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

Colorado Research Associates Division, NorthWest Research Associates AR 8038 Data available from IVM: : –Not a lot of data, and I believe that there are some calibration files missing. –One “survey” 17:12 UT (1.1'' full FOV, 3 spectral repeats) : –One “survey” 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 : –One 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.

Colorado Research Associates Division, NorthWest Research Associates Final Products and my evaluation of them: (big grain-of-salt on “Final”!) : Survey 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 : Survey UT –Inversion: ok field strength determinations; Haven't looked in detail yet beyond that Time-series 18:00 – 22:00 UT –Initial reaction:

Colorado Research Associates Division, NorthWest Research Associates : 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 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. Final products Cont'd

Colorado Research Associates Division, NorthWest Research Associates 19:31UT 20:02 UT Fringes, seeing, dust specks Penumbral jump in Bz, Jz Bz jumps and line-currents in plage

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

Colorado Research Associates Division, NorthWest Research Associates 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 AR : Bottom line for AR : 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.