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Functions for conversion between flux and magnitude values.
Functions are provided for conversion between flux in Janskys and
AB magnitudes.
A set of constants are also defined for approximate conversions
between the AB and Johnson magnitude scales;
the source for these values is
http://www.astro.utoronto.ca/~patton/astro/mags.html
(citing Frei and Gunn 1995).
-
JOHNSON_AB_V
- Approximate offset between Johnson and AB magnitudes in V band.
VJ~=VAB+
JOHNSON_AB_V
.
-
JOHNSON_AB_B
- Approximate offset between Johnson and AB magnitudes in B band.
BJ~=BAB+
JOHNSON_AB_B
.
-
JOHNSON_AB_Bj
- Approximate offset between Johnson and AB magnitudes in Bj band.
BjJ~=BjAB+
JOHNSON_AB_Bj
.
-
JOHNSON_AB_R
- Approximate offset between Johnson and AB magnitudes in R band.
RJ~=RAB+
JOHNSON_AB_R
.
-
JOHNSON_AB_I
- Approximate offset between Johnson and AB magnitudes in I band.
IJ~=IAB+
JOHNSON_AB_I
.
-
JOHNSON_AB_g
- Approximate offset between Johnson and AB magnitudes in g band.
gJ~=gAB+
JOHNSON_AB_g
.
-
JOHNSON_AB_r
- Approximate offset between Johnson and AB magnitudes in r band.
rJ~=rAB+
JOHNSON_AB_r
.
-
JOHNSON_AB_i
- Approximate offset between Johnson and AB magnitudes in i band.
iJ~=iAB+
JOHNSON_AB_i
.
-
JOHNSON_AB_Rc
- Approximate offset between Johnson and AB magnitudes in Rc band.
RcJ~=RcAB+
JOHNSON_AB_Rc
.
-
JOHNSON_AB_Ic
- Approximate offset between Johnson and AB magnitudes in Ic band.
IcJ~=IcAB+
JOHNSON_AB_Ic
.
-
JOHNSON_AB_uPrime
- Offset between Johnson and AB magnitudes in u' band (zero).
u'J=u'AB+
JOHNSON_AB_uPrime
=u'AB.
-
JOHNSON_AB_gPrime
- Offset between Johnson and AB magnitudes in g' band (zero).
g'J=g'AB+
JOHNSON_AB_gPrime
=g'AB.
-
JOHNSON_AB_rPrime
- Offset between Johnson and AB magnitudes in r' band (zero).
r'J=r'AB+
JOHNSON_AB_rPrime
=r'AB.
-
JOHNSON_AB_iPrime
- Offset between Johnson and AB magnitudes in i' band (zero).
i'J=i'AB+
JOHNSON_AB_iPrime
=i'AB.
-
JOHNSON_AB_zPrime
- Offset between Johnson and AB magnitudes in z' band (zero).
z'J=z'AB+
JOHNSON_AB_zPrime
=z'AB.
-
abToJansky( magAB )
- Converts AB magnitude to flux in Jansky.
F/Jy=10(23-(AB+48.6)/2.5)
-
janskyToAb( fluxJansky )
- Converts flux in Jansky to AB magnitude.
AB=2.5*(23-log10(F/Jy))-48.6
Next Previous Up Contents
Next: Coords
Up: General Functions
Previous: Formats
TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note
253
TOPCAT web page:
http://www.starlink.ac.uk/topcat/
Author email:
m.b.taylor@bristol.ac.uk