is a series of images I took remotely on the morning of April 18
from Mayhill, New Mexico, using the iTelescope
T11. The movie consists of sixty 12-second exposures, spanning
about 20 minutes. The field of view is approximately 22' x 16'.
The asteroid was magnitude14.5.
April 19/20 the asteroid 2014 JO25 passed near to the earth. This
event was widely observed, both visually and via imaging. During
the pass there were some problems with the sources of standard
orbital elements, which left some looking off track, but I am
happy to say that SkyTools users have reported in from around the
world that the positions from SkyTools were "spot on."
the asteroid approached, I made the series of images that make up
the above movie. The exact positions were determined from the
images and compared to those predicted by the orbital elements
from the Minor Planet Center, the ASTORB database maintained at
Lowell Observatory, and the online JPL Horizons ephemeris
generator. It was clear that the JPL elements were the most
accurate. Also, as the asteroid passed close to the earth/moon
system, the orbit would be perturbed. In other words, the orbit
would slowly change due to the gravitation effect of the earth and
moon. Normal orbital elements don't take this into account, but
the JPL system does, so I decided to use it to generate sets of
orbital elements at 12 hour intervals throughout the pass. These
were made available as part of the "Current Minor
Planets" observing list download for SkyTools users. When
multiple sets of elements are available for the same object,
SkyTools will select the one closest to the time being used. In
this way, SkyTools was able to very accurately predict the
position of the asteroid even as the orbit changed during the
user David Lloyd-Jones of Sydney Australia sent the following
comparison of his own images and the prediction of SkyTools. He
reported that, "It was exactly spot-on
and made finding the object so easy."
Own Visual Observations
invited people to join me at a local football field, where I set
up my 8-inch Dob. Finding the asteroid was easy because it would
pass near a naked-eye star in the early evening. As the twilight
faded, I pointed the scope just to the right of the 5th magnitude
star 41 Com, referring to a printed SkyTools finder chart.
the eyepiece, the asteroid was easy to spot because it made a
right-triangle with two other 11th magnitude stars. As I watched,
the shape of the triangle changed obviously in just a few seconds,
which was very cool! Below is the SkyTools eyepiece simulation of
what I saw.
that the chart above was created automatically by SkyTools,
matching my view exactly, including the sky brightness, visible
stars, and orientation.
Rare Observing Treat in Asteroid 2014 JO25
made this asteroid interesting to observe wasn't how close it
came, but how large, bright, and fast moving it was. It became brighter than 11th magnitude, which is within reach of
small (4-inch and larger) telescopes. It moved through
the sky so fast that it's motion could be seen in a high-power
as Large as Previously Thought
asteroid was discovered in 2014 via the Catalina Sky Survey in
Arizona. Initial estimates put it at about 2000 ft (650 m) in
diameter. It takes 3 years to orbit the sun. On April 19th, 2017, passed near the earth, about 4.6 times the distance between the
earth and moon. This was the closest pass to the earth for this
asteroid in 400 years, and it will not pass this close again for
another 500 years. The next known flyby of an object of this
size won't be until 2027.
on April 17, the asteroid was observed via radar using the Arecibo Observatory Planetary Radar System.
These images revealed a peanut-shaped object that is twice as large
as recent estimates, 0.8 miles (1.3 km) at its widest. It takes
about 3.5 hours to rotate once.
are some of the radar images via NASA:
Greg Crinklaw —
Amateur/Professional Astronomer and Developer of
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