Recently, we have set up a new digital CCD camera system, MicroMax YHS-1300 manufactured by Roper Scientific for Hα observation by Solar Flare Telescope at Bohyunsan Optical Astronomy Observatory. It has a 12 bit dynamic range, a pixel number of 1300×1030, a thermoelectric cooler, and an electric shutter. Its readout speed is about 3 frames per second and the dark current is about 0.05 e-/p/s at -10°. We have made a system performance test by confirming the system linearity, system gain, and system noise that its specification requires. We have also developed a data acquisition software which connects a digital camera con-troller to a PC and acquires Hα images via Microsoft Visual C++ 6.0 under Windows 98. Comparisons of high quality Hα images of AR 9169 and AR 9283 obtained from SOFT with the corresponding images from Learmonth Solar Observatory in Australia confirm that our Hα digital observational system is performed properly. Finally, we present a set of Hα images taken from a two ribbon flare occurred in AR 9283.

We have analyzed infrared (IR) images of Jupiter which was observed at the McDonald Observatory, Texas, U.S.A., during the P/SHoemaker-LEvy 9 (SL9) impact period and about one week after the last impact. The IR images were obtained on the 2.7m telescope using a NICMOS array with filters to isolate the 1.5 μm NH3 band, the 2.3 μm CH4 band, the 2.12 μm H2 S(0) pressure-induced absorption, and the continua at 1.58 μm and 2.0 μm (short K-band). All images except those with the 1.58 μm continuum filter show bright impact sites against the relatively dark Jovian disk near the impact latitude of about 45° S. This implies that dusts originated from the impacts reflect the solar radiation at high altitudes before absorbed by stratospheric CH4, NH3 or H2. The impact sites observed with the 2.3 μm filter are conspicuously bright against a very dark background. The morphology of impact sites, G, L, and H at 2.3 and 2.12 μm filters shows clearly an asymmetric structure toward the incident direction of the comet fragments, in agreement with the studies of visible impact images obtained with the Hubble Space Telescope. Comparisons of reflectances of G, L, and H sites with simple radiative transfer models suggest that optically thick dust layers were formed at high altitudes at which methane absorption attenuates incoming sunlight only by about 1%. The dust layers in these sites seem to form at about the same altitude regardless of the magnitude of the impacts, but they appear to descend gradually after the impacts. The dust layers have optical depths of 2-5, according to the models.