the camera...

(click image to enlarge)

As the camera ended its exposure, I realized something was wrong...

My brain registered disappointment about the brightness of this "ISS", then wondered about a 1 minute early appearance (a bit too much??), and as I watched the object I realized its course was bringing it much too much north to be, this was an imposter!

So I quickly swapped back the camera. And yes, there it appeared,low west, almost at te moment I turned my sight to it: the real ISS, close to Castor and Pollux, at a splendid bright mag. -3...!

(click image to enlarge)

The "imposter" was later identified as te Upper atmospheric research satellite UARS (91-063B, #21701). The darn thing almost fooled me...! :-P

Like from my images of last Friday, I constructed a mozaic of two ISS trail images from this morning again:

(click image to enlarge)

It is well visible how bright ISS is just after coming out of earth shadow.

Apart from ISS and UARS, I also imaged Lacrosses 2 & 3 this morning, and recorded a second stray on one of the Lacrosse 2 images, which turned out to be 70-037B (#04394), an old Russian Soyuz rocket stage from the Meteor 1-4 launch, 1970.

Tuesday 28 November 2006

Satellites, ISS and an Asteroid

This morning was another clear and still morning. A bit of haze and a small patch of thin clouds every now and then. Like the previous morning, I observed Lacrosse 2 & 3 (91-017A & 97-064A) and a zenith pass of the International Space Station. I obtained 2 images and thus 4 points on each object.

97-064A and 91-017A (Lacrosses 3 & 2) appeared some 10 minutes after each other in the same sky area with almost the same sky elevations, range and illumination phase. This made me appreciate the somewhat different intrinsic brightness between the two (Lacrosse 3 seems a bit fainter), which was clear visually and to some extend also on the photographs.

(click image to enlarge)

ISS was nice and bright at about mag. -2 when emerging out of shadow crossing the legs of Ursa Major near the zenith (see image below), yet not as bright as last Friday.

Meanwhile, todays' DOU in MPEC 2006-W103 contained the publication of my latest asteroid discovery, 2002 BF32 (packed: K02B32F). It is a 1 km large (H17.6) MB II main belt asteroid which I discovered in NEAT archive images from January 2002 last week. It has perihelion at 2.1 A, aphelion at 3.1 AU and an orbital inclination of 12 degrees. The orbital arc is short, I managed to track it over only 3 nights.

(click image to enlarge)

Monday 27 November 2006

Lacrosses and ISS

Another clear morning, albeit slightly hazy. Targets were Lacrosse 2 (91-017A, #21147), Lacrosse 3 (97-064A, #25017) and the International Space Station.

The ISS was less bright than last Friday, at about mag. -1.5 shortly after exiting shadow in Canes Venatici. It was "white" this time. The positional residues are nice:


Lacrosse 2 (91-017A) was bright (mag. +2) as it came out of shadow and traversed the tail of Ursa Major. I obtaned 1 picture, 2 points. It was 0.4s late and 0.2 degrees off-track relative to an 8-day old elset.

Lacrosse 3 (97-064A) was fainter (mag. +3.0 to +3.5). I obtained 2 images, hence 4 points. was 1 second late but on-track relative to an 8-day-old elset.

(Click images to enlarge)

Friday 24 November 2006

A Lacrosse, a Lacrosse rocket and the ISS (updated)

(Click images to enlarge)

I was up early this morning. The sky had cleared, although streaks of fast-moving clouds still wandered across the sky.

First target was Lacrosse 3 (97-064A,# 25017) around 5:17 local time (4:17 UTC). It was faint, the trail on the photograph was rather marginal. My results suggest it was 0.15 seconds late and 0.1 degree off-track relative to a 5-day old elset, but as the trail was very marginal, don't pin me down on it.

Next target was the Lacrosse 5 Rk rocket stage (05-016B, #28647). While traversing from Auriga into Gemini around 5:57 local time it was quite bright, magnitude +1. Once in Leo at 5:58 local time, it had faded to mag +3.5. Got 2 photographs and hence 4 positions, but the last one dropped because it came out clearly erratic. The other three points more or less agree, and suggest it was on-time and on-track.

Highlight of the night was a fine pass of the International Space Station at 6:37 local time (5:37 UTC), see the two pictures above. When it came into view at about 35 degrees altitude, close to Procyon, it already was well into the negative magnitudes, about magnitude -3 I estimate. It stayed that bright while crossing the body of Leo and passing close to Saturn at about 55 degrees altitude: it dimmed when going towards the eastern horizon. It had a somewhat orange colour again.

I have seen ISS this bright before, but that was during zenith passes. I wonder what brightness it currently could attain in the zenith. Hope to be able to check that out soon, as ISS starts to make more favourable morning passes.

UPDATE: I've combined the two ISS pass photographs into one composite image
(click image to enlarge)

Monday 20 November 2006

Lacrosse 4 results (update)

My observations of yesterday (last two lines, in bold, station 4353) compared to elset 06323.75609492 and a few other station's data for Nov. 16-19, 2006. X-track and positional error in degrees, delta T in seconds. As I said: nice residuals.

Lacrosse 4
1 26473U 00047A 06323.75609492 0.00000140 00000-0 26459-4 0 07
2 26473 67.9958 184.9503 0005500 264.0178 95.9822 14.64305775 03

STA YYday HH:MM:SS.sss____XTRK deltaT Perr

2420 06320 16:51:34.620__-0.01__0.07 0.020
2675 06320 18:30:25.860__-0.02_-0.20 0.040
2675 06320 18:32:29.700__-0.04_-0.27 0.122
2675 06320 18:33:01.760__-0.02_-0.03 0.023
2751 06322 18:04:36.150___0.01_-0.05 0.024
2751 06322 18:04:42.260__-0.01_-0.05 0.019
2751 06322 18:05:56.050__-0.04_-0.14 0.076
2675 06322 19:44:55.430___0.05_-0.01 0.049
2675 06322 19:45:37.100___0.06_-0.03 0.062
4353 06323 18:41:51.100___0.05__0.01 0.045
4353 06323 18:42:01.800___0.08__0.05 0.081

rms 0.05949

Sunday 19 November 2006

Lacrosse 4 lucky shot

Date 06323.78 - The past days has seen the same frustrating pattern: either a fully clouded day, or a day with clear skies in daytime and midnight, but clouds in the evening and morning.

This evening however, I made a very lucky shot of Lacrosse 4 (00-047A, #26473) as it traversed Lyra at 40 degrees altitude in the west. There was a gap in the clouds, I stood on the courtyard, waiting with my DCF clock in hand and camera ready, watching the clouds move in again, muttering to myself and the Lacrosse: "Come on, COME ON...!". Then Lacrosse 4 cleared the roof, I triggered the camera, followed by 10 tense seconds before it opened, another 10 seconds of exposure with the sat running for the clouds, and then a "whew!" from me as the exposure finished just seconds before Lacrosse 4 disappeared in the clouds. A very close call!

Below image shows I am not kidding. This has been a very lucky shot. Obtained 2 points with good residues (the bright star on the image is Vega).

(click image to enlarge)

Monday 13 November 2006

Update on previous post

An update on my previous post: Lacrosse 5 appeared nicely on-time with nice residuals for 3 out of 4 points compared to Mike's elset 06315.73014711:

06317__17:56:11.800___0.07___1.59*__0.742*__dropped point

(Values with Scott Campbell's Satfit, X-track and Pos. error in degrees and delta T in seconds)

I dropped the last point because of its obvious anomalous character. This point is not the real end of the trail at the end of the exposure: but the point where the quickly fading satellite dropped in brightness below the imaging sensitivity treshold of the camera, some 1.5 seconds before the end of the exposure.

This underlines the quick fading at that moment: from +1.5 to below the imaging treshold in a mere 10.2 seconds.

Lacrosse 5 flaring & irregular

Date 06317.75 - After a long period with heavy rain and clouds, the sky cleared this afternoon. Although sky conditions were not perfect (it remained somewhat hazy, hence a bright sky background in the urban environment of SatTrackCam Leiden), it allowed me to observe and image the 17:55 UTC pass of Lacrosse 5 (05-016A, # 28646).

(click images to enlarge)

The satellite showed a rather irregular brightness behaviour. While I was setting up my camera it made a short bright flare to mag. 0 low in the west at about 17:53:50 UTC (+/- 10s) lasting only a few seconds. After that it went back to much less brightness (mag +2 to +2.5).

While climbing towards Vulpecula it brightened slowly to mag. +1.5 at 17:55:00 - 17:55:10 UTC. The first of the above pictures captures it during this bright phase.

Next I had to operate the camera, but when looking up at around 17:55:30 it was fainter, about +2.5. Between 17:55:50 and 17:56:10 UTC it brightened again to +1.5 in Vulpecula during a few seconds, then quickly dimmed again and actually went out of visual detection range for me just after 17:56:10 UTC. I captured the peak brightness and fading part on photograph, the rapid fading near the end is apparent in it. See the second picture above (satellite movement is from right to left).

Note that the satellite was nowhere near shadow entry at this moment: in fact, it should have been approaching its maximum brightness at this moment instead of fading.

Update: the endpoint on the second image turns out to be the point where the satellite brightness drops below the imaging sensitivity treshold of the camera, some 1.5 seconds before the end of the exposure: see update post here.

Thursday 2 November 2006

Lacrosse 5 doing its tricks amidst hailshowers

Like the previous evening I was able to observe Lacrosse 5 (05-016A, #28646), during a clearing in between heavy hail showers (you can see one approaching on below image).

At mag. +2.5 to +2.0, Lacrosse 5 was clearly less bright than the previous evening, even though it moved in about the same sky trajectory (but an hour earlier in time).

While crossing under Polaris, it did its infamous "disappearance trick" again, becoming notably fainter in a mere few seconds. This time, although it was beyond reach of the camera sensitivity (the camera has an about mag. +3.5 limit for satellites), I could still see it with the naked eye as a faint mag. +4 object. The drop in magnitude happened while I was making my second exposure, and it is clearly visible how it fades rapidly in the image below. The sudden brightness change happened at about 17:39:26 UTC.

(click image to enlarge)

I managed to obtain two trail pictures (including the one above), plus a third which did not show the satellite as it had become too faint. In all, this yielded 4 points. The satellite was almost a second late now.

A second pass of Lacrosse 5 at 19:19 UTC was missed due to cloud cover.

During twilight I observed a nice impressive pass of the International Space Station (ISS). I watched it as it moved between patches of clouds against a still blue twilight sky, attaining a brightness of about mag. -2 and a maximum elevation of about 62 degrees. It had an orange-reddish colour, something reported by various observers since the recent addition of additional solar panels to the Space Station.

Wednesday 1 November 2006

SatTrackCam Report no. 1

As I wrote yesterday, today SatTrackcam Leiden completed its 15th month of operational activity. Which means it is time for an evaluation. In the form of a 20-page report:

SatTrackCam Report no. 1: The First 15 Months (Aug 2005 - Oct 2006).

It can be downloaded as a 320 Kb pdf file here.

Unfortunately, for this public version I had to remove a chapter and appendix with a detailed analysis of the accuracy of the results, as it made use of data which I am not allowed to redistribute. The public version of the report does describe the equipment, software and methods used, and summarizes the results.

Lacrosse 5

Today the weather consisted of rainshowers with intermittent (very) clear spells.

During such a clear spell this evening, I observed a nice pass of Lacrosse 5 (05-016A, #28646) near 18:33 UTC and obtained two photographs yielding 4 good quality positions. A third photograph lost the satellite in a local swift moving patch of clouds.

Lacrosse 5 was steady and bright again, attaining mag. +1.5 at maximum brightness. It was 0.6s late relative to elset 06301.76685028

MT Milcom monitoring, plus report forthcoming

Larry van Horn of the MT Milcom Monitoring Blog spent a short post about my recent orbit plots on this blog today, as I discovered from a spike in my Blog traffic statistics. His Blog is about monitoring radio communications from military satellites and satellite relays.

Listening to military and other satellite signals (e.g. ISS to ground communications on 143.625 and 145.800 MHz) is something I have done in the past too, until my old receiver went West.

On another note: tomorrow (or now, as it is past midnight here) SatTrackCam Leiden has been operational for 15 months. Time for an evaluation! I worked on a 15 page report about these past 15 months the past days, which I hope to finish and post a link to tomorrow.

Weather is very bad here at the moment. Heavy rainshowers, and an alert for heavy storm in the north of the country.