Monday, August 4, 2008

Outburst of Comet 199P/Shoemaker

Prompted by an alert of Gustavo Muler about a possible outburst of 199P/Shoemaker, we perfomed some follow-up of this comet: we can confirm his initial observation of 2008, Aug. 3.9, that this comet is experiencing a bright phase. Co-adding of 30 unfiltered exposures, 60 seconds each, obtained on 2008, August 04.16 through a 0.25m, f/3.4 reflector + CCD (near Mayhill, NM) reveals the comet as an obvious featureless star-like object of magnitude 14.7N.

Our stack is available here (details on image):

Image enhancement techniques show also the presence of a fain external coma, about 25 arcsec in diameter. The total magnitude m1 calculated for an aperture of 25 arcsec in diameter is about 14.6; the afrho parameter (proxy of the dust abundance within the coma) has been found to be about 800 +/- 100 cm (however it must be said that for an outbursting comet, the afrho characterization is not very meaningful because we are lacking a steady state coma behaviour).

Anyway, this is our afrho plot:

According to Minor Planet Center "dates of last observation of comets" website, 199P was last observed by Gustavo Muler (MPC #J47) at magnitude 17.9N on 14.92 July 2008.

by Ernesto Guido and Giovanni Sostero

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