1. Mapping active regions in the Far Side of the Sun using helioseismology I. González Hernández, F. Hill (1) C. Lindsey and D. Braun (2) (1) National Solar Observatory, Tucson, AZ (2) NorthWest Research Associates, Boulder, CO

2. Contents Helioseismic holography of the Far Side of the Sun: a quick review. Helioseismic holography of the Far Side of the Sun: a quick review. Prediction capability: NOAA10808 & NOAA10923 Prediction capability: NOAA10808 & NOAA10923 Calibration of far-side seismic holography signal Calibration of far-side seismic holography signal “Far-side” imaging of the near side “Far-side” imaging of the near side CME and Flare connection CME and Flare connection Conclusions and future work Conclusions and future work

3. Courtesy of D. Braun EARTHEARTH Far Side Seismic Holography Helioseismic imaging of sunspots at their antipodes. Lindsey, C. & Braun, D.C, 1990, SoPh. Helioseismic imaging of sunspots at their antipodes. Lindsey, C. & Braun, D.C, 1990, SoPh. Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science. Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science. Pupil

4. GONG near-real-time data Continuous stream of velocity images Continuous stream of velocity images Quick calibration done at the sites Quick calibration done at the sites 215x215 Gaussian-smoothed velocity images 215x215 Gaussian-smoothed velocity images Transfer daily from six GONG stations Transfer daily from six GONG stations Images merged in Tucson Images merged in Tucson http://gong.nso.edu/quickreduce/quickpulse.html Farside maps calculated from 1440-min data series twice daily. Farside maps calculated from 1440-min data series twice daily. Maps calculated approx. 12 hours after the last image has been taken. Maps calculated approx. 12 hours after the last image has been taken. Recalculated if the duty-cycle increases due to extra transfer. Recalculated if the duty-cycle increases due to extra transfer. Full-hemisphere farside maps. Full-hemisphere farside maps. http://soi.stanford.edu/farside http://gong.nso.edu/data/farside

5. Prediction capability Carrington Longitude sin(latitude) Active Region NOAA-10808 Aug 29 -> Sep 9 2005 AR10808 Active Region NOAA-10923 Oct 31 -> Nov 10 2006 AR10923 sin(latitude)

6. Calibrating the far-side signal

10. “far-side” imaging of the near side Braun & Lindsey 2001, ApJ, 560, L189 NOAA 10808 (far side) NOAA 10808 (near side)

11. “far-side” imaging of the near side 1 x 3 skip method actually extends well onto the near side! can fill in some of this area with 1 x 4 skip method (in progress…)

12. CME and Flare connection

13. The left panel shows overlaid on the C2 LASCO image the front side of the Sun taken by the EIT instrument. The right panel shows the calculated farside map for that day as seeing from Earth perspective, i.e. looking directly through the Sun. ”….By 00:24 UT, signature of a huge and apparently backsided CME can be seen all above the E Limb (most likely related to Event #2). Though the timing seems to match that of the event from AR 10806, the event off limb is most probably from the back side of the Sun. In summary, the event as a whole can be determined as an asymmetric full halo CME. Several components contribute to the overall shape of the complex event, at least one of them frontsided, associated with a B-class X-ray flare on NOAA AR 10806. However, the bigger contribution seems to have its origins on the backside” (G. Stenborg, SOHO-LASCO Operations Scientist). AR10806 AR10808

14. using both far-side and near-side images to understand physics of phase-shifts/travel-times 2 mHz 3 mHz 4 mHz 5 mHz travel-time pert. (sec) Braun & Birch 2007 (in prep.) understanding physics can: lead to better calibration of far-side signatures lead to improved models of subsurface structure lead to detection of emerging ARs

15. Conclusions and future work Space weather: Space weather: MDI and GONG pipelines are providing daily full-hemisphere farside maps. MDI and GONG pipelines are providing daily full-hemisphere farside maps. Large active regions are seen in consecutive far-side maps. Large active regions are seen in consecutive far-side maps. Scientific Calibration Scientific Calibration Empirical calibration: Statistics with far-side results +front-side analysis Empirical calibration: Statistics with far-side results +front-side analysis Calibration of artificial “sunspots” Calibration of artificial “sunspots” Calibrate effect of several bounces and dispersion relation Calibrate effect of several bounces and dispersion relation Ghost signature --> solar features? Ghost signature --> solar features? Collaboration with irradiance variation studies Collaboration with irradiance variation studies