I had a look at the offsets of USNO-A2.0 magnitudes versus standard R and B. The calibration dataset includes Arne Henden's V1315 Aql data, data for the open cluster Berkeley 82, the two relevant GSPC sequences, and a few others. For the two overlapping POSS-I plates, the offset of USNO-A2.0 'mb' from standard B is close to zero, and in field 513 (east of the nova), the R offset is also essentially zero. The field immediately west of the nova has an offset of 0.4 mag. for R (USNO-A too bright). For the moment, of course, one can use Tycho V and B-V, as long as the errors reported in the Tycho catalogue are < 0.05 mag. for each. \Brian