8000 Add Jy/str as a possible unit in FITS output · Issue #61 · lime-rt/lime · GitHub
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Add Jy/str as a possible unit in FITS output #61

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allegroLeiden opened this issue Jul 16, 2015 · 6 comments
Open

Add Jy/str as a possible unit in FITS output #61

allegroLeiden opened this issue Jul 16, 2015 · 6 comments
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@allegroLeiden
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LIME calculates output flux densities in Jy/pixel. The CASA spectrum extractor (CASA 4.3.1) does not recognize this as a proper unit. Maybe we should convert to Jy/arcsec^2, which is recognized?
@smaret
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smaret commented Jul 16, 2015

Does it recognize Kelvins?

@smaret
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smaret commented Jul 17, 2015

I'm not in favor of converting the Jy/pixel to Jy/str. This may confuse users that expect to get Jy/pixel if the img[i]->unit parameter is set to 1 (as in previous LIME versions). What could be done is to add an additional unit code (5?) for Jy/str.

@imckstewart
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No it doesn't like Kelvin, it wants a beam width to be defined for that.

@imckstewart
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I agree about adding extra unit codes rather than redefining old ones.

@smaret
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smaret commented Jul 17, 2015

No it doesn't like Kelvin, it wants a beam width to be defined for that.

Weird. Kelvins units are homogeneous to Jy/str. They do not depend on the beam width -- unless you're talking about antenna or mean beam temperature rather than brightness temperature.

I agree about adding extra unit codes rather than redefining old ones.

OK, I'm labelling this as "enhancement' then.

@smaret smaret changed the title Bad flux unit in FITS output? Add Jy/str as a possible unit in FITS output Jul 17, 2015
@tlunttil
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tlunttil commented Feb 10, 2017 •
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I'm continuing my crusade against dangling issues... There's already unit W m^-2 Hz^-1 sr^-1, which is just Jy/sr times 10^-26. Is there any need for separate unit with Janskies? Or maybe change unit==2 from SI to Janskies? Astronomers using SI units are a rare breed. That would break backward compatibility, though.

Additionally, Janskies (or something else) per square arcsec could be a useful unit.

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@smaret @imckstewart @allegroLeiden @tlunttil
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