174P Echeclus in outburst

For an update on this outburst see here.

The unusual Centaur comet 174P Echeclus is currently undergoing one of its brightest ever outbursts. Also known as minor planet 60558 this object moves in an orbit which has a perihelion of 5.8 AU, an aphelion of 15.5 AU and a period of 34.9 years. It last came to perihelion in 2015 April and it is currently moving outwards. At the start of December it was 7.3 au from the sun and around mag 17.

On December 8th Brian Skiff reported that images he had taken on the previous day showed the comet to be at least 4 magnitudes brighter than expected. Jean-Francois Soulier and Richard Miles confirmed the outburst with 0.20m and 2.0m telescopes respectively. At first the object was stellar but it is now showing a distinct coma which can be detected in small instruments as shown in this image from Tim Haymes. Tim has used Astrometrica to measure the Point Spread Function (PSF) of the comet and of a nearby star and the comet is clearly “fuzzier” than the star. The magnitude of the comet is now around mag 13 or so.

The comet is conveniently placed in the early evening sky and the Comet Section would be pleased to receive your images and photometry of this unusual object.

The BAA image archive for 174P is here. Compare an image taken before the outburst with one taken just afterwards.

An observation of the comet by Tim Haymes showing that it has a broader PSF than a star.

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