Relative Intensity in Spectra: What Does It Mean?

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SUMMARY

Relative intensity in spectra refers to the intensity of light detected within a specific wavelength band as measured by a particular spectrograph. This measurement varies based on the instrument's sensitivity, such as CCD efficiency, and the observational conditions, including whether the observation occurs during twilight or nighttime. It is distinct from specific intensity, which is defined as intensity per unit frequency or wavelength. Understanding these differences is crucial for accurate spectral analysis.

PREREQUISITES
  • Understanding of spectrographs and their designs
  • Knowledge of CCD efficiency and its impact on measurements
  • Familiarity with observational conditions in spectroscopy
  • Concept of specific intensity in light measurement
NEXT STEPS
  • Research the differences between relative intensity and specific intensity in spectroscopy
  • Explore various types of spectrographs and their sensitivity characteristics
  • Learn about the impact of observational conditions on spectral data quality
  • Investigate the principles of integral field units in spectroscopic measurements
USEFUL FOR

Researchers in spectroscopy, optical engineers, and anyone involved in the analysis of spectral data will benefit from this discussion.

Lorna
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Hi everyone,

What does the "relative intensity" mean when we talk about spectra? The intensity relative to what, the background?

Thank you
 
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Different designs of spectrograph will record different intensities for the same wavelength band for the same source - this is due to the sensitivities of each instrument (through CCD efficiency etc..) and also the quality of observation time (spectroscopic, twilight, night etc..) unless you're using an integral field unit, in which case all the light is detected anyway..

Regardless, relative intensity is just a term used to describe the intensity of light detected in a given wavelength band for that specific instrument.
 
so is it the same as the specific intensitiy? the Intensity per unit frequency or wavelength?
 

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