Contrast of faculae near the disk center and solar variability

摘要: We analyze simultaneous, or near-simultaneous, coregistered, digital, photometric images of solar photospheric intensity and line-of-sight magnetic field. Images were made with the Lockheed tunable filter instrument at Swedish Solar Observatory, La Palma, video spectra-spectroheliograph system San Fernando Observatory new NASA spectromagnetograph National Kitt Peak. study disk center contrasts small elements. While active region faculae are dark quiet Sun network features bright. The populations field elements that make up these two kinds quite different. Different contrast center-limb functions must be used when estimating their irradiance luminosity contributions. color dependent indicate a depth effect related to H− opacity facular atmosphere. This result is important for calibration monochromatic observations bolometric fluctuations. emphasize value cooperative among installations whose differing strengths complementary.