An analysis of full-disk observations of facular contrast in the blue and red

摘要: Full-disk images from the Cartesian Full-Disk Telescope no. 2 (CFDT2) were used to study center-to-limb (CLV) variation of facular contrast in two colors. The CFDT2 images, which have 2.5 arc sec pixels, obtained during summer months 1993, 1994 and 1995. In order minimize bias finding faint features continuum we coaligned Ca K-line identify faculae. Faculae sorted into 20 annular bins equal width. To reduce effects seeing, faculae not identified closer limb than μ=0.2. pixel contrasts fitted various trial functions. blue filter (470.6 nm) rose 0.122% at disk center 12.2% red (672.3 nm) 0.13% 8.16% We also analyzed multiplied by their μ-value obtain an estimate flux tube contrasts. These increased roughly linearly μ=0.95 0.25. reached a maximum 2.48% near μ=0.25. 1.59% values are corrected for filling factor. curve leveled off slightly betwen μ=0.25 0.2 while showed no deviation its linear trend. results may provide some support hot wall model tubes.