Another GOCE flare

Yesterday evening started very clear, but ended cloudy. Nevertheless I was able to bag several objects: the Lacrosses 2 & 3, the NOSS 3-4 Centaur rocket, GOCE flaring, and the HEO objects USA 179 and USA 184.

GOCE (the European Gravity field and steady state Ocean Circulation Explorer) made a zenith pass, zipping close to M31 at mag. +4 to +5 and then flaring briefly to mag. +2 at 17:24:23.15 UTC. It was nice to watch. GOCE is in a very low orbit and moves very fast: the flare almost looks like a meteor to the eye.

The flare was caused by the 67.5 degree panel and the time yields a flare angle of 93.6 degree and tilt of 51.9 degree. The 93 degree angle is consistent for all GOCE flares I so far observed (theoretically, that angle should be 90 degrees, i.e. at the moment of culmination when the sun-observer-satellite flight direction makes a square angle). The miss distance to the theoretical central flare path (quite large in this instance: some 175 km!) doesn't really seem to matter with regard to the flare brightness: they always come out at +2 to +3 (even when, as in this case, the tilt is off from 67.5 degree by over 15 degrees).

Below is the image, the derived brightness profile (edit - please note that the time stated in the upper left corner of the diagram is wrong: I inadvertently mentioned the end of the exposure here instead of the flare peak time), and the observing geometry. Note how the flare peak is slightly asymmetrical, the descending branch is slightly steeper.

click images to enlarge

Off to a good start: a GOCE and a Lacrosse 2 flare

2010 started off well with a very clear evening of January 1st. I observed GOCE (09-013A), the Lacrosses 2 & 3 (91-017A & 97-064A), the tumbling NOSS 3-4 Centaur rocket (07-027B), and the HEO objects USA 179, 184 and 200.

I was treated to two small flares: one by GOCE (09-013A) and one by Lacrosse 2 (91-017A).

The GOCE flare was a mild one to about +3, at 17:32:58.0 UTC. It was caused by the 67.5 degree panel. The time of the flare (accurate to 0.1s) yields an angle of 93.2 and tilt of 66.3 with a nominal mis distance to the theoretical flare path (angle 90 degrees, tilt 67.5 degrees) of 19.4 km at the time of observation (and closest approach to 17.1 km 1.2 seconds earlier at 17:32:56.8 UTC).

So far, all the GOCE mild flares I observed were with an angle ~93 degrees. The distance to the nominal flare path of this one was much less than for the three flares previously observed by me, but that doesn't seem to have much influence on the observed flare brightness: they were all around +3 magnitude.

Below are the picture, the derived brightness profile, and a depiction of the flare path geometry based on Simone Corbellini's Visual Sat-Flare Tracker 3D software.

click images to enlarge

Unexpectedly, I also captured a brief (<0.5s) flare/glint by Lacrosse 2 (91-017A) at 17:56:58.4 UTC. Below is the image and the resulting brightness profile:

click images to enlarge

Clear skies continue!

The series of clear frosty skies is continuing here. Following my last report on December 22nd observations, I have been able to do more observations on the 26nd, 27th and 29th, plus a number of deep-sky guided astrophotography sessions.

But first the satellites. Captured targets on these nights were Lacrosses 3 & 4 (97-064A & 00-047A), the NOSS 3-4 rocket (07-027B), which is still slowly variable, and the NOSS 3-2 duo (01-040A & C).

The latter NOSS duo made a very nice pass across the Pleiades yesterday evening:

(click image to enlarge)

Yesterday, I slao shot this photograph of the open star cluster M35 in Gemini. It is a stack of 65 x 10s images, taken with the Canon EOS 450D piggyback on my Meade ETX-70. Lens was the same EF 50/2.5 (at F2.8) I use for the satellite imagery, and ISO was set at 1200.

(click image to enlarge)

Near the edge of the original, M1, the Crab Nebula, actually shows up as well:

(click image to enlarge)

I used an image of the Pleiades shot the evening of the 25th to glean some more indications of the astrometric positional accuracy of the EF 50/2.5 lens. The stacked image contains several asteroids up to mag. +12 (10 Hygiea, 21 Lutetia, 94 Aurora, 182 Elsa and 264 Libussa), and by measuring these in Astrometrica (highly accurate astrometric software I use for my asteroid searches in NEAT data) and comparing to the predicted positions, it turns out that the positional deviations are typically within 5" (that is arcseconds).

That is the same accuracy AstroRecord (the wide field astrometry software I use for my satellite images) indicates from the fit to the reference stars. So it is the timing uncertainty which is the main cause of uncertainty in my satellite positions.

Bright Keyhole Satellites

A late report on my observations of Wednesday evening 12 March.

After a strong gale in daytime the sky cleared in the evening, although fields of clouds still came and went. A near first quarter moon in the sky was no real nuisance.

Several objects were observed: NOSS-es 2-3 and 3-4 and the NOSS 3-4 rocket, plus two KeyHoles: USA 129 and USA 186.

USA 129 (96-072a) was bright again just after it emerged from eclipse. I observed it telescopically and obtained a photograph, yielding 4 positions in total. The visually obtained data dn the photographically obtained data agree well. The image is below and shows it near Castor and Pollux:

(click image to enlarge)

The other Keyhole observed, USA 186, flared short and bright while the camera was open:

(click image to enlarge)

96-072A was 0.5s early, 05-042A 0.5s late, 07-027A on-time, 07-027C perhaps some 0.3s early (I might have been a tad "fast"with the stopwatch on this one though), and the rocket 07-027B was 1.6s late. The 96-029 C & D components were both 0.4s early, the E component 0.2s early.

Yesterday evening (Saturday 15 March) the sky was too hazy to do serious satellite observations. I did shoot some nice moon images though. Below is an image of the craterland on the southern hemisphere (click it to see it at full screen, full resolution), plus a mosaic image constructed from 3 partial moon images. They were taken through my Meade ETX-70 with my Canon Digital Ixus 400 compact camera.

(click images 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)

Another -8 Iridium flare

Bright Iridium flares never are a bore, and the summer season with its long twilight at my latitude has plenty of them.

Last night at 22:56:24 UTC (Aug 4) I observed Iridium 21 (99-032B) flare brilliantly to mag. -8 in Ophiuchus. Like 31 July's Iridium 74 flare (which occurred in roughly the same sky position), it visually had a yellowish colour.

(click image to enlarge)

It was a beautifully clear, warm night. In addition to Iridium 21, I also observed a nice bright pass of ISS, reaching mag. -3. Another object that never bores. On the classified front, I observed IGS 1B (03-009B) and the NOSS 3-4 Centaur rocket (07-027B) again.

While imaging IGS 1B, certain noises through an open window nearby reminded me that on a beautiful night like this, some other people also engage in their own particular pleasurable hobbies too... ;-)

As I was very tired, I stopped after observing and photographing the Iridium flare.

NOSS 3-4 Centaur rocket brightness variation

Last night (3-4 August) I observed the NOSS 3-4 Centaur rocket stage (07-027B) again over a large part of its trajectory. I obtained a number of images (yielding 10 positions), and they nicely show the varying brightness of the rocket stage due to its tumbling. It can be well seen in below series of snapshots, which were taken at approximately 1 minute intervals:

(click image to enlarge)

note added 05/08: the variation is not in each sub-image, but between the images. Basically, the sequence for these four is: picture #1 bright trail; picture #2 faint trail; picture #3 bright trail again; picture #4 faint trail again.

Apart from 07-027B, I also observed IGS 1B (03-009B) and a mag. -0.5 flare of Iridium 74 (98-032D). Around the time of the Iridium flare however, cirrus clouds moved in and I stopped observing.

The NOSS 3-4 centaur rocket (07-027B): a nice new object

June 15 2007 saw the launch of NRO's NOSS 3-4 satellites. They belong to the new US Navy twin satellite constellation (the old NOSS-es were trio's) the purpose of which is to pinpoint the origin of shipping communications.

The payload couple (07-027A & C) and the last stage NOSS 3-4r Centaur rocket (07-027B) are now being tracked by amateurs. For me, the Centaur stage (07-027B) is the most interesting, as it is bright. It is also slow moving. And making zenith-passes near midnight for my station at the moment. Which all makes it a fine photographic target.

The object slowly tumbles, as is apparent from a very slow variation in magnitude. Over the course of a minute or so, it varies between mag. +4 and +1.5 on a zenith pass.

Last week I observed the object for the first time, on 3 different nights including last night (I observed a fine list of other objects from my regular observing program as well on these nights).

On the first two nights I was greatly hampered by drifting fields of cumuli but could nevertheless capture the object through gaps in the cloud cover. Last night was clear and I could follow it along a large part of its trajectory, the slow amplitude in brightness due to the tumbling being very apparent. Below three images show the object as captured on the nights of July 29-30, 30-31 and July 31-Aug 1.

(click images to enlarge)

Last night the first (out of 3) image of the object suffered from an attempted counter-intelligence attack though ;-)

Frenkie, the cat of my neighbour, joined me at the courtyard that night and started to hug me and my camera tripod in the way cats do. As a result the first image I obtained contained a wobbled satellite trail and I did not measure it. I chased away Frenkie, as lovely as he is, and shot two more images one of which is shown above.

(Frenkie is now suspected to be back at his CIA headquarters, reporting to his commander, who carefully trained him: "Meooow, mission only partly accomplished").

I also had an Iridium flare path center coming almost exactly over my house last night. It concerned Iridium 67 (98-021F) and it flared brilliantly to at least mag. -8. The flare had a distinct yellow colour.

(click image to enlarge)

The previous night also saw a nice (less bright: mag -1) flare of Iridium 64 (98-021C):

(click image to enlarge)