A Caltech Library Service

A 10-Year Set of Ca II K-Line Filtergrams

Johannesson, Anders and Marquette, William H. and Zirin, Harold (1998) A 10-Year Set of Ca II K-Line Filtergrams. In: Solar Electromagnetic Radiation Study for Solar Cycle 22. Springer , Dordrecht, pp. 265-278. ISBN 978-94-010-6099-8.

Full text is not posted in this repository. Consult Related URLs below.

Use this Persistent URL to link to this item:


We have processed a 10-year set of BBSO Ca II K-line filtergrams covering most of solar cycle 22. The excess K-line emission is integrated to form linear and square-root activity indices that are fitted to UV data from UARS and SME. Good fits are found both for the Mg II core-wing ratio (linear) and total Lα irradiance (square root) and the indices are thus good proxies for UV data. The SME Lα irradiance is systematically lower by 20% than predicted from our corresponding K-line indices. The 10.7 cm radio data confirms that SME underestimated the flux. The network is partly responsible for the solar cycle variation of the indices and is relatively more important in Lα than in Mg II and Ca II K. This is due to the saturation of Lα equivalent width. We also report on substantial improvements to the equipment and reduction software. The system is now based on a digital CCD camera which promises more accurate measurements in the upcoming solar cycle 23.

Item Type:Book Section
Related URLs:
URLURL TypeDescription ReadCube access ItemJournal Article
Additional Information:© 1998 Springer Science+Business Media Dordrecht. Paper presented at the SOLERS22 International Workshop, held at the National Solar Observatory, Sacramento Peak, Sunspot, New Mexico, U.S.A., June 17–21, 1996. The UARS data were provided courtesy of the NASA UARS project by Drs. Gary Rottman and Guenter Brueckner. This research is funded by the Upper Atmosphere Research Program of NASA under grant NAG5-2782. The purchase and installation of the new camera and the new optical layout were funded by grant NSF ATM-9303508 of the RISE program. We are indebted to Dr. H. Lin for providing flatfielding software. SME satellite data are courtesy of the University of Colorado. The 10.7 cm radio flux data are provided by the National Research Council of Canada. We also thank Drs. Oran White, Judith Lean and Judit Pap for helpful discussions. HZ wishes to dedicate his participation in this paper to an anonymous NSF referee who predicted, 'We will never see digital data from the Big Bear Solar Observatory.'
Funding AgencyGrant Number
Subject Keywords:Solar Cycle; Equivalent Width; Versus Index; Solar Image; Solar Cycle Variation
Record Number:CaltechAUTHORS:20200716-140545879
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104410
Deposited By: Tony Diaz
Deposited On:16 Jul 2020 21:36
Last Modified:16 Nov 2021 18:31

Repository Staff Only: item control page