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:
Canon 60D (set at 3200 ISO) with
a standard lens, a Sigma 18-200 at 200 mm f/6.3. Exposures of 5 s, sRAW
format. The large field allowed to spot the asteroid while it emerged
from the trees.
A telescope, Newton Maccagnan
310 mm f/5 with a fast planetary camera, a I-nova Pla-mx black and
white, so that I can gather really a lot of short exposures. The
obtained image scale is 0.74"/pix. Exposures of 0.1s and framerate of
about 9 fps on average.
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:
images, with the trail of the asteroid
videos, both with the asteroid moving in the field, or the asteroid manually tracked
photometry, obtained analyzing the tracked series of images
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.
Photometry
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.
