USNO Magnitudes versus calibrated

Field RA = 20h41.3m DC = -18°09'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +2.29 -0.152 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = +0.17
Error cancels for Magnitude 15.1

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +0.09 -0.001 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.07
Error cancels for Magnitude 78.6

For any comment, contact Jean-Claude PELLE