Recurrent Nova M31N 2008-12a: Liverpool Telescope observation of the waning 2017 eruption

ATel #11149; M. J. Darnley (LJMU), M. W. Healy (LJMU), M. Henze (SDSU), S. C. Williams (Lancaster)
on 9 Jan 2018; 21:28 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)

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The tenth consecutive annual eruption of the recurrent nova M31N 2008-12a was discovered on New Year's Eve 2017 (ATel #11116). A sub-set of the follow-up observations have subsequently been reported in ATels #11117, #11118, #11121, #11124, #11125, #11126, #11130, #11133, #11134, and #11144. Comprehensive multi-wavelength studies of previous eruptions have been published in Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b.

Here we report a set of Liverpool Telescope (Steele et al. 2004) IO:O observations during the 'final decline' phase (t>8 days; see Darnley et al. 2016) of the 2017 eruption. Each of the four reported observations consists of 3×450s exposures taken in dark conditions at airmass ≤1.16 with median seeing of 1''.

 
Date (UT)              Photometry 
2018 Jan 09.823±0.008  u'=21.69±0.05 
2018 Jan 09.840±0.008  r'=21.81±0.03 
2018 Jan 09.856±0.008  B= 22.05±0.01 
2018 Jan 09.872±0.008  V= 21.98±0.03 

The optical light curve evolution of the 2017 eruption has, to date, followed the light curve templates derived from the 2013, 2014, and 2015 eruptions (Darnley et al. 2016. Therefore, we can conclude that the eruption occurred at 2017 Dec 31.3±0.1 UT. As such, these observations were taken approximately 9.5 days post-eruption.