A faint comet discovered in Virgo last November is slowly brightening as it approaches the Sun. Comet Boattini (C/2007 W1) has now become dimly visible to the unaided eye for skywatchers in the Southern Hemisphere.
While not exactly a barn-burner, and showing little or no sign of a tail, Comet Boattini is now in Hydra and low in the western sky after sunset. When the bright Moon leaves the evening sky next week, Southern Hemisphere skywatchers will get a better view of this visitor.
As reported on IAU Circular 8945, issued yesterday by the Central Bureau for Astronomical Telegrams (CBAT) at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, Alexandre Amorim of Florianopolis, Brazil, found the comet to be magnitude 7.3 on April 30th in 10 x 50 binoculars; its coma appeared to him about 12 arcminutes in diameter. By May 8th, David Seargent in Cowra, NSW, Australia, called it magnitude 6.4 to the naked eye.
On June 15th Comet Boattini swings 41° south of the Sun and enters the morning sky. Then on June 24th it reaches perihelion, 0.85 astronomical unit from the Sun and 0.24 a.u. from Earth. Northern Hemisphere observers will get their chance to see Comet Boattini in early July, when it crosses Taurus and enters Cetus. But by then it is expected to be fading from 7th to 8th magnitude.
This object is not to be confused with another Comet Boattini, C/2008 J1, which is much fainter (magnitude 14) and currently in Vulpecula.
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Roger W. Sinnott
Sky & Telescope