Olga Burtseva and Shukur Kholikov (NSO/GONG) Comparison of Shravan’s artificial data with GONG data (preliminary results) Olga Burtseva and Shukur Kholikov (NSO/GONG) LoHCo meeting – Boulder, 9 November 2006
ARTificial data GONG data Raw: 512512 pixels images in (,) coordinates -90 90 0 180 (front side) 181 360 (far side) - range: 0 - 192 Duration: 1024 min. Remaped: 700512 pixels in (sin ,) coordinates No rotation Filtered with Gaussian function: FWHM = 2.0 mHz, 0 = 3.0 mHz Raw: 800800 pixels velocity images, two days in January 2004 Duration: 1024 min. Remaped: 700512 pixels in (sin ,) coordinates Rotation subtracted Filtered with Gaussian function: FWHM = 2.0 mHz, 0 = 3.0 mHz
Cross-correlation function
Envelope travel time
Envelope travel time
Envelope travel time
Travel times difference
Travel times difference
Conclusion Cross-correlation function of the ART data looks fine, multiple bounces are visible Travel times of the ART data are systematically ~ 6-7 min. shorter than the GONG travel times Travel times of 2nd and 3rd skips of the ART data are not exactly 2 and 3 times longer than 1st skip travel time We found ~1 min. shift in travel times between ingoing and outgoing waves for the ART data Difference between phase and envelope times is more or less constant in 4 skips of the ART data, while it is not the case for the GONG data