University Lowbrow Astronomers

P/Schwassmann-Wachmann (73P) C, B, G, R + 20 more

Comet Alert

by Mark S Deprest
Printed in Reflections: May, 2006.

That’s right folks I’m reporting on a comet ... (big surprise). Just in case you haven’t been following the Astro-news lately, here is a short summary on this comet’s journey through our solar system.

Discovered in 1930 as P/73 Schwassmann-Wachmann 3 and later renamed. Its orbital period was determined to be 5.36 years and its absolute magnitude (m1) = 11.5. However, after its initial discovery it was not recovered again until 1979 and was missed again in 1985 but recovered once more in 1990. During these two apparitions the comet’s light curve remained rather steady, but in August of 1995 the comet’s nucleus split and its absolute magnitude brighten to 5.5. After this initial split 3 components were observed, the main component C, along with two fainter pieces labeled A & B. In 2001 along with the main component C, two new components were observed and listed as B & E. There is some debate concerning component E and just where it came from, but the A component has not reappeared and is thought to be totally sublimated.

Enter 2006 and a very close approach (0.076au) to Earth, a great opportunity to observe the weakly bound nature of comets. So far this apparition has not disappointed anyone in a comet’s ability to be anything but predictable. First, 20+ components have been recovered as of now (most of them extremely faint) 4 of these have become bright enough to be seen telescopically and at least 2 of these binocular objects. The main component C has held together and is brightening slightly below its predicted line and should come close to un-aided eye visible at closest approach. Component B, a very volatile piece has been going through some major outburst and at one point became brighter than C. However, in recent days it has become very diffused visually and split into 2 very distinct pieces (you can see some photographs at AFAM (Associazione Friulana di Astronomia e Meteorologia) and CARA (Cometary Archive for Amateur Astronomers)). Components G & R although much fainter than the two components described above, have also been somewhat volatile and brighten sharply a couple of weeks ago. G & R have since steadied out and appear to be following their respective light curves.

Below: the light curve for the C, B, G and R components of P/73 Schwassmann-Wachmann 3 (you may need to scroll to the right to see the entire light curve).

The over all fate of this comet on this pass is still very uncertain, so my suggestion is to get out and observe it as often as possible, but especially in the night of May 7th-8th, when the C component will pass directly in front of M57, the Ring Nebula (see the finder charts below).

Below: Comet P/Schwassmann-Wachmann (73P) tracks of the 4 brightest components from May 1st through May 11th 2006 (you may need to scroll to the right to see the entire chart).

Below: Component C on the night of May 7th-8th as it passes in front of M57, the Ring Nebula (you may need to scroll to the right to see the entire chart).

Charts created using Guide 8.0

Note: On May 7th at 21:30 EDT this component will only be 4 degrees above the northeastern horizon. However, by 23:00 it will be almost 18 degrees up and should be a spectacular sight!

So, find an observing site with low horizons and clear skies, get your binoculars, your telescopes, and / or your cameras ready, this is going to be a sight to remember!


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