SOHO CoRoT Kepler Picard SDO GONG
bandeau

Ring-diagram frequency comparisons for GONG, MDI and HMI

Auteur

Howe Rachel

Institution

National Solar Observatory

Theme

Local helioseismology
Auteur(s) supplémentaire(s)F. Hill, R. Komm, S. Tripathy, R. Bogart, D. Haber
Institution(s) supplémentaire(s)Stanford University, University of Colorado

Abstract

We compare mode frequencies from ring diagram
analysis of GONG and MDI data carried out as part of the preparation for
HMI, and also from some preliminary tests of HMI data. In all cases, there are systematic variations with disk position as well as changes due to local magnetic activity. We find that there is a consistent GONG/MDI difference that varies across the solar disk due to incompletely corrected MDI image distortion.
We also check for
effects on the inferred mode frequencies
of tracking at the Carrington rather than the Snodgrass rate.


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