Kepler Mission – Exoplanets – what’s all the fuss about? – By Stuart Atkinson
Hmmm. It’s a good question actually. Why DOES it matter that we now know some of those twinkling points of light in the night sky are circled by strange, exotic worlds? Why are astronomers spending hours and hours gazing at these distant suns, hoping to glimpse signs of planets spinning around them? And with countless problems to solve down here on Earth, why should money be spent on scanning the heavens for far-flung alien solar systems with multi-million $ telescopes, satellites and computers?
Simple. Because we have to leave Earth and find another home.
Read the full article by Stuart Atkinson, BtC collaborator, at Cumbrian Sky.
The stray light inside the telescope was sunlight scattered through baffles at two gaps around the dust cover where the pins holding the dust cover to the sunshade are located. The stray light illuminated an “arc” around the edge of the dust cover opposite the entry points. (Interestingly enough, there are some dust particles on the field flattening lenses that functioned as inverse pin hole cameras, so we actually saw reverse images of the illumination pattern inside the sunshade.) The images we first obtained were very dark at the top of the focal plane array, and became gradually lighter towards the bottom of the focal plane. We aren’t talking about much light: at most, about 12,000 photoelectrons per read were falling on the brightest edge of the focal plane. When we tilted the photometer away from the sun, we almost completely eliminated the stray sun light getting through the simple baffles in these gaps (more complex baffles could prevent the dust cover from releasing cleanly). The maximum amount of light we measured on these final images was less than about 10 photoelectrons per readout, so the light was reduced by over a factor of 1000.
We had our “first light” already with some sunlight making it in around the dust cover, but found a different attitude at which almost no light entered the telescope so that we could get a good dark frame for comparison with preflight test, and that can be used to formulate some of our calibration products. In retrospect, it’s nice to see that all 42 science CCDs and 4 Fine Guidance Sensor CCDs are responding to light as well as behaving as expected in dark frames.
As I write these words Kepler has still its sleep mask on and has been, in the last days, dreaming with the future view, with the wonders waiting in the distance, in some sort of REM as calibration tests take place.
