More flares by GOCE!

After my observation of GOCE (09-013A), ESA's Gravity field and steady state Ocean Circulation Explorer, mildly flaring at 19 November (see here and here), I observed it flaring again on two other occasions: November 25 and November 26th.

Times of these new flares were 17:14:43.6 UTC (Nov 25) and 17:10:25.8 UTC (Nov 26). The November 25th flare was again of about +2.5 magnitude. The November 26th flare had cloud interference.

Below are two images of the November 25th flare (one full, in negative to show the very faint non-flare part of the trail; and a detail of the flare part), and the resulting brightness profile. FWHM of the flare peak is ~0.4s.

click images to enlarge

click diagrams to enlarge

The observation of the flare of the 26th was hampered by clouds. In fact, I only just managed to photograph the satellite at culmination through a temporary gap in the cloud cover. Still, the image (see below) clearly shows it flaring again, quite similar to how it did the evening before:

click images to enlarge

Note that these flares are probably cases where my observing locality was not that near to the central flare path. In fact, the theoretical flare path for the solar panel that probably caused these two flares of the 25th and 26th was over the UK, not the Netherlands.

I have to wait untill I have the opoortunity to observe a flare when the theoretical center of the flare path is closer to my location. Earliest opportunity, weather willing, is next Sunday evening.

Altering tumbling period of the USA 144/Misty-2 decoy (1999-028C)

In August I used a series of photographs to determine the tumbling period of 99-028C, the enigmatic USA 144/Misty-2 "Decoy" (see here).

As the tumbling period of this object is known to alter, I am repeating the experiment. I still need some additional nights to construct a full curve: but the partial curve obtained from the November 19 observations (6 images) already shows a clear change compared to August:

click diagram to enlarge

The sinusoid is for a period of 62 seconds, which compares well to a very similar period visually determined by Ted the same night. It is nice to see the two results coming out so similar.

Back in August the period was 71 seconds. A change of 9 seconds in 3 months time.

In the diagram above, the greyed data points are data from when the trail was very close to both edges of the FOV. Their absolute levels have suffered from lens vignetting, so I scaled them to show that the trend of these points at least is similar to the trend of the period determined from the other four images. The black data points are raw, unaltered data from the latter images.

Yesterday's GOCE flare modelled

After measuring the image I obtained of yesterday's GOCE flare, I determined the flare time to be 17:40:34.9 UTC (Nov 19).

Using Simone Corbellini's excellent Visual SAT-flare Tracker 3D software I found the following observational geometry:

---------------------------------------------------
SAT ID #34602 (09013A) GOCE
ORIENTATION TYPE #4: V-Sun ROTAX-DEC: 0 ROTAX-RA: 0
NUMBER OF SURFACES: 1
M#01 - 19/11/2009 17h40'34" - UM1 >>> .8839;77.1618;1
---------------------------------------------------

Note that the angle sun-craft-observer is close to zero (0.9 degree): sun, observer and craft are on one line.

In below graphic representation from Simone's software, the green line is the observed flare path over Earth's surface:

click image to enlarge

Knowing that the spacecraft has a fixed attitude towards the sun (see the ESA website), and Octagonal shape (meaning reflective surfaces at angles 22.5 and 67.5 degrees available), I find the following theoretical flare model:

SATELLITE SURFACE MODEL
---------------------------------------------------
SAT ID #34602 (09013A) GOCE
ORIENTATION TYPE #4: V-Sun ROTAX-DEC: 0 ROTAX-RA: 0
NUMBER OF SURFACES: 2
M#01 - 19/11/2009 17h40'34" - UM1 >>> 0;67.5;1
M#02 - 19/11/2009 17h40'35" - UM2 >>> 0;22.5;1
---------------------------------------------------

click image to enlarge

This suggests the tilt of my observation is 10 degrees off from the nominal theoretical tilt: either the true tilt is 10 degrees different, or (and I favour that, as it is most likely) modest flaring is still visible 10 degrees on either side of the tilt axis.

In the latter case, closer approaches to the central flare path potentially might result in much brighter flares compared to yesterday's. I'll have opportunities to check that the next 3-4 days, if weather cooperates...especially the evening of 21 November might then see a potentially very nice flare for me.

Yesterday's image of the flare/glint I posted came out a bit dark after conversion to jpg. Below is a lighter version and a larger detail image.

click image to enlarge

STSS Demo 1 (USA 208) passing the Andromeda nebula

After observing it visually through the ETX-70 2 days ago (see my report here), I had some idea that the STSS Demo 2 (09-052B) and it's twin STSS Demo 1 (09-052A) were actually bright enough to be in raneg of my camera with the EF 100/2.8.

So I tried this evening, and with succes: both objects were captured. Below is one of the images, a nice picture showing the STSS Demo 1 (USA 208) passing close to M31, the Andromeda galaxy.

click image to enlarge

Some time ago I obtained the launch patches of this twin mission (STSS is an acronym for Space Tracking and Surveillance System):

Gravity Probe GOCE (Gravity field and steady state Ocean Circulation Explorer) flaring

This evening I tried, for the second time, to capture the ESA gravity probe satellite GOCE (2009-013A) on photograph. My first attempt was on the 17th during a very low pass. This time I tried a 38 degree altitude pass, while it was moving close to mu Hercules.

Much to my excitement, the attempt was succesful, thanks to an unexpected brief flare by the spacecraft due to a reflection of sunlight from probably one of it's solar panel covered sides. I observed the flare visually, estimated it at about mag. +2.5. It shows up well on photograph, the trail fading in and out. Below is the image, shot with a Canon EOS 450D + EF 50/2.5 Macro @ 800 ISO:

click image to enlarge

GOCE (Gravity field and steady state Ocean Circulation Explorer) is a European satellite with the purpose to map the earth's gravity field in high detail. Read more about it on the ESA website here.

Space Shuttle Atlantis STS-129 and the STSS Demo-2

Yesterday evening it unexpectedly cleared, in front of a storm depression. This allowed me to observe Space Shuttle Atlantis STS-129, launched the day before and on its way to the ISS.

I observed it twice: first around 16:24 UTC, in deep twilight with the sun only 6 degrees under the horizon. It made a pass culminating at 40 degrees, and was easily visible, especially past culmination. Its brightness was mag. -01 or thereabout.

The second time I observed it, twilight had ended and the sky was dark and clear. The Shuttle stayed low however, entering Earth shadow at 27 degrees altitude short after rising in the west. I made this picture with the Canon EOS 450D and the EF 50/2.5:

click image to enlarge

Next three objects were targetted with the EF 100/2.8: USA 184 and USA 179, both in Molniya orbits, and the USA 144 Decoy (99-028C).

Unfortunately, due to a human error the images came out slightly out of focus. The USA 179 and the USA 144 Decoy series were still measurable though.

At the end of the session, a telescopic observation (Meade ETX-70 at 13.5x, stopwatch and Ted's Obsreduce) was done on one of the recently launched STSS Demo objects: STSS Demo-2 (USA 209), 09-052B. It was only 1.3s early relative to Ted's latest elset.

USA 179 and 184

After a month-long absence due to amongst other a hollidays in Canada, I was able to do some observations again last Saturday evening. It was very clear (and rather cold).

Due to a social activity earlier in the evening I had missed the LEO window (which is very short this time of the year at 52 degrees latitude), so I popped the EF 100/2.8 Macro USM on the camera and targetted two Molniya objects high in the sky: USA 179 (2004-034A) and USA 184 (06-027A). The first is an SDS-3 communications satellite, the second an advanced Trumpet SIGINT and SBIRS platform.

Both objects showed up brightly on the images, USA 184 nearly stellar and USA 179 creating clear short trails. Here's a part of one of the USA 179 (2004-034A) images, a small field in Cassiopeia:

click image to enlarge

I obtained the launch patches of these two objects recently.

USA 179:



USA 184: