Comet 73P-Schwassmann-Wachmann 3 (2006), a Jupiter family comet, was discovered by two German astronomers Arnold Schwassmann and Arno Arthur Wachmann on May 2, 1930. This comet was their third and final discovery so it was named comet Schwassmann-Wachmann 3. It has an orbital period of 5.36 years.

During its 1995 appearance the comet began to disintegrate and broke into 5 large components or nuclei that were labeled 73p-A, B, C, D and E. Recently astronomers reported some 40 fragments as the comet continues to break up, with C, D, G, and R being the brightest.

In its next return in 2001 the comet was brighter than expected and three of the nuclei seen in 1995 were observed again, with component C being the brightest.

In 2006, it is not clear how many of the nuclei will be visible, but component C is expected to be the brightest. However in early April component B at magnitude ~9.3 is now brighter than C at magnitude ~9.7.

As of mid-April, both components B and C were reported visible in 10x40 binoculars from a dark sky site, with C being brighter than B and showing a hint of a tail. Through telescopes both B and C are showing tails, with component G appearing fainter. Components G and R are located near component B.

The comet will be at perihelion on June 7th, 2006 and will make its closet approach to Earth on May 12th, 2006 when it is expected to be around magnitude 4.0 or a little brighter. However the Moon will be full on May 13th, so it would be best to observe the comet either in the morning sky before its closest approach, or in the evening sky after its closest approach.

When Comet 73P-Schwassmann-Wachmann 3 makes its closet approach to Earth it will be only around 7.5 million miles away. The last time a comet passed close to the Earth was Comet IRAS-Araki-Alcock in May 1983. It passed only 2.9 million miles from the Earth and came closer to Earth than any comet since 1770. Because of this its motion was visible through the eyepiece within seconds, which was impressive to observe.

Below are some recommended observing windows and maps to help locate the comet. I provide also information on the altitude of the comet for observers living at or near 40 degrees north latitude, which would include cities such as Boston, New York, Washington DC, Chicago, Milwaukee, St. Louis, Des Moines, Wichita, Denver, Casper, Salt Lake City, Boise, San Francisco, as well as observers living at or near 30 degrees north latitude, which would include cities such as Jacksonville, Atlanta, Memphis, New Orleans, Tulsa, Houston, Albuquerque, Tucson, and Los Angeles. Note that depending upon where the observer lives the start of astronomical twilight can vary from the values given below.

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April

By the beginning of April the comet is expected to be around magnitude 10.0. The Moon will be at first quarter on April 5th, and full on April 13th, so it would be best to observe it before dawn during this time. For example, on April 5th the comet at the start of astronomical twilight a little before 5:00 AM will have an altitude of 56° from 40 degrees north latitude. At 30 degrees north latitude at the start of astronomical twilight around 5:45 AM the comet will have an altitude of 66°. Interference from moonlight will occur after April 9th.

Another observing window in April will occur between 16th and the end of the month, when it will be possible to observe the comet in the evening and morning sky, with the Moon being at last quarter phase on April 21st and new on April 27th. For example, before the Moon rises on April 16th at 11:00 PM the comet will have an altitude of 43° from 40 degrees north latitude. At 30 degrees north latitude the comet will have an altitude of 36°.

By midnight on April 27th the comet will have an altitude of 55° from 40 degrees north latitude. At 30 degrees north latitude the comet will have an altitude of 43°.

At the end of April the comet will have an altitude of around 73° from 40 degrees north latitude at the start of astronomical twilight a little after 4:00 AM. At 30 degrees north latitude the comet will have an altitude of around 71° at the start of astronomical twilight little after 5:00 AM.

Here is a chart showing the path of 73P-Schwassmann-Wachmann 3 components B and C from April 8th, 2006 to May 8th, 2006.

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May

By the beginning of May the comet is expected to be around magnitude 6.0. However interference from moonlight will be start to become more of an issue in early May, with the Moon at first quarter phase on May 5th, and full Moon on May 13th, when the comet makes its' closest approach to the Earth. So it would be best to observe the comet in the morning sky after the Moon has set and before the onset of astronomical twilight.

Here are sketches I made of Comet Schwassmann Wachmann components B and C on: April 21st, 2006 , on April 30th, 2006, on May 7th, 2006, and on May 17th, 2006.

For example on May 2nd the Moon sets around 12:30 AM. The comet will have an altitude of 55° from 40 degrees north latitude at the start of astronomical twilight a little after 4:00 AM. At 30 degrees north latitude the comet will have an altitude of around 71° at the start of astronomical twilight little after 5:00 AM.

On May 8th the Moon sets around 3:37 AM at 40 degrees north latitude when the comet has an altitude of 73°, and astronomical twilight will not begin until around 3:57 AM. The Moon sets around 4:00 AM at 30 degrees north latitude when the comet will have an altitude of 73°.

Here is a chart showing the path of 73P-Schwassmann-Wachmann 3 components B and C from May 6th, 2006 to May 16th, 2006. Note that Comet Pojmanski will be visible near the top of Cassiopeia.

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Here is a chart showing the path of components B, C, G, and R from May 9th to May 16th. As of May 9th components B and C are around magnitude 6. Component G has faded after splitting into many small fragments, but component R has brightened recently.

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Here is a chart showing the path of components B, C, G, and R from May 15th to May 24th before the start of astronomical twilight at 40 degrees north latitude. The comet will appear higher in the sky at 30 degrees north latitude at the start of astronomical twilight. Recently component B had an outburst and is currently brighter and larger than component C.

Charts prepared using SkyMap Pro version 9.