2012 DA14 flyby
15 February 2013
by Lorenzo Comolli

The night of 15 Feb 2013 a small asteroid of about 50 meters made a very close flyby with the Earth at 27743 km from surface (for more info, read wikipedia). Imaging this flyby was a challenge because of the very high speed in the sky, up to 0.8 °/min. In my very small field of view, only nearly 10 seconds were needed for the asteroid to cross the full field.

I selected to use two setups:
Location: my observatory, in Tradate, Italy, 45°42'44,4" N  8°54'26,1" E, 305 m height, MPC code B39.
I observed from 20:27:53 UT (first 60D image) to 21:37:19 UT (latest telescopic image).
The sky was quite bad, due to a haze that limited the visible stars to about mag. 3. SQM readed about 18.5 mag/arcsec^2, but transparency was very poor.
I've obtained:

Videos and Images

Video of first sight of the asteroid coming out of the trees. Canon 60D and 200 mm f/6.3. Click on 1080p for a better quality (YT is quite bad in this case).

Video of the asteroid in the telescope field at TRUE SPEED. First two clips are with the asteroid moving in the field, the last (and longer) is made by keeping centered the asteroid in the telescope (by manual tracking with handpad). Newton Maccagnan 310 f/5, I-nova Pla-mx at 0.74"/pix and 10 fps. Click on 480p for best quality.

From 20.43.18 UT to 20.43.26 UT (only 8 s). Other data in the image.

With the data collected during the tracking of the asteroid, I tried to analyze the photometric variations during short time periods. I don't know if this is of any interest, but I tried and here is the result.
First, the light curve shows clearly the dimming due to the object going away from Earth. That's about 0.12 mag in 6 minutes.
Then the FFT spectrum of the data show a periodic behaviour with a period of about 65 s. I've confirmed this with 3 other image sequences, even if they are gathered in less ideal conditions.
Measurements obtained with Iris and analyzed with Matlab.

Please contact me for any comment: comolli@libero.it

HTML Editing and Publishing by Lorenzo Comolli. Email me at comolli@libero.it.
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