Introduction
The Spanish Virtual Observatory (SVO) Filter Profile Service is a great resource for homogenized photometric filter curves and metadata. With svo_filters, I tried to create a lightweight and flexible package to incorporate these filters into Python applications.
Install via PyPI with
pip install svo_filtersOr install via Github with
git clone https://github.com/hover2pi/svo_filters.git
python svo_filters/setup.py installThen import like so
from svo_filters import svoThe actual filters are stored locally as XML files and can be viewed with
svo.filters() Band CalibrationReference FWHM Facility FilterProfileService ... wl_max wl_min Instrument
str91 str86 float64 str91 str91 ... float64 float64 str91
----------------- -------------------------------------------------------------------------------------- ------- ---------- -------------------- ... -------- -------- ----------
2MASS.H http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003AJ....126.1090C&db_key=AST 0.26096 2MASS ivo://svo/fps ... 1.8231 1.47874 --
2MASS.J http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003AJ....126.1090C 0.21491 2MASS ivo://svo/fps ... 1.4068 1.08065 --
2MASS.Ks http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003AJ....126.1090C 0.27846 2MASS ivo://svo/fps ... 2.35524 1.95437 --
ACS_HRC.F435W -- 0.08852 HST ivo://svo/fps ... 0.48613 0.3599 ACS
ACS_HRC.F555W -- 0.123 HST ivo://svo/fps ... 0.62049 0.45867 ACS
ACS_HRC.F658N -- 0.0072 HST ivo://svo/fps ... 0.66594 0.65099 ACS
ACS_HRC.F775W -- 0.15151 HST ivo://svo/fps ... 0.86307 0.68014 ACS
ACS_HRC.F850LP -- 0.15317 HST ivo://svo/fps ... 1.09465 0.80151 ACS
Cousins.I -- 0.10937 -- ivo://svo/fps ... 0.90006 0.70665 --
Cousins.R -- 0.15165 -- ivo://svo/fps ... 0.795 0.55 --
FourStar.J -- 0.22829 LCO ivo://svo/fps ... 1.37261 1.10964 FourStar
FourStar.J1 -- 0.09882 LCO ivo://svo/fps ... 1.12095 0.9908 FourStar
FourStar.J2 -- 0.13685 LCO ivo://svo/fps ... 1.23809 1.06006 FourStar
FourStar.J3 -- 0.13998 LCO ivo://svo/fps ... 1.37794 1.20031 FourStar
Gaia.bp -- 0.24832 GAIA ivo://svo/fps ... 0.67089 0.32793 GAIA
Gaia.G -- 0.45783 GAIA ivo://svo/fps ... 1.08275 0.33212 GAIA
Gaia.rp -- 0.31164 GAIA ivo://svo/fps ... 1.06083 0.61768 GAIA
GALEX.FUV -- 0.02278 GALEX ivo://svo/fps ... 0.18064 0.13403 --
GALEX.NUV -- 0.07956 GALEX ivo://svo/fps ... 0.30067 0.16925 --
IRAC.I1 -- 0.74317 Spitzer ivo://svo/fps ... 3.96144 3.12962 IRAC
IRAC.I2 -- 1.00968 Spitzer ivo://svo/fps ... 5.05606 3.91733 IRAC
... ... ... ... ... ... ... ... ...
PS1.r -- 0.14044 PAN-STARRS ivo://svo/fps ... 0.70357 0.53862 PAN-STARRS
PS1.y -- 0.06282 PAN-STARRS ivo://svo/fps ... 1.08385 0.91005 PAN-STARRS
PS1.z -- 0.10343 PAN-STARRS ivo://svo/fps ... 0.9346 0.8028 PAN-STARRS
SDSS.g www.sdss.org/DR2/algorithms/fluxcal.html 0.12627 SLOAN ivo://svo/fps ... 0.55493 0.37825 --
SDSS.i www.sdss.org/DR2/algorithms/fluxcal.html 0.12389 SLOAN ivo://svo/fps ... 0.83895 0.66895 --
SDSS.r www.sdss.org/DR2/algorithms/fluxcal.html 0.11495 SLOAN ivo://svo/fps ... 0.69891 0.54153 --
SDSS.u www.sdss.org/DR2/algorithms/fluxcal.html 0.05823 SLOAN ivo://svo/fps ... 0.40282 0.30483 --
SDSS.z www.sdss.org/DR2/algorithms/fluxcal.html 0.09944 SLOAN ivo://svo/fps ... 1.08333 0.79604 --
WFC3_IR.F125W -- 0.30052 HST ivo://svo/fps ... 1.41392 1.08446 WFC3
WFC3_IR.G102 -- 0.57288 HST ivo://svo/fps ... 1.77466 1.04039 WFC3
WFC3_IR.G141 -- 0.57288 HST ivo://svo/fps ... 1.77466 1.04039 WFC3
WFC3_UVIS2.F814W -- 0.15047 HST ivo://svo/fps ... 0.96836 0.69782 WFC3
WFC3_UVIS2.F850LP -- 0.1168 HST ivo://svo/fps ... 1.09224 0.82505 WFC3
WFPC2.F336W -- 0.04909 HST ivo://svo/fps ... 0.37903 0.29565 WFPC2
WFPC2.F439W -- 0.07058 HST ivo://svo/fps ... 0.47581 0.38935 WFPC2
WFPC2.F656N -- 0.00285 HST ivo://svo/fps ... 0.65874 0.65384 WFPC2
WFPC2.F814W -- 0.25562 HST ivo://svo/fps ... 1.00426 0.69476 WFPC2
Wircam.Y -- 0.11053 CFHT ivo://svo/fps ... 1.1134 0.9386 Wircam
WISE.W1 http://wise2.ipac.caltech.edu/docs/release/prelim/expsup/figures/sec4_3gt4.gif 0.63579 WISE ivo://svo/fps ... 3.87239 2.7541 --
WISE.W2 http://wise2.ipac.caltech.edu/docs/release/prelim/expsup/figures/sec4_3gt4.gif 1.10732 WISE ivo://svo/fps ... 5.34136 3.96333 --
WISE.W3 http://wise2.ipac.caltech.edu/docs/release/prelim/expsup/figures/sec4_3gt4.gif 6.2758 WISE ivo://svo/fps ... 17.26134 7.44304 --
WISE.W4 http://wise2.ipac.caltech.edu/docs/release/prelim/expsup/figures/sec4_3gt4.gif 4.73973 WISE ivo://svo/fps ... 27.91072 19.52008 --Load a Photometric Filter
To load a filter object, just pass the band name to the Filter class. We can then view the metadata and see a plot!
H_band = svo.Filter('2MASS.H')
H_band.info()
H_band.plot() Attributes Values
-------------------- --------------------------------------------------------------------------------------
Band H
CalibrationReference http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003AJ....126.1090C&db_key=AST
FWHM 0.26096
Facility 2MASS
FilterProfileService ivo://svo/fps
MagSys Vega
PhotCalID 2MASS/2MASS.H/Vega
PhotSystem 2MASS
ProfileReference http://www.ipac.caltech.edu/2mass/releases/allsky/doc/sec6_4a.html
WavelengthCen 1.64872
WavelengthEff 1.662
WavelengthMax 1.8231
WavelengthMean 1.662
WavelengthMin 1.47874
WavelengthPeak 1.671
WavelengthPhot 1.64238
WavelengthPivot 1.64949
WavelengthUCD em.wl
WavelengthUnit um
WidthEff 0.25094
ZeroPoint 1.1113698753332439e-10
ZeroPointType Pogson
ZeroPointUnit erg / (Angstrom cm2 s)
filterID 2MASS/2MASS.H
n_bins 1
path /Users/jfilippazzo/Documents/Modules/svo_filters/svo_filters/data/filters/2MASS.H
pixels_per_bin 58
refs ['AST']
wl_max 1.8231
wl_min 1.47874 
The actual relative spectral response curve is stored as an array of the wavelength and throughput.
H_band.rsr.shape(2, 58)Load a Grism
Filters can also be binned arbitrarily, for use with grisms. We can pass integers to the n_bins or pixels_per_bin arguments to specify the number of wavelength bins or pixels per bin, respectively.
G141 = svo.Filter('WFC3_IR.G141', n_bins=15)
G141.info()
G141.plot() Attributes Values
-------------------- --------------------------------------------------------------------------------------
FWHM 0.57288
Facility HST
FilterProfileService ivo://svo/fps
Instrument WFC3
MagSys Vega
PhotCalID HST/WFC3_IR.G141/Vega
PhotSystem WFC3
ProfileReference http://www.stsci.edu/hst/wfc3/documents/handbooks/currentIHB/
WavelengthCen 1.38902
WavelengthEff 1.32829
WavelengthMax 1.77466
WavelengthMean 1.39879
WavelengthMin 1.04039
WavelengthPeak 1.48039
WavelengthPhot 1.3481
WavelengthPivot 1.38869
WavelengthUCD em.wl
WavelengthUnit um
WidthEff 0.52172
ZeroPoint 2.2612502006498423e-10
ZeroPointType Pogson
ZeroPointUnit erg / (Angstrom cm2 s)
filterID HST/WFC3_IR.G141
n_bins 15
path /Users/jfilippazzo/Documents/Modules/svo_filters/svo_filters/data/filters/WFC3_IR.G141
pixels_per_bin 580
refs []
wl_max 1.77466
wl_min 1.04039 
Now we can apply our filter to a spectrum like so
# Get the filter object
import numpy as np
G141 = svo.Filter('WFC3_IR.G141', n_bins=15)
# Get a spectrum
file = resource_filename('svo_filters', 'data/spectra/vega.txt')
spec = np.genfromtxt(file)
# Applyt the filter
filtered = G141.apply(spec, plot=True)
Filters are fun!
Licensed
This project is Copyright (c) Joe Filippazzo and licensed under the terms of the BSD 3-Clause license. See the licenses folder for more information.
