PyHdust filters
=================
- ESO SkyCalc filters ("Johnson", from *U* to *Q*, uppercase, no instrument ID)
- `filter_instrument` (otherwise)

**Wavelength in Angstroms!**

Zero point levels
===================

=================== ======================================
Band                Photometric zeropoint in ergs/s/cm2/A
                     (flux for zero mag in Vega system)
=================== ======================================
U                   U0 = 4.18023e-09
B                   B0 = 6.60085e-09
V                   V0 = 3.60994e-09
R                   R0 = 2.28665e-09
I                   I0 = 1.22603e-09
Z                   Z0 = 7.76068e-10
Y                   Y0 = 5.973e-10
J                   J0 = 3.12e-10
H                   H0 = 1.14e-10
K                   K0 = 3.94e-11
L                   L0 = 4.83e-12
M                   M0 = 2.04e-12
N                   N0 = 1.23e-13
Q                   Q0 = 6.8e-15

Paranal_VISIR.J122  Paranal_VISIR.J122_0 = 5.782e-14
=================== ======================================

Sources
==========
SVO Filter Profile Service - filter standardization in the VO
    http://svo2.cab.inta-csic.es/svo/theory/fps3/index.php?mode=browse

SkyCalc - ESO Sky Model Calculator (contains Photometric zeropoint in ergs/s/cm2/A)
    https://www.eso.org/observing/etc/doc/skycalc/helpskycalc.html

Wikipedia - Photometric system article
	https://en.wikipedia.org/wiki/Photometric_system

Other filters lists
	http://www.astro.caltech.edu/~capak/filters/index.html

	http://www.aip.de/en/research/facilities/stella/instruments/data

	http://www.mso.anu.edu.au/~brad/filters.html

AstroSurf - comercial filters response
	http://www.astrosurf.com/buil/filters/curves.htm
