TZ Cyg Type: LB AAVSO lightcurve (2020 ) AAVSO lightcurve (index) These are slow, irregular variables of late spectral types (K, M, C, S); as a rule, they are giants. This type is also ascribed, in the GCVS, to slow red irregular variables in the case of unknown spectral types and luminosities. AAVSO Legacy Long Period Variable Programme