text: This classification was developed from broad band spectra ( between 0.31 Î 1\/4 m and 1.06 Î 1\/4 m ) obtained during the Eight-Color Asteroid Survey ( ECAS ) in the 1980s , in combination with albedo measurements .
simplified: This classification was developed from broad band spectra ( between 0.31 Î 1\/4 m and 1.06 Î 1\/4 m ) obtained during the Eight-Color Asteroid Survey ( ECAS ) in the 1980s , in combination with albedo measurements ( 4 ) .