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Session 14 - Solar-Terrestrial, Solar Wind.
Oral session, Monday, June 30
Ballroom A, Chair: David Webb

[14.03] An Analysis of the Blue and Red Contrasts of Photospheric Faculae

G. A. Chapman, S. Ahern (SFO/CSUN)

Full disk images have been obtained with the Cartesian Full Disk Telescope 2 (CFDT2) at the San Fernando Observatory, beginning in 1992 July to the present. This system produces digital, photometric images with 2.5" pixels. Images from this system for 110 days during the summer months of 1993, 1994 and 1995 have been used in this analysis. The images used were obtained in the Ca II K-line, in the blue at 470.6 nm, and in the red at 672.3 nm. The Ca II K-line images were used only to locate facular pixels, identified as those with a contrast of 4.8% or higher. The co-aligned K-line images permit the unbiased detection of low contrast faculae in the blue and red images. In all three filters, the facular pixel contrasts showed an increase proportional to 1/\mu. Contrasts near disk center in the K-line, blue and red filters were found to be about 7%, 0.12%, and 0.13%, rising to about 25%, 12% and 8%, respectively, at \mu = 0.2, the limit of analysis. The change of contrast as a function of \mu tend to support the "hot wall" model for facular emission. We thank the many student observers and staff who helped obtain the images used here. This work has been partially supported by NASA grant NAGW-3017 and NSF grant ATM-9504374.

Reference Ahern, Sean, M.S. Thesis, CSU, Northridge (August 1996).


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