SIMBAD references

High-quality CCD-based UBVRI photometry is presented for ∼45, 000 stars distributed among 60 different fields centered on the celestial equator and at δ ~ -50°. This photometry has been calibrated to the standard Johnson UBV and Kron-Cousins RI systems via observations of the UBVRI standard stars presented in the works of Landolt. The majority of the stars in our photometric catalog fall in the magnitude range 12 ≲ V ≲ 22 and in the color range -0.3 ≲ (B - V) ≲ 1.8. Each star averages 67 measures in each UBVRI filter from data taken on 250 different photometric nights over a period of ∼6.5 yr from two different telescopes. Our final photometric database effectively extends the UBVRI standard star network defined by Landolt to much fainter magnitudes and increases the number density of stars within pre-existing standard fields. Hence, these new, fainter standards serve as suitable calibrators for investigators who employ either small or large-aperture telescopes for their observational projects.