This is the edited and processed result of a three hour astrophotography session at the top of the Shap Road, north of Kendal, Cumbria on the evening of 15 February 2013.
Each frame in the video is a large file jpeg (12MP) on a Nikon D90 exposed for 13 seconds at ISO 6400, using a 28mm lens at f/4. I took a total of 323 frames at 4 frames per minute. They are joined and played at 10 frames per second, making the video 150x normal speed.
Asteroid 2012 DA14 is only 30 metres across, and is heading away from the Earth having approached to within 28,000 kilometers. For the whole of the shoot, it was invisible to the naked eye (magnitude 7+ by this time) and moving across the sky at about one degree of arc (that’s about twice the visual diameter of the moon) per minute.
The forecast clear skies turned to clouds, the fog spread from Kendal, the motor drive on my equatorial mount failed, it was about minus 5 celcius and I had forgotten my down jacket, hat and gloves. Apart from that everything went quite well! It was pitch dark throughout. The orange clouds are reflection of urban light, only showing because of the long exposure, wide aperture and high film speed setting.
2012 DA14 is the dot moving from bottom right to top left of the dark panel. I had no idea I’d succeeded in catching anything until I put the video together back home.
Processing details (Photoshop):
-The dark panel is an area where I eliminated all data below a certain threshold. That’s a quick and easy way of reducing the skyglow.
-For each frame in the dark panel I then isolated the asteroid in a small disc-shaped layer. I maximised the contrast within that disc, then increased its brightness to match its background to the surrounding dark panel background, effectively making the disc disappear and increasing the brightness of the asteroid.
Nothing has been cloned or otherwise added to the original data.