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spacetelescope / pysynphot

Synthetic Photometry.
http://pysynphot.readthedocs.io/en/latest/
BSD 3-Clause "New" or "Revised" License
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k(lambda) of pysynphot #150

Closed hahareally closed 1 year ago

hahareally commented 1 year ago

Hi, I am trying to verify the k(lambda) value of pysynphot(https://training-library.readthedocs.io/en/latest/pysynphot.html). Assuming E(B-V)=0.2 and a starburst galaxy, import pysynphot as S extinct = S.Extinction(0.2, 'xgalsb') extinct(6563) 0.76

But according to eq.3 of Calzetti2000 (https://iopscience.iop.org/article/10.1086/308692/pdf), k(6563A)=3.32 Lintrinsic=Lobservation*10**(0.4 x 3.32 x 0.2)=Lobservation x 1.84

0.76>>1/1.84

So which value is correct?

ps: where is the k(lambda) of Cardelli1989 (https://ui.adsabs.harvard.edu/abs/1989ApJ...345..245C/abstract)?

Thank you!

andresgur commented 1 year ago

I get k(Halpha) = 2.37 for Rv=3.1 and 3.77 for Rv=4.5, which gives me ~0.65 and 0.49 for ratio. I don't know what xgalsb refers to, maybe that assumes a certain value for Rv, plus what curve uses psynphot?

pllim commented 1 year ago

Hello, looks like this is more of a question for https://github.com/spacetelescope/ins-training-library/issues . If the authors there determines this to be a software bug, please then submit a minimally reproducible example with the expected result.

Furthermore, PySynphot is deprecated, please use https://stsynphot.readthedocs.io/en/latest/

pllim commented 1 year ago

INS has confirmed that the referenced training page is now defunct. Closing this issue.