USNO Magnitudes versus calibrated

Field RA = 18h48.0m DC = -20°06'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = -0.76 +0.013 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.58
Error cancels for Magnitude 59.4

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +1.32 -0.070 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.34
Error cancels for Magnitude 18.8

For any comment, contact Jean-Claude PELLE