Difference between revisions of "Central wavelengths and zero points"

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   sloan z    9060*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, 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.
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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 (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.