GONG Newsletter #31, August - National Solar Observatory

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Hats off to our deployment teams – they have done a lot of traveling in the last ve months and have done a great job. The Project has had some comings and goings in the GONG team here in Tucson. Susan Davidson, who was with GONG for over six years, and NOAO for nearly 25 years, retired at the beginning of February. She will be missed throughout the GONG GONG+ Instrument Team members (from left to right): community, and we wish her Jean Goodrich, Roberta Toussaint, Roy Tucker, the very best in the future. Sang Nguyen, Guillermo Montijo, Lana Britanik, Bert Villegas, Ron Kroll, and Jack Harvey Roberta Toussaint, who has been with GONG for nearly a decade, has moved over to NSO’s SOLIS Project. We look forward to her continued association with GONG, which has included her participation in the GONG+ deployment. We also saw Tatia Wing move on and wish her the best in her new adventures. David Landy will be leaving at the end of the summer and setting new goals as a graduate student at Indiana University. in the production and deployment of GONG Classic, and it is great to have him back on the team. Katrina Gressett, Simon Kras and Kerri Donaldson Hanna joined the DMAC group, and Jeffrey Sudol will be working with the Instrument Team. Kiran Jain, from the Udaipur Solar Observatory, visited Tucson in February and March of this year, and was one of the rst GONG+ users, producing ring diagrams in both velocity and intensity. On the positive side of the ledger, Caroline Barban joined the Analysis Group and is working on improving the mode parameter estimates by simultaneously tting the spectrum obtained in velocity and intensity. Guillermo Montijo was welcomed back into the fold. As many of you remember, he was a key player A cut through 3-dimensional power spectra at 3.5 mHz for the velocity (left panel) and intensity (right panel). The spectra were generated by tracking a 20° by 20° region for 2 days as it crossed disk center. Each gure extends ± 2.2 Mm -1 k x and k y . GONG-SOHO 2002 Big Bear Solar Observatory - October 2002 Final dates and meeting information to follow via email, snail mail, and the GONG www server. The GONG bibliography is being integrated into the Astrophysics Data System at http://adsabs.harvard.edu/Groups/search/Helioseismology or on the main ADS search form. Keep your pre/reprints coming.
What Data Can I Get from GONG GONG provides data freely to its members. Becoming a member is simple — go to the GONG web page and select the “Scientic Enterprise” link and then the “GONG Membership Application” link and then the “GONG Research Program Application” link. You can ll out the forms electronically, or by using a text le. After the forms are submitted and processed, you will be able to search and order our data. Some of the currently available products for the helioseismologist are: Power spectra of solar oscillations covering the range of 0 ≤ l ≤ 200, -l ≤ m ≤ +l, and 0 ≤ ν ≤ 8.33 mHz. Time series of complex spherical harmonic coefcients as a function of l and m in the range 0 ≤ l ≤ 200 and 0 ≤ |m| ≤ l. Estimated frequencies, amplitudes, and linewidths of solar oscillation modes, as a function of l, m, and ν covering the range 0 ≤ l ≤ 150, -l ≤ m ≤ +l, and 1.2 ≤ ν ≤ 4.0 mHz. Both the time series and power spectra are available for temporal intervals of GONG months (GM), with 1 GM ≡ 36 days. Note, however, that the mode parameters are computed from overlapping three-GM (108 day) temporal intervals, with a one-GM spacing. Time series and power spectra are also available for 0 ≤ l ≤ 45 for intervals of 1 GONG Year (10 GM or 360 days) and 35 GM. All data from 7 May 1995 to 6 October 2000 have been processed to time series and power spectra, and the mode parameters have been computed on all possible 53 intervals of 3 GM. For the non-helioseismologist, we have: • Minute-by-minute images of the solar surface Doppler velocity eld from 7 May 1995 to the present. • Magnetograms every 20 minutes, plus derived synoptic maps for Carrington rotation cycles 1896 through 1942; and • Low-pass, temporally ltered, and geometrically registered images of the surface Doppler velocity with a cadence of 4 minutes and a lter width of 17 minutes, useful for studies of slowly evolving ows from 7 May 1995 to 17 October 1998. Finally, we have implemented a new data service that provides near-real-time magnetograms with rough calibration and a cadence of about one every two hours around the clock. They can now be obtained at: ftp://www.gong.noao.edu/pub/gong/magnetograms Sasha Kosovichev called attention to changes in GONG+ observations of the X20 are of April 2, 2001 in NOAA 9393, and Jack Harvey prepared this gure to show the temporal evolution. The left panel is the line-of-sight component of the magnetic eld near the northeast limb averaged over 30 minutes prior to the are (2100-2129 UT). The next six panels show the difference between the absolute value of the signal averaged over subsequent ten minute periods and the 30 minute pre-are average. White (black) represents increasing (decreasing) line-of-sight signal strength. The panels are averaged from left to right over 2130-39 (preare), 2140-49 (rising phase), 2150-59 (maximum), 2200-09 and 2210-2219 (declining phase), and 2250-59 (post are). The changes shown are a combination of seeing effects, change in perspective as the Sun rotates, line prole changes associated with the maximum phase of the are, normal evolution of the active region eld, and real eld changes associated with the are. The later panels are coincident with a strongly sheared sunspot. It is not clear if the are eld changes are in strength, direction or position or some combination.
Page 1: Newsletter Number 31 July 2001 GONG

GONG Newsletter #31, August - National Solar Observatory

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