GK Per in outburst
AAVSO Special Notice #399March 12, 2015GK Per in outburstThe old nova GK Per (N Per 1901), which has dwarf novaoutbursts, is going into outburst, according to observations submitted to theAAVSO International Database:
2015 Mar. 06.06667 UT, 12.9 (SLH, L. Shotter, Uniontown,PA); 06.81806, 13.0 (OJR, J. Ripero, Madrid, Spain); 06.83060, 13.3 (BVE, E.van Ballegoij, Heesch, Netherlands); 06.83750, 13.1 (MUY, E. Muyllaert,Oostende, Belgium); 06.84167, 12.8 (SPK, P. Schmeer, Bischmisheim, Germany);07.02222, 12.5 (Shotter); 07.81250, 12.4 (Muyllaert); 07.82153, 12.0 (Ripero);07.83125, 12.4 (Schmeer); 07.84900, 12.3 (PYG, G. Poyner, Birmingham, England);07.87850, 12.3 (GGU, G. Gilein, Noordwijk, Netherlands); 08.02690, 12.226 CV+/-0.010 (UJHA, J. Ulowetz, Northbrook, IL,171 obs 08.02690-.11524);08.07363, 12.093 CV +/-0.008 (Ulowetz);08.11524, 12.254 CV +/-0.010 (Ulowetz);08.82292, 12.0 (WKL, K. Wenzel, Grossostheim, Germany);08.85100, 12.1 (Poyner); 09.01667, 12.0 (Shotter); 09.02920, 12.1 (BRJ, J.Bortle, Stormville, NY); 09.78750, 12.2 (KWO, W. Kriebel,Schierling/Walkenstetten, Germany); 10.01880, 12.1 (Bortle); 10.02845, 12.051CV +/-0.009 (Ulowetz, 154 obs 10.02845-.10884); 10.03060, 12.2 (KMA, M.Komorous, London, ONT, Canada); 10.06788, 11.960 CV +/-0.011 (Ulowetz);10.10884, 12.191 CV +/-0.089 (Ulowetz); 10.78417, 12.152 V +/-0.004 (DUBF, F.Dubois, Zillebeke, Belgium,143 obs 10.78417-.84714);10.81736, 12.0 (Muyllaert);10.81965, 11.870 V +/-0.003 (Dubois);10.82361, 11.8 (Ripero);10.83190, 12.0 (Gilein);10.84714, 12.022 V +/-0.004 (Dubois);11.02780, 12.1 (Komorous);11.77778, 12.1 (Wenzel);12.01320, 12.1 (Bortle);12.02780, 12.2 (Komorous);
GK Per has dwarf nova outbursts about every 18-24 months,although the interval can vary quite a bit. It is difficult to predict howbright this outburst may be; the brightness and duration of recent GK Peroutbursts has varied substantially.
Its last outburst was almost exactly two years ago, inMarch 2013, when it reached V=12.2 and was brighter than V=12.8 for only 17days, according to the AAVSO International Database (AAVSO Special Notice#343). That outburst is the faintest and shortest on record since July 1978.
Its previous outburst was three years earlier, in March2010, when it reached V=9.7 and was brighter than V=12.8 for at least 100 days(the exact number of days is unknown because GK Per returned to minimum duringits seasonal gap), according to the AAVSO International Database. That outburstis the brightest on record since the nova outburst in 1901. The 2010 outburstbrightness may be related to the long interval to the 2013 outburst, as well asto the interval between the 2008 and 2010 outbursts, which was six monthsshorter than usual. (The September 2008 outburst reached V=12.1 and wasbrighter than 12.8 for about 30 days.)
Please monitor GK Per and report your observations to theAAVSO, using the name GK PER.
Coordinates:R.A.03 31 12.01 Dec. +43 54 15.4 (2000.0)
Charts for GK Per may be created using the AAVSO VariableStar Plotter (http://www.aavso.org/vsp).
This AAVSO Special Notice was compiled by Elizabeth O.Waagen.
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ATel #7217 on 13 Mar 2015; 04:32 UT【Optical Spectroscopy of GK Per (Nova Per 1901) during the 2015 Outburst】
On 2015 March 6.84 UT, Dubovsky (VSNET-ALERT 18388) and Schmeer (VSNET-ALERT 18389) discovered that the old nova and intermediate polar cataclysmic variable GK Per (Nova Per 1901) was in outburst at a magnitude of 12.8. GK Per undergoes dwarf nova outbursts on time scales of 1-2 years with optical amplitudes of 2-3 magnitudes that last several months. Previous outbursts were recorded in 2006 (ATEL #965) and 2010 (ATEL #2466) as well as a weak outburst in 2013. An analysis of the optical and X-ray outbursts of GK Per was recently presented by Šimon (2015, A&A, 575, A65).
We obtained an optical spectrum (range: 398-685 nm; resolution 0.3 nm) of GK Per during the current outburst on 2015 March 10.326 UT with the 2.4 m Hiltner Telescope (+OSMOS) of the MDM Observatory on Kitt Peak. Our spectrum shows strong, single-peaked emission lines of the Balmer series of hydrogen; He I 447.1, 471.3, 492.1, 501.5, 587.5, and 667.8 nm; He II 468.6 and 541.1 nm; and N III 464.0 nm. In addition, the absorption lines of Na I D are prominent. He II 468.6 nm emission is quite strong with an equivalent width of 1.2 nm and with an intensity ratio with respect to Hβ of about 1.8. The resolution-corrected FWHM of He II 468.6 nm and Hα are about 650 km/s and 507 km/s respectively.
A comparison of our spectrum of GK Per with the spectra presented by Reinsch (1994, A&A, 281, 108) as well as a spectrum (range: 320-670 nm; resolution 0.5 nm) obtained in quiescence by some of us in October 1995 at the 4.5 m MMT typically show that the intensity ratio of He II 468.6 nm to Hβ is about 0.4-0.5. These spectra also exhibit absorption lines arising from the K2-type secondary star which contributes about 1/3 of the total light of the system at optical wavelengths (see Reinsch 1994 and references therein). Our spectrum obtained during the outburst shows no evidence of the secondary star since the system is brighter at the present time. Additional photometric, spectroscopic, and X-ray observations are encouraged during the current outburst.
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