1 GONG Magnetogram Data Products

2 Sky-coordinate images Single-site or merged? –Single-site requires users to select. –Merge has lower noise, may require site- specific correction to reduce jumps as stations change. At what cadence? –1 min – highest cadence, most noise. –3 min or 5 min – compromises. –10 min – lowest cadence, least noise, rotational smearing starts to be a concern. Rotational smearing correction? How? –Rotation crosses 1 pixel at disk center in about 15 min. –Remap and average in heliographic coordinates, transform back to sky. What temporal filter/averaging algorithm? –Simple box car. –Hathaway filter (Gaussian). –Will need to specify width in any case.

3 Remapped images Same questions as for sky images: –Single-site/merged –Cadence –Rotational smearing easy to deal with –Temporal filter What spatial resolution for remapped images? –Currently 0.2° What projection for remapped images? –Currently longitude - sine latitude

4 Synoptic Maps Single-site or merged? At what cadence –Trade-off between effort and science: What’s rapid enough for space weather? –1, 2, 4, 8 hours? How to interact with SOLIS cadence? –Identical times for comparison? –Different times to fill in temporal gaps ? How to treat poles, projection of LOS, missing data?