Temporal variability of the telluric sodium layer.

The temporal variability of the telluric sodium layer is investigated by analyzing 28 nights of data obtained with the Colorado State University LIDAR experiment. The mean height power spectrum of the sodium layer was found to be well fitted by a power law over the observed range of frequencies, 10 microHz to 4 mHz. The best-fitting power law was found be be 10(beta)nu(alpha), with alpha=-1.

Probing the faintest stars in a globular star cluster.

NGC 6397 is the second closest globular star cluster to the Sun. Using 5 days of time on the Hubble Space Telescope, we have constructed an ultradeep color-magnitude diagram for this cluster. We see a clear truncation in each of its two major stellar sequences.