Abstract:
Magnetic variations show different records at each observatory. They depend mainly on the latitude of the observatory and the local time. This paper reports the definitive geomagnetic data obtained at Panagjurishte Observatory in 2018, prepared in the form of local geomagnetic indices and absolute time-series of daily mean values plots. 2018 is the penultimate year of Solar cycle 24, which is well into its decreasing phase (https://www.swpc.noaa.gov/products/solar-cycle-progression). It had a “double-peaked” solar maximum, with the first peak reaching a sunspot number of 99 in 2011 and the second peak in April 2014 with 101. On the 24th of May 2018 the observatory was struck by a severe lightning storm. This damaged both systems, and they were sent out for repair. In the aftermath of this event, the observatory lost its capability to record data until the beginning of August 2018. Calculated indices show that 2018 had 19 days with “storm”- level conditions of the geomagnetic field, but only moderate levels have been reached. The maximum K-index level reached during the period is K=6, recorded in four separate events. This weak activity is reasonable due to the fact that the sunspot numbers that year continued to decline. Verification of data quality is performed according to “IAGA guide for magnetic measurements and observatory practice” and due to the missing data this year is labeled as “incomplete”.