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Detection of the First Observed Outburst of DW Cancri

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Tim Crawford

Arch Cape Observatory, 79916 W. Beach Road, Arch Cape, OR 97102

David Boyd

5 Silver Lane, West Challow, Wantage, OX12 9TX, UK

Carlo Gualdoni

22100 Como, Italy

Tomas Gomez

Lira 8, 6-A, 28007 Madrid, Spain

Walter MacDonald II

P.O. Box142, Winchester, ON K0C 2K0, Canada

Arto Oksanen

Verkkoniementie 30, FI-40950 Muurame, Finland


Received April 27, 2007; revised January 4, 2008; accepted January 7, 2008



Using data gathered by amateur astronomers from several nations, as reported to the American Association of Variable Star Observers (AAVSO), the first observed outburst of the intermediate polar DW Cancri was detected on January 25, 2007, at magnitude V ~11.36. This represented a brightening of ~4 magnitudes from both recent measurements and long term average quiescence. The outburst was of a relatively short duration, as measured from the first detection of the outburst, showing a fading of ~2.25 magnitudes in ~27 hours, and another ~1.25 magnitudes within the next ~30 hours. Follow up photometric observations show the asynchronous rotation period of the magnetic white dwarf star of this system to be 38.6 minutes, in agreement with previous studies; a strong secondary signal of ~73.7 minutes was also noted. As to whether or not the outburst was the result of disk instabilities or caused by a mass transfer event, no conclusion could be reached.

AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484