Difference between revisions of "Central wavelengths and zero points"
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r* = g* - (g* - r*) | r* = g* - (g* - r*) | ||
i* = (Imag - 0.44 +0.16r* )/1.16 | i* = (Imag - 0.44 +0.16r* )/1.16 | ||
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| + | See also http://adsabs.harvard.edu/abs/2014arXiv1412.1474M "Revised Filter Profiles and Zero Points for Broadband Photometry" Mann and von Braun, 2015, PASP, 127, 102 for lots of discussion including revised wavelengths and zero points, even more than are listed here. | ||
Revision as of 17:05, 17 February 2015
Here is a large collection of central wavelengths and zero points, useful for converting between flux densities and magnitudes, which then enables adding points into an SED, or making a color-mag diagram (depending on whether you are starting from mags or flux densities).
band wavelength (um) zero point (Jy) J 1.235 1594 H 1.662 1024 Ks 2.159 666.7 Kshort not Johnson K! http://www.ipac.caltech.edu/2mass/releases/allsky/doc/sec6_4a.html
(note that http://irsa.ipac.caltech.edu/Missions/2mass.html has/had 2.17 um, which isn't right)
I1 3.6 280.9 http://irsa.ipac.caltech.edu/Missions/spitzer.html 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 http://irsa.ipac.caltech.edu/Missions/wise.html 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 Rc 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 see below !! 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
ukidss Z 0.8817 2232 ? Hewett 2006, MNRAS, 367, 454 ukidss Y 1.0305 2026 ? ukidss J 1.2483 1530 ? ukidss H 1.6313 1019 ? ukidss K 2.2010 631 ?
iphas rprime 0.624 3173.3 iphas ha 0.656 2974.4 iphas iprime 0.774 2515.7
denis i 0.778 2499 Fouque et al. 2000, A&AS, 141, 313 denis J 1.221 1595 denis Ks 2.144 665
akari band 1 9 !! Akari reports things already in flux densities. akari band 2 18 Generally, don't trust any other Akari bands, unless you are sure the source is really there.
IRAS band 1 12 28.3 http://irsa.ipac.caltech.edu/IRASdocs/exp.sup/ch6/C2a.html IRAS band 2 25 6.73 IRAS band 3 60 1.19 IRAS band 4 100 0.43
MSX Band A 7.76 http://irsa.ipac.caltech.edu/data/MSX/docs/MSX_psc_es.pdf for 10,000K BB MSX Band B1 4.29 !! MSX should already be in flux density MSX Band B2 4.35 MSX Band C 11.99 MSX Band D 14.55 MSX Band E 20.68
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.
More on filters and bandpasses
For advanced folks (and, frankly, my own future reference): If you have measurements from one of the USNO plate scans of the POSS plates... Monet et al. 2003, AJ, 125, 984 reports these transformations from SDSS EDR photometry [Section 8. eqn 2b-2e].
"B" magnitudes: O = g* + 0.08 + 0.452(g* -r*), sigma = 0.34 J = g* + 0.06 + 0.079(g* - r*), sigma = 0.33 "R" magnitudes: E = r* - 0.20 - 0.086(g* - r*), sigma = 0.30 F = r* - 0.09 - 0.109(g* - r*), sigma = 0.26 "I" magnitudes: N = i* - 0.44 -0.164(r* -i*), sigma =0.31
Thanks to Peregrine McGehee for the following inversion of these formulae:
g* - r * = ([Bmag - Rmag] +0.22)/1.37 g* = Bmag - 0.07 - 0.27(g* - r*) r* = g* - (g* - r*) i* = (Imag - 0.44 +0.16r* )/1.16
See also http://adsabs.harvard.edu/abs/2014arXiv1412.1474M "Revised Filter Profiles and Zero Points for Broadband Photometry" Mann and von Braun, 2015, PASP, 127, 102 for lots of discussion including revised wavelengths and zero points, even more than are listed here.
