USNO Magnitudes versus calibrated

Field RA = 18h52.0m DC = -01°28'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.01 -0.077 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.07
Error cancels for Magnitude 13.1

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +0.22 -0.015 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.02
Error cancels for Magnitude 15.2

For any comment, contact Jean-Claude PELLE