Comet 46P/Wirtanen

By Richard Harvey

46P/Wirtanen is a small short-period comet with a current orbital period of 5.4 years. It was discovered on January 17, 1948, by the American astronomer Carl Wirtanen, and expectations were high for the comet’s 2018 visit.

Many astronomers hoped for naked eye brightness reminiscent of 1997’s Hale Bopp, (which I remember seeing easily over the Albert Memorial from Queens Square, Wolverhampton. Hard to believe that was over twenty years ago!). Unfortunately, comet 46P/Wirtanen appeared fainter than hoped. At its closest approach, on the16th December 2018, it was only visible in binoculars from semi-rural sites. But even so, it gave amateur astronomers a fantastic, rare chance to study a comet.

Wolvas observatory dome with 8" Skywatcher Reflector
Wolvas observatory dome with 8″ Skywatcher Reflector

With the new society observatory still being finely tuned, (and hopefully open to members to visit in January 2019), we’ve temporarily installed my 8” Skywatcher Reflector in the dome, and it was through this that I tracked the comet in the early hours on Monday 17th December. I took some very basic shots, with my Canon 750 DSLR attached directly to the scope with a T-mount.

The photos show the comet moving N N/W over a period of one hour twenty minutes. The comet was approx 11,580,000km away when I took these shots (only one second exposure time).

When you spend an evening observing, very few telescopic objects change in real time. Jupiter’s moons can change, and very often you see one disappear, or reappear from behind the disc. I’ve also seen lunar shadows creep across flat areas near mountainous regions near the terminator of the moon, and there’s oculations and eclipses, but even so, it’s rare to see something move in real time, astronomically.So it was a real treat to map, watch and image the comet’s path among the stars of Taurus on that Monday morning.

Comet Wirtanen 16/17th Dec - 1
Comet Wirtanen 16/17th Dec – 1
Comet Wirtanen 16/17th Dec - 2
Comet Wirtanen 16/17th Dec – 2
Comet Wirtanen 16/17th Dec - 3
Comet Wirtanen 16/17th Dec – 3

The comet will also be in the skies through January 2019.