| Atmospheric Extinction | ||||
| λ [Å] | λ [μm] | NσR [km-1] | NσRH = τλ |
Iν(sealevel)
/ Iν0 = e-τ = attenuation at zenith |
| 3600 (U) | 0.36 | 0.0575 | 0.454 | 0.635 |
| 4400 (B) | 0.44 | 0.0257 | 0.203 | 0.816 |
| 5500 (V) | 0.55 | 0.0105 | 0.0833 | 0.920 |
| 7000 (R) | 0.70 | 0.00402 | 0.0318 | 0.969 |
| 10000 | 1.00 | 0.00097 | 0.00762 | 0.9924 |
Note that Iλ
/ Iλ0 = e -τ sec z
and τ = NσλHe-h/H.
sec z = the number of air masses (relative to the zenith) along the line
of sight at zenith angle z.