USNO Magnitudes versus calibrated

Field RA = 20h33.0m DC = -18°41'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +2.13 -0.149 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = +0.04
Error cancels for Magnitude 14.3

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.35 +0.024 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = -0.02
Error cancels for Magnitude 14.7

For any comment, contact Jean-Claude PELLE