Data Set Overview  :  Near-infrared spectral observations of 52 asteroids located at ~2.5 AU were  obtained using the NASA IRTF SpeX instrument covering the 0.7 to 2.5 micron  spectral interval. The reflectance spectra were obtained using the  low-medium resolution spectrograph SpeX (RAYNER et al. 2003). SpeX was used in the low- resolution spectrographic mode (asteroid mode) for two reasons:  1) its ability to obtain spectra with a fairly high signal to noise ratio  (SNR) even for weak signal received from asteroids and 2) its ability to  resolve broad absorption features produced by mafic silicate minerals.   The data in each asteroid spectral file contains three columns: wavelength  (in microns), relative reflectance, and uncertainty in relative reflectance. The label also includes keywords indicating the target name (asteroid name  and number), target type (asteroid), UT start and end dates of the first and last asteroid observations used in creating the final reduced, calibrated  average spectrum, number of exposures used in creating the final reduced,  average calibrated spectrum, net integration time, apparent V-mag, phase  angle, geocentric distance, heliocentric distance of the asteroid at the  time of the respective asteroid observations. The solar analog star used  for each asteroid's spectral calibration is listed. The listed airmass is  the airmass at the start of the first observation of the respective  asteroid.   Observations  :  During an observing run the telescope nodded between the A beam and the B  beam(For SpeX, the telescope nod distance is 7.5 arcsec, positioning the  spectrum image at 1/4 and 3/4 distance along the 15 arcsec slit), so images  were taken in spectral image pairs of the target asteroid, local standard  star, solar-analog stars, and calibration flat-field and argon arc-lamp  images. To produce high quality NIR asteroid reflectance spectra, we  empirically derived the atmospheric extinction coefficients at each  wavelength for each night or portion of the night. To model the atmospheric  extinction over Mauna Kea, the slopes/intercepts of the relationship between the log of the flux (apparent magnitude) vs. airmass were calculated for  each local standard star observation series. The observational procedure to produce the slopes and intercepts required pairing each asteroid with a  nearby solar type star that experienced the same atmospheric conditions  (temporally and spatially). The local standard star and the asteroid  observations were temporally and spatially related as well and were  interspersed within the same air mass range (typically observed at airmasses less than 1.5). The IRTF SpeX instrument uses an argon lamp as its  wavelength reference. Each night several argon arc spectra were obtained for wavelength calibration.   Data Reduction  :  The data were reduced and analyzed at the University of North Dakota. The  obtained raw spectra were in the form of Flexible Image Transport System  (FITS) images. Two software packages were used to process the data: 1) the  Unix-based Image Reduction and Analysis Facility (IRAF) from the National  Optical Astronomy Observatories (NOAO), and 2) SpecPR a Windows-based  program for reduction and analysis of near-infrared spectra stored in  one-dimensional arrays (CLARK 1980; GAFFEY 2003). The extraction of spectra, background sky subtraction, summing the image rows encompassing the object  flux, conversion to text files, and determination of wavelength calibration  were done using IRAF.   Spectral processing using SpecPR involved many important phases to achieve a final, reduced spectrum. Important operations included: 1) calculation of  starpacks from standard stars, 2) channel shifting to account for  instrumental flexure, 3) averaging routines, and 4) data analysis (division  of individual asteroid spectra by the relevant starpack and solar  analog/standard star, polynomial fits, and determination of band  positions/centers/band area ratios). Detailed descriptions of this method  can be found in (FIEBER-BEYER 2010; REDDY 2009; ABELL 2003; HARDERSEN 2003;  GAFFEY 2003; GAFFEY ET AL. 2002). A brief overview of how SpecPR creates a  final, reduced averaged nightly spectrum is as follows: each asteroid  observation was divided at each wavelength by the star flux calculated from  the selected starpack, which not only encompassed the asteroid in airmass,  but also most effectively removed the 1.4 micron and 1.9 micron telluric  water vapor absorption features from the spectrum. Specifically,  atmospheric extinction coefficients (starpacks) are computed from two or  more sets of standard star observations. Extinction coefficients are  determined for all sets of standard star observations (whole night  starpacks), for portions of each night, and for individual sequential sets  of standard star observations.   Starpacks are used to calculate the standard star flux as a function of  wavelength at the same airmass as each asteroid observation. The individual  asteroid flux spectra were divided by the computed standard star flux ratio. The asteroid/star spectrum which most accurately canceled the atmospheric  water vapor absorptions is selected as the best reduction. Since the stars  and the asteroids were measured with the same instrument, the  wavelength-dependent instrumental response was cancelled out when the  asteroid flux measurements were ratioed to the extinction-corrected standard star flux measurements. The solar analog star data were reduced by the same  method and used to correct for any non-solar behavior of the local standard  stars producing a reflectance spectrum. Individual best spectra were reduced by this technique then after inspection for spurious sets - averaged  together to produce a nightly average spectrum for each asteroid. The best  reductions were normalized across a spectral interval to avoid the noise  that may be associated with any individual point in the spectrum. The  normalization value was the average of the values in SpeX channels 380 to  410. (1.5 to 1.7 microns). This interval was chosen because it is  essentially unaffected by either the 1.4 or 1.9 micron atmospheric water  vapor absorptions, or by the mafic silicate absorption feature centered in  the 1.8 to 2.5 micron interval, common in asteroid spectra.   A total of 52 asteroids were included in the survey. The data have been  published in FIEBER-BEYER 2010; FIEBER-BEYER AND GAFFEY 2011; FIEBER-BEYER  ET AL. 2011a; FIEBER-BEYER ET AL. 2011b; FIEBER-BEYER ET AL. 2012;  FIEBER-BEYER AND GAFFEY 2014; FIEBER-BEYER AND GAFFEY 2015. This is an  ongoing survey and data will be added to this archive yearly as they are  published.   Parameter table and Thumbnail Plots  :  A table listing all the spectra with their observational parameters, called  spectraparameters.tab, is provided in the data directory.   Thumbnail plots for browsing the spectra are available in the document  directory. The file thumbnailcumulative.pdf is cumulative with the asteroid spectra arranged in ascending numerical order.    Modification History  :  New to V3.0 are an additional 13 unpublished asteroid spectra obtained  spanning the years 2012 through 2014. The total number of asteroids has been amended in the data set description to reflect a total of 52. Two  publications, one for 2014 and one for 2015, have been added within the data set description to reflect where the data can be found in literature for the asteroids published during these years. The thumbnail.pdf file contains 52  asteroid spectra from the years 2000 through 2014.   References  :  Abell, P.A., Near-IR reflectance spectroscopy of main belt and near-Earth  objects: A study of their composition, meteorite affinities and source  regions. Ph.D. dissertation. Rensselaer Polytechnic Institute, Troy,NY, USA, 2003.   Clark, R.N., A large-scale interactive one-dimensional array processing  system. Publ. Astron. Soc. Pac. 92, 221-224, 1980.   Fieber-Beyer, S.K., Mineralogical characterization of asteroids in/near the  3:1 Kirkwood Gap, Ph.D. Dissertation, University of North Dakota, Grand  Forks, 203 pp, 2010.   Fieber-Beyer, S.K., and M.J. Gaffey, Near-infrared Spectroscopy of 3:1  Kirkwood Gap Asteroids (3760) Poutanen and (974) Lioba. Icarus, 214,  645-651, doi:10.1016/j.icarus.2011.06.014, 2011.   Fieber-Beyer, S.K., M.J. Gaffey, and P.A. Abell, Mineralogical  characterization of Near Earth Asteroid (1036) Ganymed, Icarus, 212,  149-157, doi:10.1016/j.icarus.2010.12.013, 2011.   Fieber-Beyer, S.K., M.J. Gaffey, M.S. Kelley, V. Reddy, C.M. Reynolds, and  T. Hicks, The Maria Asteroid Family: Genetic Relationship and a Plausible  Source of Mesosiderites near the 3:1 Kirkwood Gap. Icarus, 213,  doi:10.1016/j.icarus.2011.03.009, 524-537, 2011c.   Fieber-Beyer, S.K., M.J. Gaffey, P.S. Hardersen, and V. Reddy,Near-infrared  spectroscopy of 3:1 Kirkwood Gap asteroids: Mineralogical diversity and  plausible meteorite parent bodies, Icarus 221, 593-602,  dx.doi:10.1016/j.icarus.2012.07.029, 2012.   Fieber-Beyer, S.K., and M.J. Gaffey, Near-Infrared Spectroscopy of 3:1  Kirkwood Gap Asteroids: A Battalion of Basalts, 44th Lunar and Planetary  Science Conference, LPI Contribution No. 1719, p.1352, 2013.   Fieber-Beyer, S.K., and M. J. Gaffey, M.J., Near-infrared Spectroscopy of  3:1 Kirkwood Gap asteroids II: Probable and plausible parent bodies;  primitive and differentiated, Icarus 229, 99-108,  doi:10.1016/j.icarus.2013.11.001, 2014.   Fieber-Beyer, S.K., and M.J. Gaffey, Near-infrared spectroscopy of 3:1  Kirkwood Gap asteroids III. Icarus, 257, 113-125,  doi:10.1016/j.icarus.2015.04.034, 2015.   Gaffey, M.J., Observational and Data Reduction Techniques to Optimize  Mineralogical Characterizations of Asteroid Surface Materials. Lunar.  Planet. Sci. XXXIV, [abstract 1602], 2003.   Gaffey, M.J., E.A. Cloutis, M.S. Kelley and K.L. Reed, Mineralogy of  asteroids. In Asteroids III (W. F. Bottke, A. Cellino, P. Paolicchi and R.  P. Binzel, Eds.), Univ. of Arizona Press, pp. 183-204, 2002.   Hardersen, P.S., Near-IR Reflectance Spectroscopy of Asteroids and Study the Thermal History of the Main Asteroid Belt. Ph.D. Dissertation. Rensselaer  Polytechnic Institute, Troy, New York, USA, 2003.   Rayner, J. T., D. W. Toomey, P. M. Onaka, A. J. Denault, W. E. Stahlberger,  and 3 others, SpeX: A Medium-Resolution 0.8 - 5.5 micron Spectrograph and  Imager for the NASA Infrared Telescope Facility, PASP 115, 362, 2003.   Reddy, V., Mineralogical Survey Of Near-Earth Asteroid Population:  Implications For Impact Hazard Assessment And Sustainability Of Life On  Earth, Ph.D. dissertation. University of North Dakota, Grand Forks, 2009.

Confidence Level Overview  :  The spectra were obtained over several years (2000-2014); thus, nightly  sky conditions varied. Uncertainties and point to point scatter differ in each asteroid spectrum. The uncertainty in each spectrum is affected by  the level of the signal to noise achieved, changing atmospheric  conditions, and instrument stability. The atmospheric water absorption  bands at 1.4 and 1.9 microns may not be completely removed from the  averaged spectrum. The uncertainties associated with each channel in each asteroid spectrum are standard errors of the mean of the values averaged  to get the reflectance in that channel. These errors are not based on  Poisson statistics, but are instead a measure of systematic variations  among the individual data making up the combined spectrum.  The May 2009 spectra start and end times of observations are listed as  hh:mm as recorded from the observing logs; the fits headers for each  spectrum were not able to be extracted due to a fire shortly after the  IRAF extracted spectrum was transferred to a windows based machine.