Since PEP_BVI_v3.1.xls, the spreadsheet fully reduces the check star sample, so it is easier to compare its magnitude with the catalogue value. Of course it is not very accurate, as we take only one sample for the check, compared to three for the variable. I’ve collected all the reduced check star magnitudes for 2024, averaged the values an determined the sd. I’ve selected the checks that I’ve measured at least 10 times that year:
HD 198639 (check of alf Cyg): V=5.049±0.004 (24 times) catalogue: V=5.058±0.011
SAO 33657 (check of miu Cep): B=7.894±0.026 (12 times) catalogue: B=7.90
SAO 33657 (check of miu Cep): V=6.895±0.018 (12 times) catalogue: B=6.88
HD 223165 (check of rho Cas): B=5.997±0.013 (14 times) catalogue B=5.984
HD 223165 (check of rho Cas): V=4.880±0.008 (14 times) catalogue V=4.869±0.007
HD 223165 (check of rho Cas): R=4.324±0.006 (10 times) no catalogue value
HD 223165 (check of rho Cas): I=3.833±0.008 (10 times) no catalogue value
HD 1239 (check of V566 Cas): V=5.721±0.005 (10 times) catalogue V=5.729±0.010
I notice that the uncertainty becomes bigger as the star becomes fainter. This is no surprise, as I am approaching the limit of my setup at those faint magnitudes.
The source of the magnitudes (including the uncertainties, when listed) in the starparm files is the GCPD.
So my measurements agree with the catalogued values, so this gives me (more) confidence that our PEP photometry yields very good results indeed, at least when we measure when the conditions are good.