36th DPS Meeting, 8-12 November 2004
Session 19 Rings
Poster I, Tuesday, November 9, 2004, 4:00-7:00pm, Exhibition Hall 1A

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[19.18] A Method for Spectral Occultation Data Analysis

E.M. Douglass, A.S. Bosh (Boston Univ.), S. Hylton (M.I.T.)

We have developed a method to remove the background contamination of a bright planetary body from the stellar component of a spectral occultation light curve (a time series of spatially-resolved spectra). Based on the Elliot et al. method (1975 AJ 80, 323) for the removal of the Jovian limb contribution, this revised technique is able to account for a background object’s varying color, such as is observed when a star is occulted by the broad rings of Saturn. This method utilizes color ratios of the star and the occulting body in two wavelength regions. The color ratio of the star is assumed to remain constant throughout the occultation. A high S/N template image of the occulting object is created from data taken before and/or after the occultation. The color ratio of the occulting object can be determined at different locations in the template image. Two wavelength ranges are chosen—where the occulting body dominates and where the star is brightest—and a clean light curve is created. As long as the stellar color is significantly different from the background object color, this method enables observations of occultations by fainter stars than previously allowed with methods such as broadband infrared imaging. We present light curves from the 2002 occultation of the star TYC1310-02402 (K=7.7) by Saturn’s rings. This event was observed at NASA’s IRTF with SpeX (Rayner et al 2003 PASP 115, 362), a medium-resolution spectrograph and imager. This work was supported by NASA Planetary Astronomy grant NNG04GI10G.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.