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Table 1 Spectral bandwidth and relative scotopic to photopic ratio impacts of the nine lamp types shown in Fig. 4

From: The growing threat of light pollution to ground-based observatories

Lamp type* Spectral bandwidth** (nm) Relative scotopic ratio***
Lamp 1 km 100 km
LPS 1 0.4 0.4 0.5
NBALED**** 34 0.5 0.5 0.6
HPS 62 +  1.0 1.0 1.0
PCALED 152 0.8 0.8 0.9
LED 2400 K 272 1.8 1.8 1.6
LED 3100 K 280 2.3 2.3 2.0
LED 5100 K 250 3.3 3.2 2.8
FLEDww 210 1.5 1.5 1.5
FLEDcw 211 1.9 1.9 1.9
  1. *Characteristics of LEDs, including NBALED, can be expected to vary depending on manufacturer and lot
  2. **Wavelength range where radiance >  = 10% of peak; + indicates discontinuous ranges
  3. ***Relative to HPS with S/P = 0.64
  4. ****Peak wavelength 595 nm