How to read it
Frequency is in gigahertz. Intensity has been normalized so the largest supplied value equals 1; it has no physical intensity unit. The curve only supports comparing the shape of these ten points.
Data Lab
CMB Spectrum Lab
What can a normalized curve show about spectral shape, and what requires the calibrated COBE/FIRAS record?
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CSV schema
frequency_ghz is frequency in GHz and normalized_intensity is a dimensionless editorial value. The plotted line reads those exact pairs and smooths visually between them.
Limits
These are not COBE/FIRAS measurements, residuals or a fitted blackbody. They contain no uncertainty or calibration information and cannot establish the CMB temperature or precision of the fit. Use the linked mission record for those claims.
Try it yourself
Lab task
Identify the peak of the normalized teaching curve. Then list the calibrated intensity units, uncertainties and model residuals you would need before evaluating a blackbody fit.
Signal interpretation console · data labs
CMB Spectrum / observation pipeline
Photons
Identify wavelength, exposure, field of view and observing date before reading the image.
Detector
Separate object signal from point-spread function, noise, saturation and selection.
Calibration
Track background removal, alignment, scaling and color mapping as part of the measurement.
Physical claim
Connect “The Cosmic Microwave Background” to “Scientific Significance” through an explicit model.
PRIMARY READOUT
Explore the cosmic microwave background radiation spectrum—the oldest light in the universe, dating back to 380,000 years after the Big Bang.
MODEL WARNING
A transit spectrum is a small wavelength-dependent change in combined light; stellar activity, clouds and instrument systematics can mimic atmospheric features. Projection, distance, extinction or adopted parameters may offer another explanation.
CROSS-CHECK
Query NASA LAMBDA: COBE/FIRAS Overview and seek an independent wavelength, spectrum, motion or catalogue measurement.