This data set contains visible-wavelength (0.435-0.925 micron) spectra for 1341
main-belt asteroids observed during the second phase of the Small Main-belt Asteroid
Spectroscopic Survey (SMASSII) between August 1993 and March 1999. The purpose of
the SMASSII survey was to provide a new basis for studying the compositional
diversity and structure of the asteroid belt. Based on experiences gained from the
earlier SMASS survey, SMASSII focused on producing an even larger, internally
consistent set of CCD spectra for small (D < 20 km) main-belt asteroids. The
observing strategies and procedures used during SMASSII roughly parallel those used
in the first survey (Xu et al. Icarus 115 1-35, 1995), though several minor changes
were made in instrumentation and in portions of the data reduction process.

This data set contains 52-color IR data of asteroids, taken using a double circularly variable filter. The short wavelength portion of the CVF covered the octave from 0.8 to 1.6 microns with 3 percent resolution, while the long wavelength portion covered 1.5 to 2.6 microns with 5 percent resolution. Most of the data are unpublished other than in this PDS data set.

This data set is comprised of the VNIR (0.69-2.5 micron) spectra of twenty-five
D-type asteroids from varying Solar System locations. The spectra were obtained from
NASA/IRTF on Mauna Kea between 2016-2019 using the SpeX instrument in Low-Resolution
Prism mode and the 0.8 x 15" slit. Guiding was performed using spillover light from
the slit (GuideDog) for targets with apparent magnitude > 15.5. For targets fainter
than magnitude 15.5, guiding was accomplished using the MORIS CCD imager.