Computer Science – Sound
Scientific paper
Jan 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995phdt........30m&link_type=abstract
Thesis (PH.D.)--THE JOHNS HOPKINS UNIVERSITY, 1995.Source: Dissertation Abstracts International, Volume: 57-01, Section: B, page
Computer Science
Sound
1
Silicon Carbide, Stellar Calibration
Scientific paper
Two separate far ultraviolet observations of the nighttime airglow are described. One observation is made near solar minimum (April 14, 1994) with the current version of the Johns Hopkins University Faint Object Telescope sounding rocket payload. Detailed discussion is made of the design, development and application of the instrument and associated experimental techniques, including the use of silicon carbide ion-deposited over aluminum on all the telescope mirror optics. Reflectivity of over 30% per surface is obtained from 800 A to 1600 A, with excellent long-term stability, showing negligible degradation after the first few months to over a period of 2 full years. An evacuated far ultraviolet spectrograph and detector system with point source resolution of ~4 A is described. The other observation is made at solar maximum (December 9, 1990) using the Hopkins Ultraviolet Telescope aboard the Astro-1 space shuttle mission. The Lyman-alpha and Lyman-beta intensities in both sets of data are interpreted with a geocoronal radiative transport model (Anderson and Hord, 1977; Anderson et al., 1987; Bishop, 1995). The simultaneous observation of Lyman-alpha and Lyman-beta provides a sufficient constraint on the model atmosphere to allow determination of the solar Lyman-alpha and Lyman -beta fluxes as well as the interplanetary medium brightness contribution to the nightglow. During the HUT observation, the Lyman-alpha solar flux is determined to be 4.39 +/- 0.64 times 1011 photons cm ^{-2} s^ {-1} with a Lyman-beta solar flux of 6.0 +/- 1.2 times 10^9 photons cm^{-2} s^{-1}. The solar fluxes during the FOT observation were determined to be 3.35 +/- 0.59 times 1011 photons cm^{-2} s ^{-1} and 4.3 +/- 1.4 times 10^9 photons cm ^{-2} s^{-1 } for Lyman-alpha and Lyman-beta, respectively. The interplanetary medium brightness for Lyman-alpha was 545 Rayleighs during the HUT mission in the (interstellar) downwind, anti-solar direction, +45^circ above the solar ecliptic and 489 Rayleighs during the FOT observation, from the interstellar wind side of the sun, looking downwind, but +79^circ above the solar ecliptic.
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