USNO Magnitudes versus calibrated

Field RA = 16h54.4m DC = -20°26'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +2.44 -0.164 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = +0.15
Error cancels for Magnitude 14.9

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.20 -0.061 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.34
Error cancels for Magnitude 19.6

For any comment, contact Jean-Claude PELLE