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AAVSO Special Notice #198: Possible Outburst of GK Per AAVSO HOME > publications > special notice

AAVSO Special Notice #198

Possible Outburst of GK Per
March 8, 2010

Special Notice #198
March 9, 2010

The old nova (1901) and x-ray source GK Per may be going into 
outburst. Reports beginning late on 2010 March 6 UT show it 
brightening from its minimum visual magnitude of about 13.1 
to 12.3-12.4. 

When GK Per went nova in 1901, its disk was destroyed. 
Eventually the disk was re-established, and dwarf nova-like 
outbursts were observed. After many years of quite similar-
looking outbursts about 1100-1300 days apart, rising to about 
visual magnitude 10.1 in 24-30 days, and lasting 53-73 days, 
the last two outbursts were very different, with the September 
2004 outburst coming only 940 days after the preceding 
outburst, taking over 60 days to rise to a maximum of 10.6, 
and lasting about 100 days, and the December 2006 outburst
coming about 810 days later, rising only to magnitude 11.5 
with oscillations to 12.2 before returning to minimum about 
100 days after outburst. The current probable outburst is 
occurring about 1180 days after the last outburst, so it may 
show more typical outburst behavior, or it may do something 
completely unexpected. Close monitoring is extremely 
important.

Our assistance has been requested by Dr. Phil Evans, 
University of Leicester, England, who is observing GK Per 
with the Swift satellite and has requested Target of 
Opportunity (ToO) time on RXTE. Dr. Evans writes:

"I have an approved Swift ToO which will observe it 3 times 
a day for the next 4 days (looking for the change in X-ray 
characteristics) and then for 6 ks twice a week thereafter. 
It chose a bad time of year to go off so will be too close 
to the Sun for Swift from early April. I've also put in a 
ToO request with RXTE and we'll see what happens.

"The AAVSO archive on this object is stupendous and anything 
your observers can do to make it even better will of course 
be gladly received by the whole CV community."

Visual and CCD observers are urged to monitor GK Per closely
and submit observations to the AAVSO International Database. 

Recent observations of GK Per reported to the AAVSO 
International Database include:

MAR 01.8600 UT, 13.0, G. Poyner, Birmingham, England; 
04.8050, 13.0, P. Schmeer, Bischmisheim, Germany;
04.8167  13.1, G. Hurst, Basingstoke, England, via baavss-alert;
04.8420, 13.1, Poyner;
04.9170, 13.03 V, E. van Ballegoij, Heesch, Netherlands;
05.0139, 13.0, M.Komorous, London, Ontario, Canada;
05.8410, 12.9, C. Allen, Farjestaden, Sweden;
06.0896, 12.8, J. Bortle, Stormville, NY;
06.7986, 12.9, Allen;
06.8010, 12.7, Schmeer;
06.8243  12.7, Hurst);
06.8698, 12.34 V, van Ballegoij;
06.8740, 13.0, Poyner;
07.0299, 12.6, Bortle;
07.0507, 12.6, G. Chaple, Townsend, MA;
07.7708, 12.4, K. Pukero, Tavastila, Finland;
07.7950, 12.4, Schmeer;
07.8390, 12.3, Poyner;
08.0201, 12.5, Komorous;
08.0264, 12.4, Bortle;
08.0292, 12.5, Chaple;

Coordinates: R.A. 03:31:12.01 Dec. +43:54:15.4 (2000.0)  

Charts for GK Per may be obtained from the following URL:
http://www.aavso.org/observing/charts/vsp/index.html?pickname=gk%20per

Observations should be reported as GK PER.

An AAVSO Observing Campaign on GK Per is being created by Dr.
Matthew Templeton.

Good observing!

Elizabeth O. Waagen, Senior Technical Assistant

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