169P/NEAT: A Comet or an Asteroid?
Faulkes Telescope observations
The comet 169P was first observed by the Near-Earth Asteroid Tracking
system. In order to observe this comet we had to figure out if it was
possible to view it from Faulkes Telescope South, a 2m reflecting telescope
which is used for research as well as for use by school students around the
world over the internet. We found where this comet was predicted to be using
the
Minor Planet
Center. Since 169P is such a bright object, we were able to use a red
filter on some of our observations to provide a clearer image. We made five
observations of the comet and could clearly see its orbital movement.
At 1400 hours on Monday 25th January we took control of the
Faulkes Telescope South in Siding
Spring, Australia. With the help of
David and
Tolis, we found that our exposure
time should be at most 20 seconds, because the comet was moving quite
fast. We decided 10 seconds exposure was long enough due to the comet's
bright magnitude. We managed to take 5 photographs of the comet before moving
on to a new observation. In order to distinguish between a star and our
comet, we had to take more than one observation of the same position and then
compare the images to see if any of the supposed stars moved. In our images
it was very clear where 169P was as it moved a great deal.
An animation showing the movement of 169P. Images obtained using the Faulkes
Telescope South, operated by Las Cumbres Observatory.
169P was first thought to be an asteroid and was given the designation 2002
EX12. After obtaining our images we made astrometric and photometric
calculations and realised why this had happened.
The easiest distinction to make between comets and asteroids is that
asteroids are point source objects and comets are not. Most comets have
comas, a visible, fuzzy atmosphere surrounding them. We compared the FWHM
(Full Width Half Maximum) of our comet to the FWHM of the surrounding stars
as we know that stars are point source objects. We found that our comet did
have similar FWHM to the stars, showing no detectable coma and explaining why
it was first classed as an asteroid.
169P is the
parent body to the
alpha Capricornids meteor shower. The shower can be seen from July
15
th to September 11
th but is best observed at the
beginning of August. The shower has the reputation of producing some of the
brightest meteors of the major showers, with the average magnitude being
estimated as about 2.2. There was confusion over the shower's parent body for
over 50 years.
We had three more observing sessions booked for the week and hoped to make
more observations of 169P/NEAT. Only two of these sessions were with Faulkes
Telescope South and unfortunately both were cancelled due to bad weather. We
did however get to observe five other asteroids using Faulkes Telescope
North, including 21 Lutetia, an unusual main belt asteroid which will be the
first M-Type asteroid passed by the European space probe
Rosetta.
We had a wonderful time learning how to use the telescope and appreciate all
the time that David, Tolis and everyone else at the Observatory spent helping
us understand what we were doing.
Alison Hoy and Ronan Smyth
2010 January 29th
More astronomical projects with the Faulkes Telescopes
Last Revised: 2010 February 2nd
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