Heliophysics Event Knowledgebase (HEK) queries
This gives some examples of how to query the HEK. Note that
is described in Hurlburt et
al. (2012, Sol. Phys., 275, 67).
Constructing a query for isolsearch
For finding events, a good way is to first go to isolsearch and use the web-tool to find a feature (e.g., sunspots). Once your query is returned, look for the 'Search results' box and click on 'export'. Now click on 'Solarsoft Call' and you'll receive a line of IDL code that can be copied into an IDL session.
Note that the ssw_her_query routine returns a structure in which all tags are strings. Try giving the keyword '/struct' to convert, e.g., integer entries into integers.
Also note that a limit is applied to the number of results that are returned. This can be changed by specifying 'result_limit='.
Constructing a query from IDL
The query input to 'ssw_her_query' has a distinct format in which the query is a single string. To construct this query string from a more standard calling sequence do, e.g.,
Example 1: find IRIS observations of sunspots close to disk center
The IRIS catalog is built into the HEK so it's easy to
events against the IRIS catalog.
Here I search for IRIS observations close to sunspots during
period 22-oct-2013 to 23-oct-2013, with a restriction that the sunspots
are within +/- 300 arcsec of the central meridian.
There are 14 sunspots matched from the catalog (check the her.ss tag). Now we want to cross-match these against IRIS observations:
'rmatch' indicates that the IRIS pointing can be within 100" of the sunspot, and 'tmatch' that the IRIS observation can be within 1800s of the sunspot entry.
The routine hek_match_events always returns a null match (number of hits=1), so you have to look for when number of hits is more than 1. This is the case for her.ss.
Checking the output from hek_match_events, we find a match for a raster at 20:59 UT on 22-Oct-2013.
More generally, see the routine hek_find_iris_ss.pro for
finding IRIS sunspot observations for a specified month.
Example 2: find spatial location of GOES flares