We present spectra obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope of 33 K giants and 20 A dwarfs to assess their suitability as spectrophotometric standard stars. The K giants confirm previous findings that the strength
of the SiO absorption band at 8 um increases for both later optical spectral classes and redder (B-V)_0 colors, but with considerable scatter. For K giants, the synthetic spectra underpredict the strengths of the molecular bands from SiO and OH. For these reasons, the assumed true spectra for K giants should be based on neither the assumption that molecular band strengths in the infrared can be predicted accurately from optical spectral class or color nor synthetric spectra. The OH bands in K giants grow stronger with cooler stellar temperatures, and they are stronger than predicted by synthetic spectra. As a group, A dwarfs are better behaved and more predictable than the K giants, but they are more likely to show red excesses from debris disks. No suitable A dwarfs were located in parts of the sky continuously observable from Spitzer, and with previous means of estimating the true spectra of K giants ruled out, it was necessary to use models of A dwarfs to calibrate spectra of K giants from observed spectral ratios of the two groups and then use the calibrated K giants as standards for the full database of infrared spectra from Spitzer. We also describe a lingering artifact that affects the spectra of faint blue sources at 24 um.
We present 75x75 size maps of M82 at 6.4 micron, 6.6 micron, 7.7 micron, 31.5 micron, and 37.1 micron with a resolution of ~4 that we have obtained with the mid-IR camera FORCAST on SOFIA. We find strong emission from the inner 60 (~1kpc) along the m
ajor axis, with the main peak 5 west-southwest of the nucleus and a secondary peak 4 east-northeast of the nucleus. The detailed morphology of the emission differs among the bands, which is likely due to different dust components dominating the continuum emission at short mid-IR wavelengths and long mid-IR wavelengths. We include Spitzer-IRS and Herschel/PACS 70 micron data to fit spectral energy distribution templates at both emission peaks. The best fitting templates have extinctions of A_V = 18 and A_V = 9 toward the main and secondary emission peak and we estimated a color temperature of 68 K at both peaks from the 31 micron and 37 micron measurement. At the emission peaks the estimated dust masses are on the order of 10^{4} M_sun.
