An improved determination of the area ratio of faculae to sunspots

We report new results on the ratio of facular area to sunspot area from a program of continuing photometric observations using the Cartesian Full Disk Telescope No. 1 (CFDT1) at the San Fernando Observatory (SFO). The facular areas are determined from images obtained with a 1 nm bandpass Ca II K line filter, and sunspot areas are determined from red images at 672 nm with a 10 nm bandpass filter. On the K line images faculae were identified by pixels that had a contrast equal to or greater than 4.8% divided by mu. Previously, we found that the average facular-to-spot area ratio was 16.7 +/- 0.5 during the latter part of solar cycle 22 and that there was a small but statistically significant rise in the ratio with time. If we take an average from the beginning of the K line data (mid-1988) until the middle of 1996, excluding days of zero sunspot area, the average ratio is 16.4 +/- 0.4. The average ratio from mid-1996 to the end of 1999 November is 12.6 +/- 0.5. Including days of zero sunspot area for these same intervals we find average ratios of 16.8 +/- 0.5 and 13.2 +/- 0.6, respectively. We have recently reprocessed our K line images, which have been photometrically "cleaned." We can now reliably identify facular pixels with a contrast criterion of 2.4%, resulting in an increase in the average facular-to-spot ratio of approximately 3. The average facular and sunspot areas for cycle 23 are significantly lower than for cycle 22.