European Helio- and Asteroseismology Network (HELAS)

    Local Helioseismology Network Activity








    Travel Time Maps

    Files include: the original 1664 minutes of MDI tracked Dopplergrams; 512 minute datacube extracted from the original; mean travel time maps of various active regions from the 512 minute dataset; and the sound speed inversions of the mean travel time maps calculated by S. Zharkov for AR 7973, 8038, 9056, 9138, 9142, 9779.
    Time: 24 hours each

    Resolution: 0.125 degrees / pixel

    Dimensions: 128 x 128 x 512 pixels

    Parameters

    Low Pass filter 5.2mHz with FWHM 0.2
    Travel times were obtained using center to annulus geometry, with annulus thickness equal to 3 data pixels, i.e. 3*1.51815.
    r1 is the spatial resolution of the MDI data, i.e. just the value of .125 degrees per pixel translated into MM per pixel.
    List of central skip-distances and corresponding phase-speed filter parameters used:

    skip-distance  phasespeed flt v0   phasespeed flt dv0
5.83            14.21                 2.63  
7.29            15.40                 2.63  
11.664          17.49                 3.33  
16.038          25.82                 3.86  
20.412          30.46                 3.86  
24.786          35.46                 5.25  
29.16           39.71                 3.05  
33.66           43.29                 3.15  
37.91           43.29                 3.15  
42.28           47.67                 3.57  
46.66           57.16                 3.78  
51.01           57.16                 3.78

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