Data of magnetic storms and term-day observations from the Prague-Clementinum observatory (1839-1849)@en

We provide in digital form unique data observed at Prague-Clementinum in years 1839-1849. The data were obtained by digitising and processing the original old records published in the yearbooks of this historical observatory. The data contain two categories of high cadence observations of magnetic declination and horizontal intensity. The first of these categories captures 73 magnetic storms with their magnitude being of at least a moderate level. The second category is the dense observations during the days that had been agreed for joint measurements by the observatories organised in the Göttingen Magnetic Union (GMU), these measurements being known as term-day observations. Whereas four terms per year were set by GMU, many observatories agreed to carry out additional observations in the eight remaining months. The term-day observations also continued being performed for several years after the end of the GMU activities in 1841. Data of 120 term-days from January 1840 to December 1849 are published. The observations started at 10 p.m. of Göttingen Mean Time and lasted 24 hours. The interval between observations was 5 minutes (in April, June and July 1842 exceptionally 6 minutes). All time data were transformed into UT, based on the longitude of the Göttingen observatory, which was 9.950°. The time shift is thus 39'48''. The date in the file name of magnetic storm indicates the start day of the event, whereas the date in the term-day file name indicates the second day which involves substantial part of the observations (22 out of 24 hours).本数据集以数字形式收录了1839年至1849年间于布拉格克莱门特天文台（Prague-Clementinum）获取的独有观测数据。该数据集通过对该历史观测台年鉴刊载的原始旧记录进行数字化加工与处理后得到。数据集包含两类高时间分辨率的磁偏角与水平强度观测数据：第一类涵盖73次强度等级不低于中等的磁暴事件；第二类为哥廷根磁学联盟（Göttingen Magnetic Union, GMU）旗下各观测台约定开展联合观测的时段内的密集观测数据，此类观测被称为观测日（term-day）观测。尽管GMU将每年划分为4个官方观测时段，但多数观测台同意在剩余8个月开展补充观测。观测日观测甚至在GMU于1841年终止活动后，仍延续开展了数年。本数据集收录了1840年1月至1849年12月期间共计120个观测日的相关数据。观测以哥廷根平均时间（Göttingen Mean Time）当日22时启动，持续时长为24小时。观测间隔为5分钟；1842年4月、6月及7月除外，此期间观测间隔调整为6分钟。所有时间数据均基于哥廷根观测台的经度（9.950°）转换为世界时（Universal Time, UT），对应的时间偏移量为39′48″。磁暴数据文件的文件名中的日期代表该事件的起始日期，而观测日数据文件的文件名中的日期则代表包含主要观测时段（24小时中的22小时）的次日。