IRS-TR 12003: Constructing Low-Resolution Truth Spectra of the Standard Stars HR 6348 and HD 173511

This report describes the generation of fully calibrated spectra of the K giants HR 6348 and HD 173511 from data obtained with the low-resolution modules of the Infrared Spectrograph (IRS), with an emphasis on the spectra from the Long-Low (LL) module. The spectra were calibrated using Kurucz models and IRS observations of the A dwarfs α Lac and δ UMi. The calibration process required mitigation for fringing in the first-order LL spectrum and a faint red excess in α Lac which may arise from a low-contrast debris disk. The final calibrated spectrum of HR 6348 has a spectroscopic fidelity of 0.5% or better below 29 μm, with an uncertainty increasing to ∼1% at 33–37 μm. The final calibrated spectrum of HD 173511 has a spectroscopic fidelity of ∼0.5% at all wavelengths below 35.8 μm.