Hot Star Extension to the Hubble Space Telescope Stellar Spectral
  Library
  Libraries of stellar spectra find many uses in astrophysics, from photometric
calibration to stellar population synthesis. We present low resolution spectra
of 40 stars from 0.2 micrometers (ultraviolet) to 1.0 micrometers (near
infrared) with excellent fluxing. The stars include normal O-type stars,
helium-burning stars, and post-asymptotic giant branch (PAGB) stars. Spectra
were obtained with the Space Telescope Imaging Spectrograph (STIS) installed in
the Hubble Space Telescope (HST) using three low resolution gratings, G230LB,
G430L, and G750L. Cosmic ray hits and fringing in the red were corrected. A
correction for scattered light was applied, significant only for our coolest
stars. Cross-correlation was used to bring the spectra to a common, final, zero
velocity wavelength scale. Finally, synthetic stellar spectra were used to
estimate line of sight dust extinction to each star, and a five-parameter dust
extinction model was fit, or a one-parameter fit in the case of low extinction.
These spectra dovetail with the similar Next Generation Stellar Library (NGSL)
spectra, extending the NGSL's coverage of stellar parameters, and extending to
helium burning stars and stars that do not fuse. The fitted dust extinction
model showed considerable variation from star to star, indicating variations in
dust properties for different lines of sight. Interstellar absorption lines are
present in most stars, notably MgII.
