We have created a digital spectral library , using low resolution optical spectra , of photometric and spectral standard stars .
The data were acquired using the Cassegrain Spectrograph installed on the 1.9m Radcliffe telescope at the South African Astronomical Observatory .
The library consists of optical wavelength ( \simeq 3500 - 7500Å ) spectra for main sequence and giant stars encompassing those most commonly observed in the Galaxy , namely the late-B , A- , F- , G- , K- , and early- to mid-M stars .
We intend that our standard star spectra will be especially useful for spectral classification of stars in the field and Galactic clusters alike , and will have high pedagogic value when included into representative Introductory Astronomy or Stellar Astronomy curricula for undergraduate astronomy major and minor programs .

We exploit the spectral library in order to derive spectral types for seventy-six optically and X-ray selected members of the young open cluster ngc 6475 .
Comparison of spectral-type , optical and infrared photometric data to theoretical colors derived from spectral type show that the reddening of the cluster is E _ { ( B - V ) } = 0.068 \pm 0.012 ( 1 \sigma =0.058 ) , a vector consistent with earlier surveys .
Our analysis also highlights the utility of such spectra in rejecting cluster non-members , thereby allowing the creation of a clean sample of bona fide cluster members for follow-up science observations .