USNO Magnitudes versus calibrated

Field RA = 20h38.3m DC = -18°20'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +2.54 -0.160 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = +0.30
Error cancels for Magnitude 15.9

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.25 +0.023 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.08
Error cancels for Magnitude 10.7

For any comment, contact Jean-Claude PELLE