The Balmer Series is a set of Hydrogen Spectral Lines emitted when the electron orbit descends from n greater than 2 to n = 2. The series is named for Johann Balmer. (As opposed to the Lyman Series, from n greater than 1 to n = 1.)
Wavelength = Balmer's Constant × ( m² / ( m²-n² )
Balmer's Constant = 3.6450682 × 10-7 m or 364.50682 nm (same as 4/RH, the Rydberg Constant for Hydrogen).
Balmer-Break Galaxy (BBG)
Emission Line Galaxy (ELG)
HII Region (HII)
Star Formation Rate (SFR)