UBV photometric system
Sistema fotométrico UBV
- Date
- 1953 · confidence medium
- Place
- McDonald Observatory, Texas, United States
- Credited to
- Harold Johnson and William Wilson Morgan
- Field
- Cosmos & Earth
What it is
The first standardized photometric system for classifying stars by color, using ultraviolet, blue and visual optical filters; its B−V and U−B color indices are still used in astronomy.
Also called the Johnson or Johnson–Morgan system; a key limitation is that the short-wavelength cutoff of the U filter is set by Earth's atmosphere.
What it led to
- Standardization of stellar classification by color
- Later, broader photometric systems