COMET D/1819 W1 (BLANPAIN): NOT DEAD YET

We present a new observation that conclusively reveals the cometary nature of the planet-crossing asteroid 2003 WY25 through the detection of a weak optical coma. This observation strongly supports the identification of 2003 WY25 with the lost comet D/1819 W1 (Blanpain) made previously on the basis of dynamical similarity. It also shows that 2003 WY25 is a continuing but weak source of particles for the Phoenicid meteor stream with a mass injection rate into the stream of ~10^-2 kg s^-1. This is too small to supply the estimated 10^11 kg stream mass on any plausible timescale, suggesting that the mass injection into the stream may be episodic and/or involve additional sources. We estimate a nucleus radius near 160 m and find that, consistent with estimates for other meteor streams, the ratio of the nucleus mass to the stream mass is of order unity. We find that 2003 WY25 is the smallest cometary nucleus yet observed.