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The contrast of faculae near the solar limb

Wang, H. and Zirin, H. (1987) The contrast of faculae near the solar limb. Solar Physics, 110 (2). pp. 281-293. ISSN 0038-0938. doi:10.1007/bf00206424.

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We have measured the contrast of solar faculae near the limb on direct digital video images made with the 65 cm vacuum reflector at the Big Bear Solar Observatory. We used six broad band filters with different wavelengths from red to violet. The range of heliocentric angle covered in our measurements is 0.05 < μ = cos θ < 0.4 (θ = 87°–66°). About 300 images were measured from observations made during the summers of 1983 and 1985. Over 20000 faculae were measured. By averaging the contrasts of faculae and plotting them vs heliocentric angle, we found that contrast increases monotonically towards the limb for the shorter wavelengths; for longer wavelengths, contrast has a tendency to peak around μ = 0.15, and then decrease towards the extreme limb. The contrast increases as wavelength decreases.

Item Type:Article
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Wang, H.0000-0002-5233-565X
Additional Information:© 1987 Kluwer Academic Publishers. Provided by the NASA Astrophysics Data System. Received 14 October 1986; Revised 16 April 1987. We are grateful to Dr S. Robinson for collecting 1983's data at BBSO and for some valuable suggestions. We also wish to thank the BBSO staff for help in observation. This work was supported by NASA grant NGL 05 002 034 and NSF grant ATM-8513577.
Funding AgencyGrant Number
NASANGL 05 002 034
Subject Keywords:Broad Band; Short Wavelength; Long Wavelength; Video Image; Digital Video
Issue or Number:2
Record Number:CaltechAUTHORS:20200602-083410612
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Official Citation:Wang, H., Zirin, H. The contrast of faculae near the solar limb. Sol Phys 110, 281–293 (1987).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103633
Deposited By: Tony Diaz
Deposited On:02 Jun 2020 15:46
Last Modified:16 Nov 2021 18:23

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