Tuesday, November 20, 2018
Seeing comet 46P Wirtanen from Australia
46P is a short period comet which ahas an orbital peiod of 5.4 years. This year is a particularly favourable year and the comet may become as bright as magnitude 3 (about as bright as gamma Crucis, the fifth brightest star in the Southern Cross)
The comet will pass at 0.0781 AU (~30 LD) from Earth, on 16 December 2018 making this the brightest close approach for the next 20 years.The comets magnitude might peak as bright as magnitude 3 near its December 16, 2018 closest approach.
However, although potentially bright, its fussy, diffuse nature means it will be difficult to spot with the unaided eye under suburban conditions. Even under dark sky conditions it will be a faint fuzzy dot.
The comet is currently around magnitude 6, and a reasonably easy target for binoculars, unfortunately the waxing moon will make it harder to spot for the next week or so.
Also unfortunately it is in an area pretty much devoid of useful guide stars.
At the moment the best way to find it is draw an imaginary line between Rigel and Achernar, then draw a line perpendicular to this and continue on until you reach the boxy shape that is the constellation of Cetus. then around halfway
Black and white printable binocular chart for locating comet 46P over the coming month as seen from Adelaide at 21:42 ACDST (90 minutes after sunset, basically a black and white version of the chart at the top). The circle is the approximate field of view of 10x50 binoculars.
Within a binocular distance of Upsion Ceti are the two dimmer stars nu (ν) Fornacis and mu (μ) Fornaci. The comet will form a shallow triangle with them becoming a steeper triangle over the following days.