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IVM data for 1997 May 09 -- 15

IVM data for 1997 May 09 -- 15. A Study in.... “Region/event was chosen without consideration to IVM data quality” --or-- “Please, please don't make me do this....”. AR 8038 Data available from IVM:. 1997 05 09:

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IVM data for 1997 May 09 -- 15

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  1. IVM data for 1997 May 09 -- 15 A Study in.... “Region/event was chosen without consideration to IVM data quality” --or-- “Please, please don't make me do this....”

  2. AR 8038 Data available from IVM: • 1997 05 09: • Not a lot of data, and I believe that there are some calibration files missing. • One “survey” gram @ 17:12 UT • (1.1'' full FOV, 3 spectral repeats) • 1997 05 15: • One “survey” gram @16:18 UT • There is a short time series 18:00 – 22:00 UT (approx) • Reduced by BJL; raw data (probably?) unavailable, so probably can't re-reduce. • Ambiguity-resolution not yet performed. • 1997 05 12: • One “survey” @ 18:20 UT • Time-series 19:31UT – 21:41 UT, 15 grams, • 0.55'' ½-sized FOV, 2 spectral repeats • Reduced by BJL, ambiguity-resolved by KDL, distributed by KDL • Problems exist: • Unfixable: seeing (terrible!) • KDL re-reducing, working on: • Flat-field incongruity, inversion-induced discontinuities, ambiguity resolution issues in plage regions, time-series inconsistencies.

  3. Final Products and my evaluation of them: (big grain-of-salt on “Final”!) • 1997 05 09: Survey gram @ 17:12 UT • No raw data available, no chance to re-reduce. • Survey 'gram is marginal, appropriate for large-scale qualitative structure evaluation, best if binned by factor 2—4. • Field strengths may be sytemmatically low, noisy; azimuths might show Faraday rotation. • 1997 05 15: Survey gram @16:28 UT • Inversion: ok field strength determinations; Haven't looked in detail yet beyond that. • 1997 05 15 Time-series 18:00 – 22:00 UT • Initial reaction:

  4. Final products Cont'd • 1997 05 12: Survey @18:20 UT • Re-reduced by BJL provides better general sunspot field magnitudes and field directions. Still umbral noise due to lack of photons, and “Triplet with Spots Keyword” inversion produces spurious Jz at penumbral boundaries. • Ambiguity resolution is acceptable. • 1997 05 12 Time Series 1931 – 2141 UT • No matter what: all will have residual fringes and un-corrected(able) dust-specs. • some appear to be acceptable (19:31, 19:40, 19:48, 20:11, 20:43, 21:25, ) in terms of basic data quality. • Others (20:02, 20:19, 20:27, 20:35, 20:51, 20:59, 21:07, 21:33, 21:41) have offsets in Btrans and azimuth of unknown origin that result in large areas that should be below noise being significantly above the noise in Bz and cause serious conniptions for the ambiguity resolution and • “acceptable” and “not acceptable” are my subjective evaluations, usually based on approximately 3-sigma requirements. Those in the “others” list may be used at the 4—5 sigma level; see me for more details as to whether these data will meet your requirements.

  5. 19:31UT Penumbral jump in Bz, Jz Fringes, seeing, dust specks 20:02 UT Bz jumps and line-currents in plage

  6. KD trying some tricks for re-reducing the 1997 05 12 data. Some improvements, some ... not. 19:31 UT Less penumbral jump in Bz, Jz Decrease in fringing Decreased magnitudes of B Completely awful line-currents 20:02 UT

  7. Bottom line for AR8038 1997 05 12: • IVM data can be used to provide Bz boundary condition • (Allow KD to temporally select and average a bunch for best results) • IVM data can be used to provide B as a boundary condition • (Allow KD to temporally select and average a bunch for best results) • IVM data probably should not be used as a time-series • Caveat #1: probably ok for select magnetograms • Caveat #2: possibly ok for qualitative characteristics of Bz Bottom line for AR8038 1997 05 09--15: • IVM data can be used to provide Bz boundary condition • IVM data probably can be used for a day-to-day time series for evolution of not only Bz but B, too. • Caveat #1: probably best if additional binning performed for better signal/noise.

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