[BAA Comets] 2P/Encke

[Shanklin, Jonathan D.]

Sorry for the delay in actually sending this to the list - the original message sent on August 1 was bounced when the BAA system was off line.

Comet 2P/Encke has the largest number of apparitions with visual observations of any comet in the BAA records, with extant records going back to 1951.  The BAA observations are broadly consistent with no change in absolute magnitude over the last 60 years, though this does not say anything about changes in the shape of the light curve.

The comet is coming into view in the morning sky, and could be within visual range, although its light curve suggests that it is often brighter after perihelion than it is before.  This apparation favours northern hemisphere observers prior to perihelion and it could be a binocular object in the dawn sky in early November.  Normally these circumstances do not atract many observers, however the early risers will benefit from a view of 2012 S1 (ISON), which could be getting within naked eye range.  2P/Encke remains in conjunction as it fades post perihelion.  The Section web page will keep you updated on the likely magnitude and details of any observations.

Electronic observations can now be tied in well with visual observations, thanks to the work of Roger Dymock in establishing a consistent reduction process.  See http://www.britastro.org/projectalcock/CCD%20Astrometry%20and%20Photometry.htm for details, and note that DSLR images can also be reduced.  All imagers should give this technique a go, as it produces total magnitudes in ICQ format that can be used for photometric analysis in conjunction with the visual observations.  The users of robotic telescopes have the advantage of not needing to get up early to make their observations!

Hopefully we can get an extended pre-perihelion light curve by merging electronic and visual observations.

I look forward to receiving your observations.

Jonathan Shanklin
Director, Comet Section

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