Ultraviolet spectroscopy of the chromosphere and transition zone at high spatial and temporal resolution

The third rocket flight of the NRL High Resolution Telescope and Spectrograph (HRTS) recorded UV spectra of the quiet Sun in a 10″ × 800″ region. By rastering the slit in 2′' increments, a time series with 20s resolution of two-dimensional spectra with 1′' spatial resolution was obtained. The spectrum includes strong chromospheric diagnostic lines of C I, Si I, and Fe II, transition zone lines of C IV and the continuum which is produced in the temperature minimum. Images of the network show that Fe II emission is well-correlated with dark Hα mottles, that the transition zone is produced in extended structures which are apparently continuations of the mottles, and that the strongest continuum emission is from near the base of the mottles. Time series of C I profiles show little variation in most features aside from the chromospheric jets which develop rapidly over timescales of 30s. The C IV profiles also show only gradual variations over most of the slit except for the numerous small explosive events.