AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 93. Quiet Photosphere, Chromosphere and Transition Region
Display, Thursday, June 3, 1999, 9:20am-4:00pm, Southeast Exhibit Hall

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[93.11] HRTS Observations of Solar Fine Scale Structures in the Near-UV

J. S. Morrill, K. P. Dere, C. M. Korendyke (E.O. Hulburt Ctr. for Space Research, NRL)

The NRL High Resolution Telescope and Spectrograph (HRTS) obtains ultraviolet spectra, ultraviolet spectroheliograms and H alpha spectroheliograms at a spatial resolution of about 1 arc-second along a 900 arc-second slit. The HRTS-9 rocket flew on April 18, 1995 during the declining phase of the solar cycle. The HRTS-9 instrument and observing program were tailored to observe emission patterns inthe ultraviolet for the purpose of studying solar variability. Observation targets included the quiet sun, active regions and the quiet limb. The wavelength range of HRTS-9 spectrograph was from ~275 nm to ~290 nm. Some of the prominent spectral features in this wavelength range are the Mg II h and k lines at ~ 280 nm, the strong Mg I Fraunhofer line at ~285 nm, and the continuum. The ultraviolet spectroheliograph obtained images of a portion of the sun at wavelengths corresponding to a range of temperatures: 1550 (C IV), 1540 (Si I), 1560 (C I), and 1600 (continuum).

The primary goal of the HRTS-9 rocket program was to examine the origin of the total solar variability in the intensity variations of solar structures in the near ultraviolet on a variety of spatial scales. The HRTS-9 data reveals the fine structure of the quiet sun, plage, and sun spots in the near ultraviolet. In addition, active region contrast factors are determined for comparison with modes of full disk ultraviolet variability based on SUSIM and SOLTICE observations from UARS.

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