November comets
WHEN: 1-15 and 28-30 November
There are two reasonably bright comets on view this month: 38P/Stephan-Oterma and 46P/Wirtanen. Of the two, Wirtanen is brighter but also the least well positioned, for the time being at least. Slowly leaving the confines of the southern constellation of Fornax, the Furnace, and slipping across the border into Cetus, the Whale, comet 46P/Wirtanen is predicted to brighten past the naked eye threshold around 8 November. As it goes it’ll pick up pace, tracking north across the night sky. It will be well positioned for northern hemisphere viewing during December. Consequently, any views of 46P/Wirtanen you manage to get during November can be considered good training for next month’s bright dash across the heavens. At its peak, 46P/Wirtanen is predicted to reach mag. +3.8.
The low declination of Fornax will make locating 46P tricky this month. Also, although the comet is brightening, the Moon will cause problems, its glare creating a very efficient filter to block out the diffuse comet. However, the Moon will slip out of the way right at the end of November and it should be possible to spot 46P/Wirtanen on the starting blocks ready for its race north.
If you find the low altitude of 46P/ Wirtanen challenging, 38P/StephanOterma should prove less of a problem. Admittedly this comet is notably dimmer, starting the month off at mag. +9.4 and brightening to just +9.2 by 11 November, a value it holds for the rest of the month. But this comet is really well located for UK viewing, tracking to the east of the outline figure of the twin Pollux in the constellation of Gemini, the Twins.
At this level of brightness, 38P is best suited for telescope viewing with a low-power eyepiece. However, depending on the concentration of the comet’s head, increased magnification is always worth a try – just use small magnification jumps.
The comet crosses the midpoint of the imaginary line between mag. +3.5 Wasat (Delta (b) Geminorum) and mag. +3.6 Lambda (h) Geminorum at 00:00 UT on 5 November. It then continues to track northeast passing very close to the Eskimo Nebula, NGC 2392, during the nights of 8/9 and 9/10 November. It’s closest to the planetary nebula during the morning of 9 November. This is a great opportunity if you’re into astrophotography, the Eskimo being ranked as a mag. +10.1 object not too dissimilar to the comet. 38P/Stephan-Oterma also lies close to mag. +3.6 Kappa (g) Geminorum on the night of 17/18 November.
The comet was last at perihelion on 26 August of this year and geometrically will be at its closest to Earth in January of next year when current predictions have it as a 10th magnitude object fading to 11th.