2022RNAAS...6..241S

We report the discovery of a previously unknown eruption of the recurrent nova M31N 2017-01e that took place on 2012 January 11. The earlier eruption was detected by Pan-STARRS and occurred 1847 days (5.06 yr) prior to the eruption on 2017 January 31 (M31N 2017-01e). The nova has now been seen to have had a total of four recorded eruptions (M31N 2012-01c, 2017-01e, 2019-09d, and 2022-03d) with a mean time between outbursts of just 929.5 ± 6.8 days (2.545 ± 0.019 yr), the second shortest recurrence time known for any nova. We also show that there is a blue variable source (〈V〉 = 20.56 ± 0.17, B - V ≃ 0.045), apparently coincident with the position of the nova, that exhibits a 14.3 days periodicity. Possible models of the system are proposed, but none are entirely satisfactory.