USNO Magnitudes versus calibrated

Field RA = 15h26.2m DC = +08°18'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +0.59 -0.080 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.53
Error cancels for Magnitude 7.4

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +0.70 -0.056 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = -0.07
Error cancels for Magnitude 12.7

For any comment, contact Jean-Claude PELLE