Infrared Relative Intensity of the Quiet and Active Sun from the Halogen Occutation Experiment

Session 79 - Quiet Solar Photosphere and Chromosphere.
Oral session, Thursday, June 13
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[79.05] Infrared Relative Intensity of the Quiet and Active Sun from the Halogen Occutation Experiment

P. T. Spickler, D. C. Benner (College of William and Mary), I. M. Russell (NASA-Langley)

Data from the Halogen Occultation Experiment (HALOE) provide the first opportunity to examine solar center-to-limb relative intensity measured exoatmospherically at infrared wavelengths between 2.4 and 10 \mum. At each of eight HALOE wavelengths, coefficients to a limb-darkening function are found from data obtained across the solar equator on days of very low solar activity in May 1994. The function produces center-to-limb relative intensities precise to 0.1% (2\sigma). The limb-darkening coefficients are used to calculate disk brightness temperatures and temperature as a function of optical depth. Both of these quantities compare favorably to the model predictions of Varnazza, Avrett, and Loeser (1976, Astrophys. J. Supp. Ser., 30, 1).

HALOE data can also be used to probe the verticle temperature structure of sunspots. At the eight HALOE wavelengths, the relative intensity of a large sunspot is investigated. Umbra/photosphere intensity ratios are obtained for the sunspot and compared to model predictions of Maltby et al. (1986, Ap. J., 306, 1).

Program listing for Thursday