Atmospheric Refraction Correction Table Observers Height Above MSL vs. Unrefracted Altitude Above Horizon Corrections in Arc-Minutes Toward the Zenith HEIGH TEMP PRESS --- OBJECT ALTITUDE ABOVE HORIZON IN DEGREES---- Feet DegC mbars 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 ----- ---- ------ ---- ---- ---- ---- ---- ---- ---- ---- ---- ---- 0 21.0 1070.0 9.2 8.6 8.0 7.5 7.0 6.6 6.3 5.9 5.7 5.4 1000 18.6 1034.5 9.0 8.4 7.8 7.3 6.9 6.5 6.1 5.8 5.5 5.2 2000 16.3 999.2 8.8 8.1 7.6 7.1 6.7 6.3 6.0 5.6 5.4 5.1 3000 13.9 964.3 8.5 7.9 7.4 6.9 6.5 6.1 5.8 5.5 5.2 5.0 4000 11.4 929.8 8.3 7.7 7.2 6.7 6.3 6.0 5.6 5.3 5.1 4.8 5000 9.0 896.1 8.1 7.5 7.0 6.5 6.1 5.8 5.5 5.2 4.9 4.7 6000 6.4 863.3 7.8 7.3 6.8 6.4 6.0 5.6 5.3 5.0 4.8 4.6 7000 3.9 831.5 7.6 7.1 6.6 6.2 5.8 5.5 5.2 4.9 4.7 4.4 8000 1.2 800.8 7.4 6.9 6.4 6.0 5.6 5.3 5.0 4.8 4.5 4.3 9000 -1.4 771.1 7.2 6.7 6.2 5.8 5.5 5.2 4.9 4.6 4.4 4.2 10000 -4.1 742.5 7.0 6.5 6.1 5.7 5.3 5.0 4.8 4.5 4.3 4.1 11000 -6.7 714.8 6.8 6.3 5.9 5.5 5.2 4.9 4.6 4.4 4.2 4.0 12000 -9.2 687.9 6.6 6.1 5.7 5.4 5.0 4.8 4.5 4.3 4.0 3.9 13000 -11.7 661.8 6.4 6.0 5.6 5.2 4.9 4.6 4.4 4.1 3.9 3.7 14000 -14.0 636.5 6.2 5.8 5.4 5.1 4.8 4.5 4.2 4.0 3.8 3.6 15000 -16.3 611.9 6.0 5.6 5.2 4.9 4.6 4.3 4.1 3.9 3.7 3.5 16000 -18.4 588.0 5.9 5.4 5.1 4.8 4.5 4.2 4.0 3.8 3.6 3.4 17000 -20.5 564.8 5.7 5.3 4.9 4.6 4.3 4.1 3.9 3.7 3.5 3.3 18000 -22.6 542.3 5.5 5.1 4.8 4.5 4.2 3.9 3.7 3.5 3.4 3.2 19000 -24.6 520.6 5.3 4.9 4.6 4.3 4.1 3.8 3.6 3.4 3.3 3.1 20000 -26.6 499.5 5.1 4.8 4.5 4.2 3.9 3.7 3.5 3.3 3.1 3.0 21000 -28.7 479.0 5.0 4.6 4.3 4.0 3.8 3.6 3.4 3.2 3.0 2.9 22000 -30.8 459.2 4.8 4.5 4.2 3.9 3.7 3.5 3.3 3.1 2.9 2.8 23000 -32.9 440.1 4.6 4.3 4.0 3.8 3.5 3.3 3.2 3.0 2.8 2.7 24000 -35.0 421.5 4.5 4.2 3.9 3.6 3.4 3.2 3.1 2.9 2.7 2.6 25000 -37.2 403.4 4.3 4.0 3.8 3.5 3.3 3.1 2.9 2.8 2.7 2.5 26000 -39.4 385.9 4.2 3.9 3.6 3.4 3.2 3.0 2.8 2.7 2.6 2.4 27000 -41.7 368.9 4.0 3.8 3.5 3.3 3.1 2.9 2.7 2.6 2.5 2.4 28000 -44.0 352.4 3.9 3.6 3.4 3.2 3.0 2.8 2.7 2.5 2.4 2.3 29000 -46.3 336.6 3.8 3.5 3.3 3.1 2.9 2.7 2.6 2.4 2.3 2.2 30000 -48.4 321.5 3.6 3.4 3.1 2.9 2.8 2.6 2.5 2.3 2.2 2.1 31000 -50.3 307.3 3.5 3.3 3.0 2.8 2.7 2.5 2.4 2.3 2.1 2.0 32000 -51.9 294.1 3.4 3.1 2.9 2.7 2.6 2.4 2.3 2.2 2.1 2.0 33000 -53.2 281.9 3.3 3.0 2.8 2.6 2.5 2.3 2.2 2.1 2.0 1.9 34000 -54.2 270.7 3.1 2.9 2.7 2.5 2.4 2.3 2.1 2.0 1.9 1.8 35000 -54.8 260.1 3.0 2.8 2.6 2.5 2.3 2.2 2.1 1.9 1.9 1.8 36000 -55.3 249.8 2.9 2.7 2.5 2.4 2.2 2.1 2.0 1.9 1.8 1.7 37000 -55.5 239.2 2.8 2.6 2.4 2.3 2.1 2.0 1.9 1.8 1.7 1.6 38000 -55.7 227.9 2.7 2.5 2.3 2.2 2.0 1.9 1.8 1.7 1.6 1.6 39000 -55.9 215.5 2.5 2.3 2.2 2.0 1.9 1.8 1.7 1.6 1.5 1.5 40000 -56.1 206.2 2.4 2.2 2.1 2.0 1.8 1.7 1.6 1.6 1.5 1.4 41000 -56.2 199.0 2.3 2.2 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.4 42000 -56.4 191.4 2.2 2.1 1.9 1.8 1.7 1.6 1.5 1.4 1.4 1.3 43000 -56.6 183.7 2.2 2.0 1.9 1.7 1.6 1.5 1.5 1.4 1.3 1.3 44000 -56.7 175.7 2.1 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.3 1.2 45000 -56.9 167.7 2.0 1.8 1.7 1.6 1.5 1.4 1.3 1.3 1.2 1.1 46000 -57.1 159.6 1.9 1.7 1.6 1.5 1.4 1.3 1.3 1.2 1.1 1.1 47000 -57.3 151.6 1.8 1.7 1.5 1.4 1.4 1.3 1.2 1.1 1.1 1.0 48000 -57.5 143.7 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.1 1.0 1.0 49000 -57.6 136.0 1.6 1.5 1.4 1.3 1.2 1.2 1.1 1.0 1.0 0.9 50000 -57.8 128.6 1.5 1.4 1.3 1.2 1.2 1.1 1.0 1.0 0.9 0.9