USNO Magnitudes versus calibrated

Field RA = 12h33.2m DC = +37°58'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.18 -0.018 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.44
Error cancels for Magnitude -10.1

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.58 +0.027 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = -0.20
Error cancels for Magnitude 21.4

For any comment, contact Jean-Claude PELLE