Alert Notice 384: Outburst of GK Persei

September 24, 2008: As reported in AAVSO Special Notice #125, the cataclysmic variable GK Persei appears to be entering another outburst. The object began a slow rise on or about 2008 September 10 UT (JD 2454719.5), rising nearly one magnitude above its typical quiescent level of m(vis) = 13, to near m(vis) = 12.2 at present (2008 September 24 UT, JD 2454733.5). This rate of brightening is typical of past outbursts, and suggests a rise to full outburst may occur soon. However, this activity comes much sooner than expected based on past intervals between outbursts, and the last outburst (2006 December 5, JD 2454075) reached a much fainter maximum than normal -- about m(vis)=11.5, more than one magnitude fainter than the typical m(vis)=10.5-10.0. Observers are asked to closely follow GK Persei at all wavelengths during the current outburst, however it may evolve. Both visual and filtered CCD photometry are strongly encouraged.

The most recent visual (M. Komorous) and V-band CCD (D. Lane) made around 2008 September 24.2 UT (JD 2454733.7) have GK Persei around m(vis) = 12.2 to 12.3.

GK Persei (AUID 000-BBG-044) is located at the following J2000 coordinates:

RA: 03 31 12.00 , Dec +43 54 15.0

Charts for GK Per may be plotted using VSP: http://www.aavso.org/vsp

Please promptly submit all observations to the AAVSO via WebObs.

Thanks to all observers who have reported GK Per in outburst and who have submitted observations thus far!

Clear skies, and good observing,

Matthew Templeton
AAVSO

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