This tool calculates the atmospheric refraction (and associated parameters)
as a function of wavelength for the La Palma observatory given the declination
and hour angle of the source.
Azimuth: 0.00 degrees (South being zero)
Elevation: 61.25 degrees Zenith distance: 28.75 degrees
Airmass: 1.14
Parallactic angle: 0.00 degrees (North through East)
Atmospheric refraction is calculated based on an approximation given in Meeus, 1991
Differential refraction is calculated based on an approximation given in Filippenko, 1982
Calculations assume an air temperature of 7.0 degrees,
at an air pressure of 755 mbar and a relative water pressure of 3.1 mbar
Approximate atmospheric refraction: 24.80 arcsec
Differential refraction:
| Wavelength | Refractive Index | Differential refraction |
| (nm) | (n - 1) 10^6 | (arcsec to 500 nm) |
| 300 | 223.19 | 1.09 |
| 350 | 219.02 | 0.62 |
| 400 | 216.44 | 0.33 |
| 450 | 214.73 | 0.14 |
| 500 | 213.53 | 0.00 |
| 550 | 212.66 | -0.10 |
| 600 | 212.01 | -0.17 |
| 650 | 211.50 | -0.23 |
| 700 | 211.10 | -0.28 |
| 750 | 210.78 | -0.31 |
| 800 | 210.52 | -0.34 |
| 850 | 210.30 | -0.37 |
| 900 | 210.12 | -0.39 |
| 950 | 209.97 | -0.40 |
| 1000 | 209.84 | -0.42 |
| 1500 | 209.18 | -0.49 |
| 2000 | 208.95 | -0.52 |
| 2500 | 208.84 | -0.53 |
| 3000 | 208.78 | -0.54 |
| 5000 | 208.70 | -0.55 |
| 10000 | 208.67 | -0.55 |
| 20000 | 208.66 | -0.55 |
Sources:
Jean Meeus, 1991, Astronomical Algorithms, Willmann-Bell, Inc.
Alexei Filippenko, 1982, PASP 94, 715