Monday, August 13, 2012

CBERS 2B flash pattern

click image to enlarge

Last night I set up the camera with a Tamron 2.8/17-50mm lens set at f3.2/17mm to run automatically (using an Aputure timer), in order to catch some Perseids.

AS part of the image series, I captured a satellite showing a regular flash pattern. The top image above is a stack of 7 images of 20s each, showing the repeated flashing (including a brighter flare).

It turned out to be CBERS 2B (07-042A) which was launched from China on 19 September 2007 as the third Chinese-Brazilian Earth Resources Satellite. It ceased operations in June 2010.

By measuring the positions of the flashes and relating these to a recent TLE, I was able to determine the flash pattern. It is a combination of two series: one with flashes each 23.7s (series a), and another one (which includes the bright flare) with flashes each 47.4s (series b). The latter is the double of the series a period. The sequence of flashes is a-a-b-a-a-b-a-a-b but the b-flashes are not nicely in the middle of the a-series flashes.

click diagram to enlarge

The two series probably relate to different reflective surfaces. The flashes from series a are conspicuously orange, while those from series b are bluish-white.

click image to enlarge

As can be seen on the CBERS website, the satellite body itself is wrapped in orange insulation foil, suggesting the orange flashes could be reflections from the satellite body. The bluish-white flashes could be from the solar panels. The satellite would then rotate once each 94.8 seconds during which 2 solar panel flares and 4 body flares (4 sides of the cubus) can be seen.

CBERS 2B was not the only satellite captured flaring this night: I'll report on the other later. Amongst others, Envisat was seen flaring again.

Perseids

I indeed captured some meteors as well: 7 Perseids and one sporadic meteor. Here is a nice Perseid:

click image to enlarge

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