Below image started some 10 seconds after the flare peak and shows USA 129 still bright, fading from +1 to +2, between Leo's bum and the coma cluster.
(click image to enlarge)
Wednesday, 11 April 2007
USA 129: 0.6s early and bright
USA 129 (96-072A) flared again to mag. -1 at about 19:56:50 UTC in the bum of Leo. It was some 0.6s early, so it looks like no manoeuvre yet. On the 9th perigee of the satellite coincided with equator crossing, which is usually the moment KH's manoeuvre.
Below image started some 10 seconds after the flare peak and shows USA 129 still bright, fading from +1 to +2, between Leo's bum and the coma cluster.
Below image started some 10 seconds after the flare peak and shows USA 129 still bright, fading from +1 to +2, between Leo's bum and the coma cluster.
Monday, 9 April 2007
Chasing Keyholes
The past two evenings where very clear again. I spent them chasing Keyholes and Lacrosses.
USA 129 (96-072A) and USA 186 (05-042A) provided some nice flares again. On Saturday the 7th, USA 129 displayed a slow -1 flare at 20:01:00 UTC, and a +2 flare very low in the west during the second pass at 21:38:40. The next evening, its cousin USA 186 flared to mag. 0 at 20:22:30 UTC in pretty much the same local sky area as USA 129 did the previous evening. In both cases they peaked in brightness before my first exposure started, and I catched them fading again (see image below).
I also obtained my first point on the Japanese radar sat IGS 1B (03-009B) since its reported failure. It came out of eclipse just above the rooftops, the trail on the image is still faint and hence I am not too confident in the single position I obtained.
In the next few weeks, moving away from spring equinox, the IGS-es will come higher and higher in the sky. There is a new set of recently launched IGS objects I hope to start tracking besides IGS 1B.
As usual the Lacrosses were covered again too. Lacrosse 5 (05-016A) did its "disappearance trick" again on the 7th at 19:30:17 UTC. The other Lacrosse target was Lacrosse 2 (91-017A).
For yesterday evening, I had USA 129 less than 0.1 s "late", but clearly off-track by 0.08 degree. USA 186 was as much as 0.9s late but on-track. Lacrosse 2 was less than 0.1s "early" and on-track.
The image below shows USA 129 (96-072A) some 15 seconds after a flare peak, still being mag. +2, crossing near the Coma cluster on the 7th.
USA 129 (96-072A) and USA 186 (05-042A) provided some nice flares again. On Saturday the 7th, USA 129 displayed a slow -1 flare at 20:01:00 UTC, and a +2 flare very low in the west during the second pass at 21:38:40. The next evening, its cousin USA 186 flared to mag. 0 at 20:22:30 UTC in pretty much the same local sky area as USA 129 did the previous evening. In both cases they peaked in brightness before my first exposure started, and I catched them fading again (see image below).
I also obtained my first point on the Japanese radar sat IGS 1B (03-009B) since its reported failure. It came out of eclipse just above the rooftops, the trail on the image is still faint and hence I am not too confident in the single position I obtained.
In the next few weeks, moving away from spring equinox, the IGS-es will come higher and higher in the sky. There is a new set of recently launched IGS objects I hope to start tracking besides IGS 1B.
As usual the Lacrosses were covered again too. Lacrosse 5 (05-016A) did its "disappearance trick" again on the 7th at 19:30:17 UTC. The other Lacrosse target was Lacrosse 2 (91-017A).
For yesterday evening, I had USA 129 less than 0.1 s "late", but clearly off-track by 0.08 degree. USA 186 was as much as 0.9s late but on-track. Lacrosse 2 was less than 0.1s "early" and on-track.
The image below shows USA 129 (96-072A) some 15 seconds after a flare peak, still being mag. +2, crossing near the Coma cluster on the 7th.
(click image to enlarge)
Friday, 6 April 2007
Flaring USA 193 and USA 186
The past 3 nights were very clear and transparent, and with the moon gone, this meant good opportunities for observations in the evening.
Yesterday evening I was treated to some nice flares, and observed USA 193 (06-057A) being very bright for the second time.
The bright appearance of USA 193 was again on a west-southwest pass, just like two days ago. In other parts of the local sky, it remains too faint to observe for me. But like my observation of two days ago, it now again reached magnitude +1.5, easily visible to the naked eye (and camera eye).
The bonus was in a sudden bright flare it produced at 19:37:50 UTC. It was a short but bright flare (about 1 second duration) reaching magnitude -1.5 and with a conspicuous yellow-orange colour. This alas happened some 10 seconds after the end of my exposure.
Now I do know it is so bright when appearing in this part of the sky, I'll start to monitor these south-western passes of USA 193 (earlier I had given up after trying to observe several passes in the northern sky in vain).
Keyhole USA 186 (05-016A) was another target of last evening, and it produced two flares, a slow one to mag. -2 at 20:53:40 UTC and a fast one to mag. 0 at 20:54:10 UTC. Again, not while the camera was opene: I did catch the last fading part of the first flare though, the sat still being mag. +2.5 when my camera opened some 5 seconds after the peak of the first flare.
I had USA 193 some 0.6 to 0.7 seconds late and on-track with regard to Ted's latest elset 07094.84492728, and USA 186 some 3.1 to 3.3 seconds early with regard to Mike's elset 07090.85107920 and notably off-track by 0.05 to 0.08 degree.
During the two nights previous to this I obtained a rich haul of positions on USA 129 (96-072A), USA 193 (06-057A), and Lacrosse 2 & 5 (91-017A & 05-016A). Especially the evening of the 3rd was a bounty, with 15 positions gathered.
Below images from last evening show USA 193 traversing Gemini at mag. +1.5, and USA 186 fading from it's first flare.
Yesterday evening I was treated to some nice flares, and observed USA 193 (06-057A) being very bright for the second time.
The bright appearance of USA 193 was again on a west-southwest pass, just like two days ago. In other parts of the local sky, it remains too faint to observe for me. But like my observation of two days ago, it now again reached magnitude +1.5, easily visible to the naked eye (and camera eye).
The bonus was in a sudden bright flare it produced at 19:37:50 UTC. It was a short but bright flare (about 1 second duration) reaching magnitude -1.5 and with a conspicuous yellow-orange colour. This alas happened some 10 seconds after the end of my exposure.
Now I do know it is so bright when appearing in this part of the sky, I'll start to monitor these south-western passes of USA 193 (earlier I had given up after trying to observe several passes in the northern sky in vain).
Keyhole USA 186 (05-016A) was another target of last evening, and it produced two flares, a slow one to mag. -2 at 20:53:40 UTC and a fast one to mag. 0 at 20:54:10 UTC. Again, not while the camera was opene: I did catch the last fading part of the first flare though, the sat still being mag. +2.5 when my camera opened some 5 seconds after the peak of the first flare.
I had USA 193 some 0.6 to 0.7 seconds late and on-track with regard to Ted's latest elset 07094.84492728, and USA 186 some 3.1 to 3.3 seconds early with regard to Mike's elset 07090.85107920 and notably off-track by 0.05 to 0.08 degree.
During the two nights previous to this I obtained a rich haul of positions on USA 129 (96-072A), USA 193 (06-057A), and Lacrosse 2 & 5 (91-017A & 05-016A). Especially the evening of the 3rd was a bounty, with 15 positions gathered.
Below images from last evening show USA 193 traversing Gemini at mag. +1.5, and USA 186 fading from it's first flare.
(click images to enlarge)
Tuesday, 3 April 2007
My first USA 193 (06-057A) observation
I just observed the (reportedly failed) spysat USA 193 (06-057A) for the first time. Usually it stays too faint for me, but this time it was very bright, about mag. +1, just before eclipse entry, crossing Gemini. It was moving fast, a very fine sight. Below is the image I obtained.
Full report on the other observations of this fine evening later.
Full report on the other observations of this fine evening later.
(click image to enlarge)
Monday, 2 April 2007
More KH flare fun
Observing a flare as a bonus to position determinations keeps being the icing on the cake for me. Last night Keyhole USA 186 (05-042A), the real one this time ;-) , did it again. I flared to magnitude -1 in the zenith at 21:01:10 UTC.
My camera opened about 10 seconds later, when the satellite was already well past the flare maximum. It is still of about mag. +2 at the start of the trail on the image, but fades to invisibility during the exposure.
Other targets imaged last night were the SAR satellites Lacrosse 5 (during two passes) and Lacrosse 2.
Lacrosse 2 (91-017A) was 2.3s early. Lacrosse 5 (05-016A) 0.4s late. USA 186 was on-time.
I am eagerly awaiting the opening of the springtime visibility window of the Japanese radar satellite IGS 1B (03-009B). After several years of operation this satellite recently reportedly failed in orbit. While operational its orbit was tightly controlled by almost daily small orbit manoeuvres keeping it very steady. It is interesting to see whether that level of control is now dropped (early results by other trackers indeed suggest such).
My camera opened about 10 seconds later, when the satellite was already well past the flare maximum. It is still of about mag. +2 at the start of the trail on the image, but fades to invisibility during the exposure.
Other targets imaged last night were the SAR satellites Lacrosse 5 (during two passes) and Lacrosse 2.
Lacrosse 2 (91-017A) was 2.3s early. Lacrosse 5 (05-016A) 0.4s late. USA 186 was on-time.
I am eagerly awaiting the opening of the springtime visibility window of the Japanese radar satellite IGS 1B (03-009B). After several years of operation this satellite recently reportedly failed in orbit. While operational its orbit was tightly controlled by almost daily small orbit manoeuvres keeping it very steady. It is interesting to see whether that level of control is now dropped (early results by other trackers indeed suggest such).
Wednesday, 28 March 2007
Another case of identity confusement
It must be in the air or something, but yesterday evening I again mixed up two satellites, and again it involved USA 186.
This time, I observed a magnitude zero flare in the zenith at 20:35:10 UTC and mistakenly reported it to the Seesat list as being a flare of USA 186 (05-042A).
In reality, it was another Keyhole, USA 129 (96-072A). USA 186 would pass 10 minutes later along a similar track...
It shows up on two images (both taken after the flare) and yielded 4 positions, the last of which is probably in error.
I also covered two passes of Lacrosse 5 (05-016A). The first pass was a twilight pass and Lacrosse 5 remained "hidden" most of that pass, except for a brief period of maybe 30 seconds after 19:14:10 UTC, when it suddenly appeared just east of Polaris at about mag. +2.5. Lutz reported it was gone again by 19:14:47 UTC.
The second pass saw no disappearance event. Lacrosse 5 was bright and steady, and four photographs yielded 8 positions.
With regard to the night previous to this, I can add a few things. First the confusion between Keyhole USA 186 and the weathersatellite NOAA 14 when the latter was producing a brilliant flare. As can be seen from the following diagram, the two were indeed cruising up very closely at that time, hence why they were so easily confused. At the time of the bright flare which I captured on photograph, they were only 8 degrees apart in azimuth and 0.2 degrees in elevation.
In addition, I can also report that I obtained positions on USA 129 and Lacrosse 5 that night.
This time, I observed a magnitude zero flare in the zenith at 20:35:10 UTC and mistakenly reported it to the Seesat list as being a flare of USA 186 (05-042A).
In reality, it was another Keyhole, USA 129 (96-072A). USA 186 would pass 10 minutes later along a similar track...
It shows up on two images (both taken after the flare) and yielded 4 positions, the last of which is probably in error.
I also covered two passes of Lacrosse 5 (05-016A). The first pass was a twilight pass and Lacrosse 5 remained "hidden" most of that pass, except for a brief period of maybe 30 seconds after 19:14:10 UTC, when it suddenly appeared just east of Polaris at about mag. +2.5. Lutz reported it was gone again by 19:14:47 UTC.
The second pass saw no disappearance event. Lacrosse 5 was bright and steady, and four photographs yielded 8 positions.
With regard to the night previous to this, I can add a few things. First the confusion between Keyhole USA 186 and the weathersatellite NOAA 14 when the latter was producing a brilliant flare. As can be seen from the following diagram, the two were indeed cruising up very closely at that time, hence why they were so easily confused. At the time of the bright flare which I captured on photograph, they were only 8 degrees apart in azimuth and 0.2 degrees in elevation.
(click diagram to enlarge)
In addition, I can also report that I obtained positions on USA 129 and Lacrosse 5 that night.
Monday, 26 March 2007
Of brilliant flares, and confusion... (UPDATED & CORRECTED)
UPDATED & CORRECTED
In the original version of this post, I wrote:
Hence it was not USA 186 flaring. In fact, an ID run with IDSat and a full satellite catalogue identified the flaring object as NOAA 14 (94-089A, #23455), a weather satellite.
They were cruising up together only a few degrees apart, hence the misidentification. USA 186 is known to produce flares, so when I saw a satellite flaring up near the USA 186 position I assumed it was USA 186....in error.
More results on this night will be posted later in a second post.
In the original version of this post, I wrote:
A quick post about the two nice flares by Keyhole USA 186 (05-042A)I just observed. The first occurred in the zenith at 20:23:25 UTC just after the end of my first exposure. It reached mag. 0. A second bright slow flare reaching magnitude -1 happened at 20:24:15 UTC and this time the camera was open. The very fine result can be seen below.Well, forget that. And shamefaced here. When measuring the images, the delta T came out several seconds errative, and the cross-track error in position some 3-4 degrees.....and I don't make such mistakes, so the only option was that it must be another object...
Hence it was not USA 186 flaring. In fact, an ID run with IDSat and a full satellite catalogue identified the flaring object as NOAA 14 (94-089A, #23455), a weather satellite.
They were cruising up together only a few degrees apart, hence the misidentification. USA 186 is known to produce flares, so when I saw a satellite flaring up near the USA 186 position I assumed it was USA 186....in error.
More results on this night will be posted later in a second post.
(click image to enlarge)
Friday, 23 March 2007
A Lacrosse 5 Disappearance and Re-appearance
Yesterday evening at about 20:20 UTC I saw Lacrosse 5 (05-016A) do its "disappearance trick" again: this time however followed by a re-appearance about half a minute later.
Disappearance - I observed it being very bright (mag. 0) while ascending in the sky. Just when I was aiming my camera and about to trigger it, it disappeared in a few seconds time. Completely out of naked-eye range. This was at about 20:19:30 UTC, but this time can be somewhat off for reasons stated below.
Re-appearance - At 20:19:50 ± 5 seconds UTC (I am more certain of this time) it re-appeared again in a few seconds time, close to Capella, attaining a brightness of magnitude +1. From that moment on it was steady, gradually fading to mag. +2, crossing the Big Dipper and Draco untill I lost it behind the building.
The photograph below was taken within half a minute of it re-appearing again and shows that it was very bright again.
The observation was a bit chaotic because my neighbour started a chat with me and I was explaining my observations to her when Lacrosse 5 disappeared (hence why the time of that event did not entirely stuck in my memory). Moreover her cat tried to hug my tripod, so I gently had to scoop the animal away.
I also catched USA 129 (96-072A) and USA 186 (05-042A) last evening, but the trails were very faint and I could not get unambiguous positions from them.
I also have a late report to make on the evening of March 14th, when I gathered a total of 6 positions on Lacrosses 2 & 3.
Disappearance - I observed it being very bright (mag. 0) while ascending in the sky. Just when I was aiming my camera and about to trigger it, it disappeared in a few seconds time. Completely out of naked-eye range. This was at about 20:19:30 UTC, but this time can be somewhat off for reasons stated below.
Re-appearance - At 20:19:50 ± 5 seconds UTC (I am more certain of this time) it re-appeared again in a few seconds time, close to Capella, attaining a brightness of magnitude +1. From that moment on it was steady, gradually fading to mag. +2, crossing the Big Dipper and Draco untill I lost it behind the building.
The photograph below was taken within half a minute of it re-appearing again and shows that it was very bright again.
The observation was a bit chaotic because my neighbour started a chat with me and I was explaining my observations to her when Lacrosse 5 disappeared (hence why the time of that event did not entirely stuck in my memory). Moreover her cat tried to hug my tripod, so I gently had to scoop the animal away.
I also catched USA 129 (96-072A) and USA 186 (05-042A) last evening, but the trails were very faint and I could not get unambiguous positions from them.
I also have a late report to make on the evening of March 14th, when I gathered a total of 6 positions on Lacrosses 2 & 3.
(click image to enlarge)
Monday, 12 March 2007
Lacrosse 2 running early
Lacrosse 2 (91-017A), the oldest in the Lacrosse (Onyx) SAR-satellite series still in orbit, is running increasingly early. Yesterday evening it already was over 7 seconds early and clearly off-track relative to a 4 day old elset. Is it going down for a de-orbit?
Yesterday evening saw very clear skies. I gathered a nice batch of data: two images (4 positions) on Lacrosse 2 (91-017A), two images (4 positions) on Lacrosse 3 (97-064A), and three images (6 positions) on USA 129 (96-072A). Plus in addition to this, I catched a stray in one of the Lacrosse 3 images, which turned out to be a 22-year-old Russian rocket booster, Kosmos 1689 Rk (85-090B, #16111).
Below is one of the three images I shot of USA 129.
This evening I skipped tracking activities. I am not feeling well and decided to take some rest instead.
Yesterday evening saw very clear skies. I gathered a nice batch of data: two images (4 positions) on Lacrosse 2 (91-017A), two images (4 positions) on Lacrosse 3 (97-064A), and three images (6 positions) on USA 129 (96-072A). Plus in addition to this, I catched a stray in one of the Lacrosse 3 images, which turned out to be a 22-year-old Russian rocket booster, Kosmos 1689 Rk (85-090B, #16111).
Below is one of the three images I shot of USA 129.
This evening I skipped tracking activities. I am not feeling well and decided to take some rest instead.
(click image to enlarge)
Saturday, 10 March 2007
Flaring Keyhole USA 129
There was cirrus in the sky in daytime, persisting after sunset. Only after 9 pm local time, the sky had cleared enough from haze to attempt photography. This left only one target, USA 129 (96-072A, #24680), a Keyhole imaging satellite.
It made a zenith-pass near 20:21 UTC during which it put on a spectacular show.
As it cleared the edge of the roof and came into my view in the zenith, it was very bright and clearly flaring. It must have been around mag. 0 to -1, peaking near or before 20:21:20 UTC. When my camera opened it was already past peak brightness for several seconds but still bright, gradualy fading. The image is below.
Obtained two positions from the image. My timings suggest it was 1.15s early with regard to elset 07066.85705303
It made a zenith-pass near 20:21 UTC during which it put on a spectacular show.
As it cleared the edge of the roof and came into my view in the zenith, it was very bright and clearly flaring. It must have been around mag. 0 to -1, peaking near or before 20:21:20 UTC. When my camera opened it was already past peak brightness for several seconds but still bright, gradualy fading. The image is below.
Obtained two positions from the image. My timings suggest it was 1.15s early with regard to elset 07066.85705303
(click image to enlarge)
A Keyhole and two Lacrosses
Another clear evening last night. I managed to catch one KH and two Lacrosses.
The KH was USA 129 (96-072A). It appears as two rather faint trails on two images: the starting point on the first trail is behind the building. I have it running 0.7s early relative to a 2-day-old elset. I obtained 3 positions
Lacrosse 2 (91-017A) was as much as 1.5s early and 0.1 degree off in cross-track relative to a similar aged elset. I obtained 3 positions.
Lacrosse 3 (97-064A) by contrast was pretty much on-time and on-track. It made a nice bright trail. It briefly and modestly flared up to maybe +1.5 at about 19:49:45 UTC, just before shadow entry. I obtained 2 positions.
The KH was USA 129 (96-072A). It appears as two rather faint trails on two images: the starting point on the first trail is behind the building. I have it running 0.7s early relative to a 2-day-old elset. I obtained 3 positions
Lacrosse 2 (91-017A) was as much as 1.5s early and 0.1 degree off in cross-track relative to a similar aged elset. I obtained 3 positions.
Lacrosse 3 (97-064A) by contrast was pretty much on-time and on-track. It made a nice bright trail. It briefly and modestly flared up to maybe +1.5 at about 19:49:45 UTC, just before shadow entry. I obtained 2 positions.
Thursday, 8 March 2007
Clear skies at last!
After a month of being clouded out, clear skies at last this evening! I targetted two Lacrosse satellites: Lacrosse 2 (91-017A) and Lacrosse 3 (97-064A). An attempt was also made to capture USA 129, but it was too faint for the camera.
Both Lacrosse satellites made a nice pass, reaching about mag. +2.5. Lacrosse 3 (97-064A) was on-time and on-track. Lacrosse 2 (91-17A) however, was some 0.2s late and 0.1 degree off-track. The photograph (see below) shows that it slowly brightened about midway in the exposure. I dare not call it a flare however, as it is rather marginal.
On below image of the Lacrosse 2 trail: Castor and Pollux at left, alpha Auriga at right. The sat moves from bottom to top.
Both Lacrosse satellites made a nice pass, reaching about mag. +2.5. Lacrosse 3 (97-064A) was on-time and on-track. Lacrosse 2 (91-17A) however, was some 0.2s late and 0.1 degree off-track. The photograph (see below) shows that it slowly brightened about midway in the exposure. I dare not call it a flare however, as it is rather marginal.
On below image of the Lacrosse 2 trail: Castor and Pollux at left, alpha Auriga at right. The sat moves from bottom to top.
(click image to enlarge)
Saturday, 3 March 2007
GRRRRR!!!!!
Yesterday we were having steel blue skies in the afternoon. So I reckoned that perhaps that evening I would get a chance to see sats again, as the past 3-4 weeks were grey and cloudy.
But nope. Heavy cirrus cover wandered in at dusk. I tried to shoot a Lacrosse 3 pass, saw it visually but the image is too fogged.
Meanwhile, the crocuses in the garden have withered. Their place have been taken by the small bright blue-purple flowers of the lesser Periwinkle. The image below was shot by me last Wednesday. Due to the strange weather, flowers etc. are about 1 month early in schedule this year.
But nope. Heavy cirrus cover wandered in at dusk. I tried to shoot a Lacrosse 3 pass, saw it visually but the image is too fogged.
Meanwhile, the crocuses in the garden have withered. Their place have been taken by the small bright blue-purple flowers of the lesser Periwinkle. The image below was shot by me last Wednesday. Due to the strange weather, flowers etc. are about 1 month early in schedule this year.
(click image to enlarge)
Wednesday, 28 February 2007
Clouded skies, first signs of Spring
The skies again have been (and are) clouded again for a long time here. So I have little in term of observations to report lately. I do hope the conditions improve soon.
This anyway is a strange winter so far. It is the warmest on record since the start of measurements in AD 1706. So far, I measured only two days with the minimum temperature below zero degrees C on the station.
As a result, shrubs and plants are flowering already. Especially the crocuses have been flowering in abundance the past two weeks. Below are two photographs I shot with the Canon Digital Ixus 400 (the same camera used for the satellite imagery). The top one is from last Friday (shot in a small forest nearby), the other one a week earlier. The latter are crocuses in the courtyard of SatTrackCam.
This anyway is a strange winter so far. It is the warmest on record since the start of measurements in AD 1706. So far, I measured only two days with the minimum temperature below zero degrees C on the station.
As a result, shrubs and plants are flowering already. Especially the crocuses have been flowering in abundance the past two weeks. Below are two photographs I shot with the Canon Digital Ixus 400 (the same camera used for the satellite imagery). The top one is from last Friday (shot in a small forest nearby), the other one a week earlier. The latter are crocuses in the courtyard of SatTrackCam.
(click images to enlarge)
Tuesday, 6 February 2007
Current situation
It is back to clouded here. I could not take advantage of the very clear days last weekend, as satellite passes high enough for my location and bright enough were all morning passes. Due to the return of severe insomnia problems, I am back on a 1 week cure of sleeping medication currently, which means it is not a good idea to set the alarm-clock for early in the morning as my docter wants me to sleep at that time.
I did take advantage in the daytime however, by going through the city with my camera. You can see some of these recent photographs of scenic Leiden (single shots as well as composed panorama's) here.
If you hover your mouse over a picture thumbnail before clicking it to view it, the tag on the location where it was taken will highlight on the Leiden map on the page.
I did take advantage in the daytime however, by going through the city with my camera. You can see some of these recent photographs of scenic Leiden (single shots as well as composed panorama's) here.
If you hover your mouse over a picture thumbnail before clicking it to view it, the tag on the location where it was taken will highlight on the Leiden map on the page.
Friday, 26 January 2007
More Lacrosse 5, and an old-timer (Kosmos 624) showing up
Having bouts of insomnia is not fun, as it is very tiring. yet the good thing about it, is that it promotes satellite observations.
I was awake very early in the morning yesterday (Jan 25th) after managing only a few hours of sleep. At 5:30 am local time I decided to make something good out of something bad, by checking whether there were any satellite passes to observe. It turned out Lacrosse 3 (97-064A, #25017) made a nice zenith pass, emerging out of eclipse just south of the Big Dipper. So I observed and imaged it.
It was a very dark and transparent, cold night (-0.7 C, the first night with true frost at Cospar 4353 this winter, ridiculously late). Lacrosse 3 was bright, magnitude +2, and I obtained 2 images (hence 4 positions).
As an unanticipated extra, there was a faint second trail on the first image. It was clearly shorter than the Lacrosse trail, so at first I was in some doubt whether it was a satellite at all and not for example a meteor.
I could subsequently positively ID it however as Kosmos 624 (73-104H, # 06992) an old 1973 Soviet Strela-1M communications satellite. Amazing as it "should" have been mag. +7 only (instead it was something like mag. +4, judging from the trail. I did not see it visually)!
The reason the trail was so short, is that its orbit is higher than that of my usual targets: it was at over 1500 km altitude at the time of observation. It must also be the smallest object I imaged so far, as its RCS is only 0.8 m^2.
In the evening I made a second observing run, imaging Lacrosse 5 (05-016A) and Lacrosse 4 (00-047A). Like the previous nights, Lacrosse 5 performed its "disappearance trick" again, this time at 17:23:23 UTC. Before that time is already was somewhat variable, alternating between mag. +1 and +2.5. The observation was done in a blue twilight sky. Upcoming cirrus and a nearby moon prevented me from observing a later second pass of the satellite.
I was awake very early in the morning yesterday (Jan 25th) after managing only a few hours of sleep. At 5:30 am local time I decided to make something good out of something bad, by checking whether there were any satellite passes to observe. It turned out Lacrosse 3 (97-064A, #25017) made a nice zenith pass, emerging out of eclipse just south of the Big Dipper. So I observed and imaged it.
It was a very dark and transparent, cold night (-0.7 C, the first night with true frost at Cospar 4353 this winter, ridiculously late). Lacrosse 3 was bright, magnitude +2, and I obtained 2 images (hence 4 positions).
As an unanticipated extra, there was a faint second trail on the first image. It was clearly shorter than the Lacrosse trail, so at first I was in some doubt whether it was a satellite at all and not for example a meteor.
I could subsequently positively ID it however as Kosmos 624 (73-104H, # 06992) an old 1973 Soviet Strela-1M communications satellite. Amazing as it "should" have been mag. +7 only (instead it was something like mag. +4, judging from the trail. I did not see it visually)!
The reason the trail was so short, is that its orbit is higher than that of my usual targets: it was at over 1500 km altitude at the time of observation. It must also be the smallest object I imaged so far, as its RCS is only 0.8 m^2.
In the evening I made a second observing run, imaging Lacrosse 5 (05-016A) and Lacrosse 4 (00-047A). Like the previous nights, Lacrosse 5 performed its "disappearance trick" again, this time at 17:23:23 UTC. Before that time is already was somewhat variable, alternating between mag. +1 and +2.5. The observation was done in a blue twilight sky. Upcoming cirrus and a nearby moon prevented me from observing a later second pass of the satellite.
(click images to enlarge)
Successful simultanious observations of Lacrosse 5 "disappearance"!
On January 22 and 24, Philip Masding in the UK and me in the Netherlands managed to observe and time two Lacrosse 5 (05-016A) "disappearances" simultaniously. Phil obtained some marvelous lightcurves showing the brightness behaviour of the satellite during these passes.
Interestingly, the clocked times of disappearance are similar for Phil's location in the UK near Manchester (53.4 N, 2.4 W) and for me in Leiden, the Netherlands (52.2 N, 4.5 E), 485 km to the East of Phil.
Interestingly, the clocked times of disappearance are similar for Phil's location in the UK near Manchester (53.4 N, 2.4 W) and for me in Leiden, the Netherlands (52.2 N, 4.5 E), 485 km to the East of Phil.
Table with 05-016A "disappearance events" on-line
For anyone interested in having a go at modelling the enigmatic "disappearance" events of Lacrosse 5 (05-016A): in addition to the list maintained by Philip Masding at his website, I have posted my own timings of such disappearance event over the past year at:
http://home.wanadoo.nl/marco.langbroek/L5d_4353.txt
The list on that URL ( a link to it is in the right-hand sidebar of this blog too) will be updated whenever I time a new event of this type.
http://home.wanadoo.nl/marco.langbroek/L5d_4353.txt
The list on that URL ( a link to it is in the right-hand sidebar of this blog too) will be updated whenever I time a new event of this type.
Wednesday, 24 January 2007
Another Iridium flare, Lacrosse 4 and another Lacrosse 5 "disappearance"
This evening another Iridium flare was predicted for my location. Iridium 76 (98-048B, #25432) was predicted to flare to mag. -4.8 at 18:16:41.7 UTC at virtually the same sky location as yesterdays Iridium 03 flare.
The flare was very fine again. A field of clouds passing by added a dramatic touch to the scene, as can be seen in the photograph below.
A quarter of an hour earlier, I observed and photographed a fine pass of Lacrosse 4 (00-047A, #26473). It passed close to the Pleiades cluster again, making for a scenic picture (see below). I obtained two images, hence 4 points. Lacrosse 4 was some 0.35s late.
A minute after the Iridium 76 flare, I switched my attention to Lacrosse 5 (05-016A, #28646). It was bright as it climbed from Cygnus through Andromeda to Cassiopeia. Just before my camera opened for the first exposure, it however did its "disappearance trick" again, this time at 18:18:18 UTC (ugh, if you are nutty enough to believe in numerology (which I don't) that is a Devilish time to do trics for a clandestine sat....6+6+6:6+6+6:6+6+6 !).
The flare was very fine again. A field of clouds passing by added a dramatic touch to the scene, as can be seen in the photograph below.
(click image to enlarge)
A quarter of an hour earlier, I observed and photographed a fine pass of Lacrosse 4 (00-047A, #26473). It passed close to the Pleiades cluster again, making for a scenic picture (see below). I obtained two images, hence 4 points. Lacrosse 4 was some 0.35s late.
(click image to enlarge)
A minute after the Iridium 76 flare, I switched my attention to Lacrosse 5 (05-016A, #28646). It was bright as it climbed from Cygnus through Andromeda to Cassiopeia. Just before my camera opened for the first exposure, it however did its "disappearance trick" again, this time at 18:18:18 UTC (ugh, if you are nutty enough to believe in numerology (which I don't) that is a Devilish time to do trics for a clandestine sat....6+6+6:6+6+6:6+6+6 !).
Odds of a mag. -7.5 Iridium flare, and twice Lacrosse 5 its tricks
Another clear (and cold) evening, although clouds began to appear at 19h UTC. Positions were obtained on Lacrosse 5 (05-016A, #28646) and Lacrosse 4 (00-047A, #26473), as well as Iridium 03 (98-048A, #25431).
Highlight of the evening was a splendid magnitude -7.5 flare by Iridium 03 at an altitude of 44 degrees and azimuth 28 degrees (north-northeast) at 18:22:50.8 UTC.
The image above was shot from the street in front of the almshouse complex (it was just too low in the sky to be visible from the courtyard of the complex) with a 10.7s exposure between 18:22:47.1-18:22:57.8 UTC. The flare had a predicted brightness of mag. -7.5, and indeed must have been in that order. The center of the flare path was 4.8 km West of me (while the Iridium satellite was over Denmark, at 785 km altitude and a range of 1069 km north-northwest of me).
Chance had it that the people from Grimbergen observatory in Belgium (Philippe Mollet et al.) located 135.9 km south of my location, observed the same flare from the same Iridium. While I had the center of the flarepath at 4.8 km West of me at 18:22:50.8 UTC, they had the center of the flare path at 4.6 km East of them at 18:22:28.9 UTC. So the geometries were virtually the same (with a predicted brightness of mag. -7.7 for Grimbergen, versus -7.5 for me), they having the flare maximum 20.9s earlier in time than me. What a coincidence!
I observed one pass of Lacrosse 4 (two good images, yielding 4 positions), and two of Lacrosse 5 (3 images, half of the points dropped because of too faint trail ends, hence 3 positions).
Lacrosse 5 (05-016A, #28646) did its "disappearance trick"again at both passes. During the first pass it did it at 17:30:44 UTC, while the camera was open for its second exposure, resulting in the image below. The true end of the trail at the end of the exposure should be at the right of the star near the trail end: it is at the left in the image, as the satellite dropped below the imaging treshold in brightness before the end of the exposure. The drop was rather fast.
A few tens of seconds after it, I could see the satellite as a very faint object (mag. +4 to +4.5) with the naked eye (before the drop in brightness it had been +2). A third image exposed between 17:31:46.1-17:31:56.8 UTC shows a very faint trail after some image manipulation (see below)
Lacrosse 5 did the same trick again during a second pass. This time it disappeared some 5 seconds before my camera opened, at 19:13:15 UTC.
Highlight of the evening was a splendid magnitude -7.5 flare by Iridium 03 at an altitude of 44 degrees and azimuth 28 degrees (north-northeast) at 18:22:50.8 UTC.
(click image to enlarge)
The image above was shot from the street in front of the almshouse complex (it was just too low in the sky to be visible from the courtyard of the complex) with a 10.7s exposure between 18:22:47.1-18:22:57.8 UTC. The flare had a predicted brightness of mag. -7.5, and indeed must have been in that order. The center of the flare path was 4.8 km West of me (while the Iridium satellite was over Denmark, at 785 km altitude and a range of 1069 km north-northwest of me).
Chance had it that the people from Grimbergen observatory in Belgium (Philippe Mollet et al.) located 135.9 km south of my location, observed the same flare from the same Iridium. While I had the center of the flarepath at 4.8 km West of me at 18:22:50.8 UTC, they had the center of the flare path at 4.6 km East of them at 18:22:28.9 UTC. So the geometries were virtually the same (with a predicted brightness of mag. -7.7 for Grimbergen, versus -7.5 for me), they having the flare maximum 20.9s earlier in time than me. What a coincidence!
I observed one pass of Lacrosse 4 (two good images, yielding 4 positions), and two of Lacrosse 5 (3 images, half of the points dropped because of too faint trail ends, hence 3 positions).
Lacrosse 5 (05-016A, #28646) did its "disappearance trick"again at both passes. During the first pass it did it at 17:30:44 UTC, while the camera was open for its second exposure, resulting in the image below. The true end of the trail at the end of the exposure should be at the right of the star near the trail end: it is at the left in the image, as the satellite dropped below the imaging treshold in brightness before the end of the exposure. The drop was rather fast.
(click image to enlarge)
A few tens of seconds after it, I could see the satellite as a very faint object (mag. +4 to +4.5) with the naked eye (before the drop in brightness it had been +2). A third image exposed between 17:31:46.1-17:31:56.8 UTC shows a very faint trail after some image manipulation (see below)
(click image to enlarge)
Lacrosse 5 did the same trick again during a second pass. This time it disappeared some 5 seconds before my camera opened, at 19:13:15 UTC.
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