Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/5733
Title: Line-of-sight observables algorithms for the helioseismic and magnetic imager (HMI) Instrument Tested with Interferometric bidimensional spectrometer (IBIS) observations
Authors: Couvidat, S
Rajaguru, S. P
Wachter, R
Sankarasubramanian, K
Schou, J
Scherrer, P. H
Keywords: Sun: helioseismology;Instrument: SDO/HMI, IBIS
Issue Date: May-2012
Publisher: Springer
Citation: Solar Physics, Vol. 278, No. 1, pp. 217-240
Abstract: The Helioseismic and Magnetic Imager (HMI) instrument onboard the Solar Dynamics Observatory produces line-of-sight (LOS) observables (Doppler velocity, magneticfield strength, Fe I line width, line depth, and continuum intensity) as well as vector magnetic-field maps at the solar surface. The accuracy of LOS observables is dependent on the algorithm used to translate a sequence of HMI filtergrams into the corresponding observables. Using one hour of high-cadence imaging spectropolarimetric observations of a sunspot in the Fe I line at 6173 Å through the Interferometric Bidimensional Spectrometer installed at the Dunn Solar Telescope, and theMilne–Eddington inversion of the corresponding Stokes vectors, we test the accuracy of the observables algorithm currently implemented in the HMI data-analysis pipeline: the MDI-like algorithm. In an attempt to improve the accuracy of HMI observables, we also compare this algorithm to others that may be implemented in the future: a least-squares fit with a Gaussian profile, a least-squares fit with a Voigt profile, and the use of second Fourier coefficients in the MDI-like algorithm.
Description: Restricted Access
The original publication is available at springerlink.com
URI: http://hdl.handle.net/2248/5733
ISSN: 0038-0938
???metadata.dc.rights???: © Springer
???metadata.dc.relation.uri???: http://dx.doi.org/10.1007/s11207-011-9927-y
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