Alert Notice 807: GK Per undergoing dwarf nova outburst

January 3, 2023

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The old nova (N Per 1901) GK Per is undergoing a dwarf nova outburst, the first observed since 2018.

Observations of all types (visual, CCD, DSLR, PEP) and in multiple bands, as instrumentation permits, are strongly encouraged throughout this outburst and for at least 30 days after GK Per returns to minimum.

The most recent observations submitted to the AAVSO International Database (AID) show GK Per at V magnitude 11.302 +/- 0.004 on 2023 Jan. 02.72312 UT (F. Dubois, Zillebeke, Belgium).  The multicolor light curve below from the AID shows the behavior of GK Per prior to and during the outburst to date. 24 observers worldwide contributed the 175 observations (2022 November 15 - 2023 January 3) shown in this light curve. GK Per may have reached maximum for this outburst, but it is too soon to be certain.


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 20+ years.

The current outburst is occurring more than 4 years after the last observed outburst, making the interval among the longer ones in recent decades. Its last observed outburst took place in August 2018 (AAVSO Alert Notice 649), when GK Per reached visual magnitude 10.1/10.23 V and remained brighter than V=12.8 for 66 days, returning to minimum in October 2018.

Other observed outbursts since 2000 are:

- 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.

- 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).

Coordinates: 03 31 12.01 +43 54 15.5 (from VSX page for GK Per)

Charts with comparison stars for GK Per may be created using the AAVSO Variable Star Plotter (VSP).

Please submit photometric and visual observations to the AAVSO International Database using the name GK PER. Spectroscopic observations should be submitted to the AAVSO Spectroscopy Database.

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


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