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mfouesneau / pyphot

suite to deal with passband photometry
https://mfouesneau.github.io/pyphot/
MIT License
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SDSS filters: incorrect treatment #14

Closed joannawooastro closed 5 years ago

joannawooastro commented 5 years ago

I noticed that the SDSS filters are treated as photon counters, but according to the Filter Profile Service, they are energy counters (eg, http://svo2.cab.inta-csic.es/svo/theory/fps3/index.php?id=SLOAN/SDSS.g). Therefore, the pivot wavelengths and fluxes from get_flux are incorrect by a small amount.

mfouesneau commented 5 years ago

As far as I know, there is no more energy detector in the optical, so that's new to me. Of course, that changes things, I'll have a look. This could be a transmission curve definition. You can change them manually when using them with set_type until I clarify the situation.

mfouesneau commented 5 years ago

As far as I can dig, I am using the correct definition of SDSS transmissions. Based on the SDSS page: http://classic.sdss.org/dr7/instruments/imager/, you can see that I get the right mean wavelength values. As far as I can tell, I believe this is a mistake on the SVO side, but I'll double check with SDSS gurus.

mfouesneau commented 5 years ago

According to SDSS people I talked to, its curves are defined in counts, not energy. Closing this issue.