V606 Aql (Nova Aquilae 1899) is now a dwarf nova

We found that the 1899 nova V606 Aql currently shows dwarf nova outbursts with a typical cycle length of 270 d and amplitudes of ~1.5 mag using Public Data Release of Zwicky Transient Facility observations. The low mass-transfer rate in quiescence has been suggested to explain the large eruption amplitude (Tappert et al., 2016), and the present detection of dwarf nova outbursts supports this interpretation. The transition to the dwarf nova state more than 100 yr after the nova eruption gives credence to the hibernation scenario. The absolute magnitude estimated from dwarf nova outbursts suggests that V606 Aql should have been a fast nova and the presence of high excitation lines in quiescence would be explained by the presence of a massive white dwarf.