USNO Magnitudes versus calibrated

Field RA = 20h09.8m DC = +15°58'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
 Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.89 +0.013 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.71
Error cancels for Magnitude 68.6

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
 Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.18 -0.002 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = -0.21
Error cancels for Magnitude -73.8