Simultaneous Velocity-Intensity Fitting

Simultaneous Velocity-Intensity Fitting We use 9 GONG months (324 days, from 1996 Oct. 28 to 1997 Sept. 16, duty cycle=85%) of I (Intensity) and V (Velocity) rotation corrected, m-averaged spectra corresponding to l=15-50 between 1.6 and 4.8 mHz (617 modes) to determine the solar oscillation parameters. These parameters are determined by fitting simultaneously 4 spectra: V and I power, I-V phase difference and I-V coherence using the model of Severino et al. (2001). More details are in Barban et al. (2003)..
	The figure at left shows the good fit to the observed spectra for the l=24, n=9 mode, with the dots showing the data and the curves the fit.
	Here we show the modeled helioseismic spectra for l=24, n=9, demonstrating the sensitivity to the background components. The solid line corresponds to the best fit; the dashed line to the same model with the coherent uncorrelated background set to zero both in I and V, and the dotted line to a model with the coherent correlated background set to zero. The absolute oscillation frequency difference is less than 0.1 microHz between 1.6 and 3.2 mHz.