<p>I am trying to calculate the Equivalent Width of emission lines of a spectrum whose continuum is at 0, making the calculation of the EW impossible.</p>

<p>I have the spectrum of a transient in a galaxy, so I am subtracting the galactic spectrum to study the emission lines, but, by doing so, the continuum level of the resulting spectrum is at 0. I am fitting the lines with multiple gaussians and calculating the EW as flux/continuum, but being the continuum around 0 the EW values become gigantic.</p>

CC BY-SA 4.0
2019-11-28T20:37:26.697Z
Don't subtract the continuum !
ProfRob
CC BY-SA 4.0
2019-11-29T09:17:23.473Z
I have to subtract the continuum to have the "pure" transient spectrum, rather than transient+galaxy
Polemarco
CC BY-SA 4.0
2019-11-29T10:31:49.570Z
Well then if there really is no continuum then equivalent width is meaningless.
ProfRob
<data-analysis><spectroscopy><spectra>
How to calculate Equivalent Width of a spectrum with continuum at 0
Polemarco
# How to calculate Equivalent Width of a spectrum with continuum at 0

(Asked by: username_0 on 2019-11-28)

I am trying to calculate the Equivalent Width of emission lines of a spectrum whose continuum is at 0, making the calculation of the EW impossible.

I have the spectrum of a transient in a galaxy, so I am subtracting the galactic spectrum to study the emission lines, but, by doing so, the continuum level of the resulting spectrum is at 0. I am fitting the lines with multiple gaussians and calculating the EW as flux/continuum, but being the continuum around 0 the EW values become gigantic.

**Tags:** data-analysis, spectroscopy, spectra
> **Comments:**
> **username_1**: Don't subtract the continuum !  
> **username_0**: I have to subtract the continuum to have the "pure" transient spectrum, rather than transient+galaxy  
> **username_1**: Well then if there really is no continuum then equivalent width is meaningless.  

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## 0 answers

