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The Discovery of Comet Lovejoy
By TERRY LOVEJOY
The discovery of C/2011 W3 happened
on the morning of November
28th (local time) as part of
my routine comet survey. On this
morning I imaged 200 separate
fi elds, taking three exposures per
fi eld, between declination –35°
and –55° and right ascension 9h
00m and 13h 30m. The patrol is
set up so that exposures for the
same fi eld are separated by 9 minutes,
making it easy to detect the
movement of comets by “blinking”
the images in rapid succession
on a computer monitor.
When examining the images
the following evening, I immediately
noticed a diff use object
moving rapidly eastward in Centaurus.
At fi rst I thought it was a
refl ection from Gamma Centauri,
which was a little outside my fi eld
of view. But the object’s motion
was uniform, compelling me to
make follow-up observations.
On the morning of November
30th there were enough breaks
between the clouds for me to take
several short exposures. I was
elated to fi nd a diff use object at
almost the exact location I had
projected from the November
28th positions! Because I was
now quite certain this was a new
comet, I asked other observers for
independent confi rmation.
At fi rst there was disappoint-
Appearing as little more than a smudge near the center of these three
November 27th (Universal Time) discovery images, the comet’s motion
was suffi cient to warrant follow-up observations.
Australian amateur Terry Lovejoy with the imaging gear used for his
latest comet discovery. The cooled monochrome QHY9 CCD camera
and 8-inch Celestron Schmidt-Cassegrain telescope are set up for f/2
HyperStar imaging. His previous two ground-based comet discoveries
were made with a DSLR camera and telephoto lens.
ment. On November 30th two
fellow Australian amateurs failed
to see the comet — Andrew
Pearce searched visually with
his 8-inch refl ector, and Michael
Mattiazzo did not capture it with
a Canon 300D DSLR and 300mm
lens. I also heard from Alan
Gilmore at New Zealand’s Mount
John Observatory who could not
perform follow-up observations
because of high winds. The following
night, however, Gilmore
and Pam Kilmartin imaged the
comet with the observatory’s 1.0-
meter refl ector. The comet was
offi cially announced on December
2nd by the Central Bureau
for Astronomical Telegrams as
C/2011 W3 (Lovejoy).
This was my third groundbased
comet discovery in addition
to 11 I found by examining images
from the SOHO satellite. While
I was focused on fi nding Kreutz
Sungrazing comets in the SOHO
images, my ground-based survey
was not. So I was very pleased
that this latest discovery turned
out to be a sungrazer!
Observers on the ground weren’t the only ones getting a
spectacular view of Comet Lovejoy as it rose above the horizon.
Astronaut Dan Burbank aboard the International Space Station
captured this image of the comet on December 21st. The green
layer above the blue twilight glow is due to oxygen atoms about
60 miles (130 km) above Earth’s surface. NASA / DAN BURBANK
SkyandTelescope.com May 2012 41
TERRY LOVEJOY (4)