USNO Magnitudes versus calibrated

Field RA = 20h07.3m DC = +36°05'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
 Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.61 -0.110 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = +0.06
Error cancels for Magnitude 14.6

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
 Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.47 -0.083 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.30
Error cancels for Magnitude 17.7