What are the flux units for des_dr1?

Question

I can't find the units for the columns auto_flux_BAND or really any of the flux columns in the table.

Answer 1

Thanks for your question.

From https://sextractor.readthedocs.io/en/des_dr1/Photom.html#automatic-aperture-flux via https://des.ncsa.illinois.edu/releases/dr1/dr1-products/dr1-schema they are ADUs or Pogson units.

Comments

Thank you for you quick response. Is there a conversion to get ADUs into an actual flux unit? Without the gain or exposure time I am not sure what to do with a flux in ADUs.

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Hi there, so Adam is right that the units of the flux columns are ADUs (we should add that to the column descriptions), i.e. they are counts; to convert to electrons you can use the DECam gain, ~4 e-/ADU.  But the magnitudes are on the AB system, so to get linear physical flux from the magnitudes you can convert through the AB mag definition, e.g.: https://en.wikipedia.org/wiki/AB_magnitude.  I think this is probably what you want to use.

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Thanks for getting back to me. I was able to used the magnitudes to get a flux and then used the S/N of the ADU flux and error to get a flux error in flux units.

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Great!  You could also convert mag errors to flux errors through 1.086*sigma_flux/flux = sigma_mag