The aim of this paper is to demonstrate the capabilities of a new automated analysis scheme developed for meteor head echo observations by the Shigaraki middle and upper atmosphere (MU) radar in Japan (N, E). Our analysis procedure computes meteoroid range, velocity and deceleration as functions of time with unprecedented accuracy and precision. This is crucial for estimations of meteoroid mass and orbital parameters, as well as investigations into meteoroid–atmosphere interaction processes. We collected an extensive set of data (>500 h) between 2009 June and 2010 December. Here, we present initial results from data taken in 2009 October 19–21. More than 600 of about 10 000 head echoes recorded during 33 h were associated with the 1P/Halley dust of the Orionid meteor shower. These meteors constitute a very clear enhancement of meteor radiants centred around right ascension α= and declination δ=. Their estimated atmospheric entry velocity of 66.9 km s−1 is in good agreement with 1P/Halley dust ejected in the year 1266 bc, which, according to simulations, crossed Earth’s orbit at the time of our observation. The Orionid activity within the MU radar beam reached about 50 h−1 during radiant culmination. The flux of sporadic meteors in the MU radar data, coming primarily from the direction of the Earth’s apex, peaked at about 700 h−1 during the same observations.

The aim of this paper is to give an overview of the monthly meteor head echo observations (528.8 h) conducted between 2009 June and 2010 December using the Shigaraki Middle and Upper atmosphere radar in Japan (34°.85 N, 136°.10 E). We present diurnal detection rates and radiant density plots from 18 separate observational campaigns, each lasting for at least one diurnal cycle. Our data comprise more than 106 000 meteors. All six recognized apparent sporadic meteor sources are discernable and their average orbital distributions are presented in terms of geocentric velocity, semimajor axis, inclination and eccentricity. The north and south apex have radiant densities an order of magnitude higher than other apparent source regions. The diurnal detection rates show clear seasonal dependence. The main cause of the seasonal variation is the tilt of the Earth's axis, causing the elevation of the Earth's apex above the local horizon to change as the Earth revolves around the Sun. Yet, the meteor rate variation is not symmetric with respect to the equinoxes. When comparing the radiant density at different times of the year, and thus at different solar longitudes along the Earth's orbit, we have found that the north and south apex source regions fluctuate in strength.

People have probably been watching the sky since the beginning of human history. Observers in pre-telescopic ages recorded anomalous events and these astronomical records in the historical documents provide uniquely valuable information for modern scientists. Records with drawings are particularly useful, as the verbal expressions recorded by pre-telescopic observers, who did not know the physical nature of the phenomena, are often ambiguous. However, drawings for specific datable events in the historical documents are much fewer than the verbal records. Therefore, in this paper, we show the possible earliest drawings of datable auroras and a two-tail comet in a manuscript of the Chronicle of Zūqnīn, a Syriac chronicle up to 775/776 CE to interpret their nature. They provide not only the historical facts in the realm around Amida but also information about low-latitude aurora observations due to extreme space weather events and the existence of sun-grazing comets.

On 2011 October 8, the Earth passed through a stream of dust ejected by the comet 21P/Giacobini–Zinner during its perihelion passage of the year 1900, causing an outburst of October Draconid meteors. 13 Draconids were observed among ∼6300 meteor head echoes with precisely determined orbits during an observational campaign ranging from October 8 05:00 ut to October 9 13:00 ut with the Shigaraki middle and upper atmosphere (MU) radar in Japan (34°.85 N and 136°.10 E). The meteor outburst occurred while the Draconid radiant was descending below and 2 h later rising up above the horizon. Therefore, 11 of the detections were from very low (<15°) elevation. The detection altitudes of the Draconids were high compared to sporadic meteors of the same velocity and radiant elevation. The weighted mean geocentric velocity of the 13 Draconids was 20.6 ± 0.4 km s−1, and the weighted mean radiant located at right ascension α = 263°.3 ± 0°.6 and declination δ = 55°.8 ± 0°.2.

During a great magnetic storm on Feb 11, 1958, a fan-shaped aurora was photographed at Memambetsu, Hokkaido, Japan – the first and oldest photograph record of auroras observed in Japan, accompanied by many hand-made drawings, thus, portraying a rare opportunity of coexistence between photograph images and hand-made drawings. In fact, the same portrayal reminds us of the great red aurora with fan-shaped white pillars observed during the 1872 and 1770 great magnetic storms. The hand-made sketches, photographs, and the spectral data revealed that the white pillars and red glow of the fan-shaped aurora were dominated by auroral green and red lines, respectively. From the analysis of newly digitized microfilm data and hand-made drawings, we found that the fan-shaped aurora appeared during the peak activity of magnetic storm and moved westward at 0.4 km/s at 400-km altitude at 38°–40° magnetic latitudes, which is consistent with the enhanced convection pattern in the middle latitude at storm time. Such a fan-shaped aurora can fundamentally characterize the middle-latitude evening-to-midnight auroras during great magnetic storms, which show the most destabilized transient appearance of the inner magnetosphere.