We present optical spectroscopy and multi colour photometry of the old novae V630 Sgr, V693 CrA, V728 Sco, and V840 Oph. We show that novae stand clearly out in colour diagrams as very blue objects with an additional red component. We use the diagrams to select best candidates for the nova identifications in the hitherto uncertain cases of V728 Sco and V840 Oph, and provide spectroscopic confirmation for the latter.
展开▼
