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Video astrometry of Near-Earth Asteroid 2014 JO25

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About this observation
Observer
Alex Pratt
Time of observation
19/04/2017 - 00:37
Object
Asteroid 2014 JO25
Observing location
Z92
Equipment
C11 f/10 @ f/3.3
Watec 910 video camera
IOTA-VTI GPS time inserter
Tangra software
Exposure
0.32s, 0.16s and 0.08s integrations
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The clouds parted for an hour or so to allow me to record a dozen videos of the flyby of Near-Earth Asteroid 2014 JO25 on the night before its closest approach, when it was around mag 13.

Exposure times of 0.32s were used at 23:50 UT (MPC predicted mag 13.6) and reduced to 0.08s from 00:28 UT as the sky quality improved and the asteroid achieved a higher altitude. Sky conditions deteriorated after 01:00 UT (MPC mag 13.3) and I was clouded out by 01:30 UT.

Tangra plate-solves ~200 video frames from each 1 minute recording and it computes a least squares fit to the movements in RA and Dec. The asteroid had a sky motion of about 140"/min (2.3"/sec), so it's a balancing act of using a long enough exposure to record the asteroid and obtain a good number of field stars for astrometry, yet short enough to minimise the movement of the target body across the pixels. Luckily 2014 JO25 was passing through rich star fields.

Astrometric positions will be derived from the videos and submitted to the MPC.

The latest radar images show the asteroid looks like a bi-lobed peanut.

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