Alert Notice 649: Dwarf nova outburst of GK Per (N Per 1901)

Note: The outburst suspected of possibly beginning in early October did not occur. Please continue to observe.  -  Elizabeth O. Waagen, 29 October 2021

GK Per MAY be beginning an outburst; please continue to observe.  -  Elizabeth O. Waagen, October 4, 2021

Although the 2018 outburst of GK Per has been over for some time, ongoing good coverage is requested.  -  Elizabeth O. Waagen, 13 April 2020

August 24, 2018: The old nova GK Per (N Per 1901), which has dwarf nova (minor) outbursts, appears to be going into outburst, according to observations reported to the AAVSO. Recent observations include:

2018 Aug. 21.04030 UT, 13.0 (E. Muyllaert, Oostende, Belgium);
21.187, 12.83 (G. Hurst, Basingstoke, UK, remotely using the Open University COAST C-14 telescope (Tenerife));
22.08819, 12.9 CV (K. Wenzel, Grossostheim, Germany);
23.05140, 12.8 (P. Dubovsky, Kolonica, Slovakia);
23.10069, 12.5 visual (Wenzel);
23.11875, 12.6 (P. Schmeer, Saarbruecken-Bischmisheim, Germany);
23.13125, 12.45 CV (Wenzel);
24.156, 12.16 V (Hurst);
24.260, 12.22 V +/-0.04 (R. Modic, Willoughby, OH);
24.30690, 11.8 (M. Komorous, London, ONT, Canada);

GK Per has dwarf nova outbursts about every 18-36 months, although the interval can vary quite a bit and some intervals can be longer than three years. It is difficult to predict how bright this outburst may be; the brightness and duration of GK Per outbursts have varied substantially over the past 16 years.

Its last outburst was over three years ago, in March 2015 (AAVSO Special Notice #399), with GK Per reaching visual magnitude 9.8/V=9.9 and remaining brighter than V=12.8 for at least 70 days, according to the AAVSO International Database. It was obscured behind the sun while in decline, and had returned to minimum by 2015 June 20.

Other outbursts since 2000 are:

- March 2013, reaching V=12.2 and remaining brighter than V=12.8 for only 17 days (AAVSO Special Notice #343). That outburst is the faintest and shortest on record since July 1978.

- March 2010 (AAVSO Special Notice #198), reaching V=9.7 and remaining brighter than V=12.8 for at least 100 days (the exact number of days is unknown because GK Per returned to minimum during its seasonal gap). That outburst is the brightest on record since the nova outburst in 1901. The 2010 outburst brightness may be related to the long interval to the 2013 outburst, as well as to the interval between the 2008 and 2010 outbursts, which was six months shorter than usual.

- September 2008 (AAVSO Alert Notice 384), reaching V=12.1 and remaining brighter than 12.8 for about 30 days.

- December 2006 (AAVSO Special Notice #26), reaching V=11.3 in the second of three distinct peaks (this outburst was a very unusual one) and remaining brighter than 12.8 for 92 days.

- September 2004, reaching V=10.6 during a slow and complex rise and remaining brighter than 12.8 for about 100 days.

- March 2002 (AAVSO Alert Notice 294), reaching V=10.2 and remaining brighter than 12.8 for about 65-70 days (it was at 12.7 when it became unobservable).

In the 1990s, its outbursts occurred in July 1992 (AAVSO Alert Notice 159), February 1996 (AAVSO Alert Notice 219), and February 1999 (AAVSO Alert Notice 254).

Observations of all types (visual, CCD, DSLR, PEP) and in multiple bands, as instrumentation permits, are strongly encouraged throughout this outburst.

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

Charts with a comparison star sequence for GK Per may be created using the AAVSO Variable Star Plotter.

Please submit observations to the AAVSO International Database using the name GK PER.

AAVSO Forums: GK Per is the topic of the AAVSO Time Sensitive Alerts forum thread

and the AAVSO Novae forum thread

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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