What the markers mean
Click a marker to toggle it · use
Box Select /
Lasso Select in the map toolbar to pick many at once · faded markers
have no data period reaching the Start/Stop range (a non-faded one can still
have gaps inside it) and are
skipped by “Select in range” and
“All with data” — clicking one still selects it
· a green ring marks an observatory that already has a panel.
Orange diamonds are WDC Kyoto monitor stations, not observatories:
the data are unprocessed variations and carry several caveats — these
are shown on the panel once it is added, and in
the caution
on the landing page.
Magnetic latitude lines come from IGRF-14, computed offline with
the WDC Kyoto field routines.
Geomagnetic is the centred-dipole
latitude (the same quantity the
coordinate
transformation service returns) —
not AACGM or
quasi-dipole.
Dip latitude is arctan(tan I / 2) at sea level, so its
zero line is the dip equator. The epoch follows the Start/Stop range and is
written in the corner of the map; outside 1900–2030 the lines are
dashed because the model does not reach that far. The quantity selected
here is also the one the
Mag lat /
Dip lat fields under
“Select by a latitude / longitude … range” filter on, at
the same epoch;
Off hides the lines but keeps the last quantity for
the fields.
Select by a latitude / longitude or magnetic-latitude range
instead
Longitudes may be given as −180…180 or
0…360; Lon min > Lon max selects a range across the antimeridian.
The magnetic-latitude fields follow the Magnetic latitude selector
above: Geomagnetic (dipole) filters on the centred-dipole latitude
(not AACGM or quasi-dipole), Dip latitude on
arctan(tan I / 2). Both come from IGRF-14 at the epoch that
follows the Start/Stop range, and the range is drawn on the map as a red
dotted line. Off only hides the latitude lines — the fields
keep filtering on whichever quantity was chosen last. Ranges combine: a
station must satisfy every field you fill in.
