**2. Early Work—The Magellanic Clouds**

The early objective prism surveys by the Harvard College Observatory and the resulting Henry Draper Catalog and Extension (HD and HDE) provided the first survey with spectral types of the brightest stars in the Magellanic Clouds [3,4]. The HDE however did not cover the Small Cloud. Feast, Thackeray & Wesselink [5] published the first detailed list of the brightest stars in the Magellanic Clouds with spectral classifications based on slit spectra of individual stars. Their paper included magnitudes, colors, positions, radial velocities and notes on the individual stars relative to emission lines and other features for 50 stars in the SMC and 105 in the LMC. The HDE catalog was the primary source for the LMC stars, plus stars selected as blue based on their colors in the 30 Dor region. The SMC list relied on "B" type stars from the HD plus emission line stars from the survey by Henize [6]. Their work did not include the red or M-type supergiants. The reddest stars in their study were the very luminous F- and G-type supergiants. Their HR Diagram, reproduced here in Figure 1, while not complete, shows the visually brightest stars with M*v* approaching −10 mag.

**Figure 1.** The HR Diagram for the brightest stars in the LMC and SMC from [5]. LMC stars are closed symbols and those in the SMC are shown as open symbols.

Additional work on the fainter stellar populations of hot or OB-type stars and red M-type stars was provided by the lower resolution objective prism surveys throughout the 1960s and 1970s. These included surveys for OB type stars in the LMC and SMC by Sanduleak [7,8] and Fehrenbach & Duflot [9] and for the M-type stars by Westerlund [10,11] and Blanco et al. [12,13]. These necessary photographic surveys provided extensive finding lists for further spectral classification leading to the first comprehensive HR Diagrams for these two galaxies and the comparison of their massive and luminous stellar populations with the Milky Way.
