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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. |