SRF.centroid() - Mistake

[oam31]

import numpy as np from typhon.physics.units.common import ureg from typhon.physics.units.em import SRF frequency = ureg.Quantity(np.array( [37011414567901.24, 36560055853658.54, 36119573253012.05, 35689578333333.336, 35269700941176.47, 34859588139534.887, 34458903218390.805, 34067324772727.27, 33684545842696.633, 33310273111111.11, 32944226153846.156]), 'Hz') weight = np.array([1]*11) srf = SRF(frequency, weight) print(srf.centroid())

--> 34906834926126.227 hertz ** 2

Why hertz ^2 and not hertz ?

Thanks

[gerritholl]

Units of weight should be 1/Hz. At least that's what's expected here.

[oam31]

;-) ok but generally, a weight is dimensionless...

[gerritholl]

It depends on how the sensor response is defined. A channel radiance is the spectral radiance integrated over the channel, weighted by the spectral response function. If I remember correctly, here I have used a normalisation such that the integral of the spectral response function is dimensionless. For the integral of the spectral response function with frequency to be dimensionless, the spectral response at any given frequency must be 1/Hz.

Perhaps weight is not the best term here, but I think physically it makes sense that the value of the spectral response function at any given frequency has the dimensions 1/[frequency].

[oam31]

It seems to me that the spectral response of an instrument for a frequency or wavelength is given dimensionless ( e.g. http://www.astro.ucla.edu/~wright/WISE/passbands.html ).

I have tried your solution, but it does not seem to work. I just replaced : weight = np.array([1]*11) by: weight = ureg.Quantity(np.array([1]*11), '1/Hz')

[gerritholl]

Maybe you're right, I don't remember right now. I don't know why the result is wrong; it's been a while since I worked on this, sorry.