  In September 1859 the Colaba observatory measured the most extreme
geomagnetic disturbance ever recorded at low latitudes related to solar
activity: the Carrington storm. This paper describes a geomagnetic disturbance
case with a profile extraordinarily similar to the disturbance of the
Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic
observatory in Hungary. The analysis of the H-field at different locations
during the "Carrington-like" event leads to a re-interpretation of the 1859
event. The major conclusions of the paper are the following: (a) the global Dst
or SYM-H, as indices based on averaging, missed the largest geomagnetic
disturbance in the 29 October 2003 event and might have missed the 1859
disturbance, since the large spike in the horizontal component (H) of
terrestrial magnetic field depends strongly on magnetic local time (MLT); (b)
the main cause of the large drop in H recorded at Colaba during the Carrington
storm was not the ring current but field-aligned currents (FACs), and (c) the
very local signatures of the H-spike imply that a Carrington-like event can
occur more often than expected.
