Difference between revisions of "Central wavelengths and zero points"
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| − | BE CAREFUL to keep track of whether you are working with Vega-based magnitudes or AB mags. Vega magnitudes define things with respect to a Vega spectrum, but some folks (largely extragalactic folks) define things with respect to a flat spectrum source instead, and those are AB mags. Most Sloan folks (even those folks working with stars) work in AB mags instead. For AB mags, you always use a flat reference spectrum, so the zero point is 3631 Jy for all bands. | + | BE CAREFUL to keep track of whether you are working with Vega-based magnitudes or AB mags. Vega magnitudes define things with respect to a Vega spectrum (see [[Units]] page), but some folks (largely extragalactic folks) define things with respect to a flat spectrum source instead, and those are AB mags. Most Sloan folks (even those folks working with stars) work in AB mags instead. For AB mags, you always use a flat reference spectrum, so the zero point is 3631 Jy for all bands. |
Revision as of 15:57, 11 August 2011
Here is a large collection of central wavelengths and zero points, useful for converting between flux densities and magnitudes, and for adding points into an SED.
band wavelength (um) zero point (Jy) J 1.25 1594 H 1.65 1024 K 2.17 666.7
I1 3.6 280.9 I2 4.5 179.7 I3 5.8 115.0 I4 8.0 64.13
M1 24 7.14 M2 70 0.775 M3 160 0.159
W1 3.4 309.54 W2 4.6 171.79 W3 12 31.676 W4 22 8.3635
U 0.36 1755 B 0.44 4000.87 V 0.55 3597.28 R 0.71 3080 !! Cousins R not the same as Johnson R! Ic 0.79 2432.84 !! Cousins I (not the same as Johnson I!)
sloan u 2910*1d-4 !! 2910 A, and there are 10^-4 um per A. (etc for rest) sloan g 4810*1d-4 sloan r 6230*1d-4 sloan i 7640*1d-4 sloan z 9060*1d-4
BE CAREFUL to keep track of whether you are working with Vega-based magnitudes or AB mags. Vega magnitudes define things with respect to a Vega spectrum (see Units page), but some folks (largely extragalactic folks) define things with respect to a flat spectrum source instead, and those are AB mags. Most Sloan folks (even those folks working with stars) work in AB mags instead. For AB mags, you always use a flat reference spectrum, so the zero point is 3631 Jy for all bands.
