HARP active-region patch ID
HARP means HMI Active Region Patch.
A HARP number identifies a tracked magnetic patch in the HMI/SHARP data system. It is not the same thing as a NOAA active-region number.
For this project, the useful mapping is:
NOAA AR 11158 -> HARP 377at the relevant 2011-02-15 epoch.
How it appears in a DRMS query
A SHARP CEA query uses the HARP number inside the first bracket:
hmi.sharp_cea_720s[377][2011.02.15_00:00:00_TAI]{Br,Bp,Bt}Here 377 is the HARP number. The segment list in braces says which FITS arrays to download.
SHARP versus HARP
- SHARP data product is the HMI data product or series.
- HARP is the tracked patch identifier used to index that series.
The database/product is SHARP; the record ID for the magnetic patch is HARP.
Practical trap
Do not put the NOAA number directly into the SHARP query. 11158 is the NOAA label, not the SHARP bracket index. For AR 11158, the bracket index used here is 377.
If only the NOAA region is known, first confirm the matching HARP number, then write the DRMS query. Mixing the two numbering schemes can download the wrong region or fail in a way that is annoyingly quiet.