variable star designation

Current variable star designation can be considered a variant of Bayer designation. Current procedures are to do the first of these available:

1. Use the Bayer designation if the star has one.
2. Use capital letters R through Z with the constellation.
3. Use letter-doublets with first letter R and above, and second letter equal to first letter and above, with the constellation (RR to ZZ).
4. Use letter-doublets without any J and with first letter A through Q and second letter equal to the first letter and above, with the constellation (AA to QZ).
5. Use V335, V336, V337, … with the constellation.

Numbering begins with 335 because the letter combinations cover 334 designations. The system's complexity is due to repeated efforts to accommodate larger numbers of known variable stars as observation has improved. Example designations: T Tauri, DQ Tau, GG Tau, HL Tau, V1216 Sagittarii.

Note that there are nova-specific designations for nova events and recurrent novae, but the star may well have the above type of variable star designation as well, either due to the nova itself (especially a recurrent nova) or due to other observed variation.