1. 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

2. ARTificial data GONG data
Raw: 512512 pixels images in (,) coordinates     90
0    180 (front side) 181    360 (far side)
 - range:
Duration: min.
Remaped: 700512 pixels in (sin ,) coordinates
No rotation
Filtered with Gaussian function: FWHM = 2.0 mHz, 0 = 3.0 mHz
Raw: 800800 pixels velocity images, two days in January 2004
Duration: min.
Remaped: 700512 pixels in (sin ,) coordinates
Rotation subtracted
Filtered with Gaussian function: FWHM = 2.0 mHz, 0 = 3.0 mHz

3. Cross-correlation function

4. Envelope travel time

5. Envelope travel time

6. Envelope travel time

7. Travel times difference

8. Travel times difference

9. 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