USNO Magnitudes versus calibrated

Field RA = 18h28.2m DC = +25°18'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +2.98 -0.215 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.04
Error cancels for Magnitude 13.8

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.41 -0.092 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.12
Error cancels for Magnitude 15.3

For any comment, contact Jean-Claude PELLE