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Powders of nanocrystalline metal oxides were compared with common macrocrystalline powders and minerals for their ability to reflect near-infrared light (NIR) (750−2500 nm). The nanocrystalline metal oxides were found to possess higher NIR reflectance values (∼15−20%) and this can be attributed to their smaller crystallite sizes coupled with smaller mean aggregate sizes in accordance with the Kubelka−Munk theory.

We present a compilation of UBVRIz light curves of 51 type II supernovae discovered during the course of four different surveys during 1986-2003: the Cerro Tololo Supernova Survey, the Calán/Tololo Supernova Program (C&T), the Supernova Optical and Infrared Survey (SOIRS), and the Carnegie Type II Supernova Survey (CATS). The photometry is based on template-subtracted images to eliminate any potential host galaxy light contamination, and calibrated from foreground stars. This work presents these photometric data, studies the color evolution using different bands, and explores the relation between the magnitude at maximum brightness and the brightness decline parameter (s) from maximum light through the end of the recombination phase. This parameter is found to be shallower for redder bands and appears to have the best correlation in the B band. In addition, it also correlates with the plateau duration, being shorter (longer) for larger (smaller) s values.

Optical light curves and spectra of the Type la supernova 1986G in NGC 5128 (Centaurus A) are presented. SN 1986G was discovered approximately one week before maximum light. The initial rate of decline of the B light curve was remarkably fast and characteristic of the infrequently observed Pskovskii photometric class ß = 12. Although the spectral evolution closely resembled that of the more common "slower" photometric classes of Type la supernovae, subtle differences in the maximum-light spectra were detected. The expansion velocity of the photosphere of SN 1986G decreased rapidly at early phases, suggesting that the outer-envelope density gradient was less steep than in supernovae with smaller values of ß. SN 1986G appears to have been heavily obscured (E(B -V) = 0.90 ± 0.10) by the dust lane of NGC 5128. This circumstance accounts for the strong interstellar-absorption lines of Ca n H and K and Na ID observed in the spectra as well as for several weaker absorption features that we identify with the diffuse interstellar bands.SN 1986G provides graphic confirmation of the existence of intrinsic differences in the optical light curves and spectroscopic properties of Type la supernovae. Consequently, these objects must be used with considerable caution as cosmological standard candles. On the basis of the very close resemblance of SN 1986G to SN 19711 in NGC 5055, we derive a relative distance of D NGC5128 / D NG c5055 = 0.39 ± 0.04. Further distance estimates are hampered due to the lack of other well-observed Type la supernovae with ß = 12.