USNO Magnitudes versus calibrated

Field RA = 19h23.1m DC = +04°58'

Fig 1. USNO 'B' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +0.97 -0.072 * B_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'B' = -0.05
Error cancels for Magnitude 13.4

Fig 2. USNO 'R' Magnitude Error f(Magnitude)
Red = USNO - Calibrated
Yellow = Best Fit: Y = +0.45 -0.030 * R_cal
Y vertical Tick = 0.1 magnitude
Offset for Magnitude 14.0 'R' = +0.03
Error cancels for Magnitude 14.9

For any comment, contact Jean-Claude PELLE