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:

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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
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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
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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
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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

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.