The observations we reported in ATel #2166 were actually of nova M31 2009-08b, not 2009-08d. Therefore, ATel #2166 confirms the nova nature of nova M31 2009-08b...
Erratum to “Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory” [Astroparticle Physics 32(2) (2009), 89-99]