20 research outputs found
Records of sunspot and aurora during CE 960-1279 in the Chinese chronicle of the Song dynasty
Records of sunspots and aurora observations in pre-telescopic historical
documents can provide useful information about solar activity in the past. This
is also true for extreme space weather events, as they may have been recorded
as large sunspots observed by the naked eye or as low-latitude auroras. In this
paper, we present the results of a comprehensive survey of records of sunspots
and auroras in the Songshi, a Chinese formal chronicle spanning the tenth to
the thirteenth century. This chronicle contains a record of continuous
observations with well-formatted reports conducted as a policy of the
government. A brief comparison of the frequency of observations of sunspots and
auroras and the observations of radioisotopes as an indicator of the solar
activity during corresponding periods is provided. This paper is the first step
of our project in which we survey and compile the records of sunspots and
aurora in historical documents from various locations and languages, ultimately
providing it to the science community as online data.Comment: Accepted for for publication in Earth, Planets and Space. This
manuscript includes the original texts in Chinese, which is omitted in the
version published in EP
A Great Space Weather Event in February 1730
Aims. Historical records provide evidence of extreme magnetic storms with
equatorward auroral extensions before the epoch of systematic magnetic
observations. One significant magnetic storm occurred on February 15, 1730. We
scale this magnetic storm with auroral extension and contextualise it based on
contemporary solar activity. Methods. We examined historical records in East
Asia and computed the magnetic latitude (MLAT) of observational sites to scale
magnetic storms. We also compared them with auroral records in Southern Europe.
We examined contemporary sunspot observations to reconstruct detailed solar
activity between 1729 and 1731. Results. We show 29 auroral records in East
Asian historical documents and 37 sunspot observations. Conclusions. These
records show that the auroral displays were visible at least down to 25.8{\deg}
MLAT throughout East Asia. In comparison with contemporary European records, we
show that the boundary of the auroral display closest to the equator surpassed
45.1{\deg} MLAT and possibly came down to 31.5{\deg} MLAT in its maximum phase,
with considerable brightness. Contemporary sunspot records show an active phase
in the first half of 1730 during the declining phase of the solar cycle. This
magnetic storm was at least as intense as the magnetic storm in 1989, but less
intense than the Carrington event.Comment: 30 pages, 5 figures, and 2 tables, accepted for publication in
Astronomy & Astrophysics on 25 April 2018. The figures and
transcriptions/translations of historical documents are partially omitted in
this manuscript due to the condition of reproduction. They are available in
the publisher versio