P/2002 EX12 (NEAT)
First picked up in March 2002 by the NEAT survey it was designated as
2002 EX12 and categorised as asteroidal.
Three years later Brian Warner at the Palmer
Divide Observatory, Colorado started a photometric run on it and on
the first night saw that it had a straight tail, estimated as up to 90" long on images taken
the next night on 29 July
2005.
Alan Fitzsimmons using
the 2.0-m Faulkes Telescope North at Haleakala also reported a 30"
long tail on images taken 29 July 2005 and further reported that on May 10
and May 14 2005 it did not show any obvious tail in images taken
with the 2.0-m telescope and the 3.5-m New Technology Telescope. (Details
from IAUC
8578 and Brian Warner's CALL
website)
When discovered in 2002 March the comet was 9 months past perihelion, 2
AU from Earth, 3 AU from the Sun, receding from both and fading at 19th
magnitude. After discovery it was identified on pre-discovery images back
to 1989 March,
In late July 2005 when first reported as a comet it was 0.19 AU from Earth
and 1.1 AU from the Sun, just a week away from its closest approach to the
Earth (0.147 AU) and due at perihelion (for the first time since discovery)
on 17 September 2005 at a
distance of just 0.6 AU from the Sun. It is in a quite eccentric orbit
(e=0.77) with a period of 4.2 years, taking it out to 4.6 AU at aphelion,
about 0.6 AU inside the orbit of Jupiter.
The animation shows the comet over a period of 8 days through its
closest approach to Earth on 2005 Aug 6th. On Aug 6th and 7th the straight
tail can be seen extending about 7' and the outer coma can be seen as a
very diffuse glow in most frames, extending up to 2' diameter on Aug 8.9 UT. Total exposure time varies for each frame (see details on
animation) and the last frame (Aug 9.9 UT) was cut short due to
obscuration by trees.
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