USNO Magnitudes versus calibrated

Field RA = 19h01.4m DC = +11°38'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.73 -0.113 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = +0.15
Error cancels for Magnitude 15.3

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.99 -0.140 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.03
Error cancels for Magnitude 14.2

For any comment, contact Jean-Claude PELLE