Useful Astronomical Data
This page contains a collection of reference data for astronomical photometry, including flux zeropoints and magnitude conversions.
Vega Flux Zeropoints
Based on the Bessell et al. (1998) Johnson-Cousins-Glass System.
| Quantity | U | B | V | R | I | J | H | K | Notes/Units |
|---|---|---|---|---|---|---|---|---|---|
| \( \lambda_{eff} \) | 0.36 | 0.438 | 0.545 | 0.641 | 0.798 | 1.22 | 1.63 | 2.19 | microns |
| \( \Delta\lambda \) | 0.06 | 0.09 | 0.085 | 0.15 | 0.15 | 0.26 | 0.29 | 0.41 | microns |
| \( f_{\nu} \) | 1.79 | 4.063 | 3.636 | 3.064 | 2.416 | 1.589 | 1.021 | 0.64 | \( 10^{-20} \) erg cm\(^{-2}\) s\(^{-1}\) Hz\(^{-1}\) |
| \( f_{\lambda} \) | 417.5 | 632 | 363.1 | 217.7 | 112.6 | 31.47 | 11.38 | 3.961 | \( 10^{-11} \) erg cm\(^{-2}\) s\(^{-1}\) Å\(^{-1}\) |
| \( \Phi_{\lambda} \) | 756.1 | 1392.6 | 995.5 | 702.0 | 452.0 | 193.1 | 93.3 | 43.6 | photons cm\(^{-2}\) s\(^{-1}\) Å\(^{-1}\) |
AB Flux Zeropoints
Data for SDSS filters on the AB system (Fukugita et al. 1996).
| Quantity | u | g | r | i | z | Notes/Units |
|---|---|---|---|---|---|---|
| \( \lambda_{eff} \) | 0.356 | 0.483 | 0.626 | 0.767 | 0.910 | microns |
| \( \Delta\lambda \) | 0.0463 | 0.0988 | 0.0955 | 0.1064 | 0.1248 | microns |
| \( f_{\nu} \) | 3631 | 3631 | 3631 | 3.631 | 3631 | Jy |
| \( f_{\lambda} \) | 859.5 | 466.9 | 278.0 | 185.2 | 131.5 | \( 10^{-11} \) erg cm\(^{-2}\) s\(^{-1}\) Å\(^{-1}\) |
| \( \Phi_{\lambda} \) | 1539.3 | 1134.6 | 875.4 | 714.5 | 602.2 | photons cm\(^{-2}\) s\(^{-1}\) Å\(^{-1}\) |
ST Magnitudes
The ST magnitude system is defined such that an object with constant flux \( F_{\lambda} = 3.63 \times 10^{-9} \) erg cm\(^{-2}\) s\(^{-1}\) Å\(^{-1}\) will have \( ST = 0 \) in every filter.
General formula: \[ ST_{mag} = -2.5 \log F_{\lambda} - 21.1 \]