<p>I have light spectral data from astronomy data bases in flux density (flux/Angstrom or flux/Hz) and would like to calculate the flux. How can I calculate the flux from the flux density?</p>

CC BY-SA 4.0
2021-06-08T18:11:10.027Z
Hi Jim, do you know what the difference is between the two. I mean, what they describe, physically? Also, since the answer involves a filter, or some other way to limit a wavelength interval, can you provide a little more information (preferably also including how you've tried to find the answer yourself)?
pela
CC BY-SA 4.0
2021-06-10T11:03:38.330Z
The flux is simply the flux density integrated over some range of wavelengths or frequencies. (Basic dimensional analysis would indicate that, for example, flux = (flux/Angstrom) $\times# Angstrom.)
Peter Erwin
CC BY-SA 4.0
2021-06-12T14:10:02.190Z
I have done a lot of reading and internet searching including books devoted to astronomical spectroscopy such as Planet, Stars and Stellar Systems Vol 2, as well as the help desk of the NED/caltech website. What I really need is the ability to calculate from the spectra the flux at particular wavelengths. For example, the spectrum of 3C 273 has the following values at 1153.32 A the Intensity is 6.4776e-13 [erg/cm^2/s/A]. Is the flux this value multiplied by 452.24 A which is the range over which the spectra is recorded?
Jim Turner
<light><spectra><flux>
Astronomical data bases express spectra in flux density, e.g. ergs/s/cm2/Angstrom( or Hz) how can I calculate the flux, i.e. ergs/s/cm2?
Jim Turner
# Astronomical data bases express spectra in flux density, e.g. ergs/s/cm2/Angstrom( or Hz) how can I calculate the flux, i.e. ergs/s/cm2?

(Asked by: username_0 on 2021-06-08)

I have light spectral data from astronomy data bases in flux density (flux/Angstrom or flux/Hz) and would like to calculate the flux. How can I calculate the flux from the flux density?

**Tags:** light, spectra, flux

> **Comments:**
> **username_1**: Hi Jim, do you know what the difference is between the two. I mean, what they describe, physically? Also, since the answer involves a filter, or some other way to limit a wavelength interval, can you provide a little more information (preferably also including how you've tried to find the answer yourself)?  
> **username_2**: The flux is simply the flux density integrated over some range of wavelengths or frequencies. (Basic dimensional analysis would indicate that, for example, flux = (flux/Angstrom) $\times# Angstrom.)  
> **username_0**: I have done a lot of reading and internet searching including books devoted to astronomical spectroscopy such as Planet, Stars and Stellar Systems Vol 2, as well as the help desk of the NED/caltech website. What I really need is the ability to calculate from the spectra the flux at particular wavelengths. For example, the spectrum of 3C 273 has the following values at 1153.32 A the Intensity is 6.4776e-13 [erg/cm^2/s/A]. Is the flux this value multiplied by 452.24 A which is the range over which the spectra is recorded?  

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## 0 answers

