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GOCE MODEL AND FLARES



GOCE FLARE MODEL - 12 January 2010


Download the Workspace for the prediction of GOCE (NORAD 34602, 2009-013A) flares: 
GOCE Flare Workspace
    Download



The provided workspace embeds two GOCE models. The first model (satellite name GOCE) will show the centre of the flare generated by the main surfaces, which have angle 93.5 and tilt of 22.5 and 66.5Theoretically, the correct angle should be 90 since the satellite has attitude control that is supposed to keep the satellite's longitudinal axis within the orbital plane and parallel to the velocity vector. However, so far, observations have shown that the maximum of the flare is always reached when the angle is nearly 93.5 ( 0.3), as if the attidute control exhibited a fixed "error" of 3.5 (satellite pointing 3.5 out of the orbit plane toward the sun).

Another interesting characteristic of such flares is that they are faintly visible also when the flare centre falls very far from the observer, but always at the time at which the reflection would be generated by a surface with 
angle of 93.5 ( 0.3). This may suggest that the satellite has rounded surfaces, something like a cylinder, rather than flat surfaces that shape its octagonal cross section.

The satellite observer
Dr. Marco Langbroek, who captured several GOCE flares, investigates the results in his station blog web site (http://sattrackcam.blogspot.com/), where a good explanation of the geometry and more data are provided as well.

To predict also the time of the faint flares (distant flares), a second model has been embedded into the provided workspace (satellite name GOCE 93.5) defining several plane surfaces with different tilt angles but with a common fixed angle of 93.5

Do not forget to update the TLE of the GOCE satellite before using the model (copy and past the lastest TLE into the edit box of the Satellite frame and press the UPDATE button)


Goce Flares
Fig.1 - Example of flares generated by the second model, which shows the reflection of surfaces with different tilts and angle of 93.5.


OBSERVED GOCE FLARE From North Italy


5th of January 2010

The satellite flared in the sky region defined  by the following IOD points:

34602 09 013A 0000 F 20100106170944280 18 35 0300427+397775 57
34602 09 013A 0000 F 20100106170944679 18 35 0301052+404094 57

which correspond to the time: 5/01/2010 17:09:44.5
0.5 s (UTC)
and to the following reflecting surface:

Angle: 93.5 
0.5
Tilt: 43.11

10th of  January 2010


IOD point of the flare:

34602 09 013A   0000 F 20100110165231030 16 35 0550333+267885 57

which corresponds to the time: 10/01/2010 16:52:31
0.5 s (UTC)
and to the following reflecting surface:

Angle: 93.4 0.3
Tilt: 22.58

The magnitude of the flare was about 0 (the satellite appeared red, like
Aldebaran but more bright at the flare maximum).


Goce Flare 10/12/2010
Fig.2 -
Example of flares generated by the first model, which shows the flare centre for both the 22.5 and 66.5 tilted surfaces.

OBSERVER'S COORDINATES

Latitude:  45.488 N
Longitude:  8.557 E


By Simone Corbellini