Stars and Galaxies, Vol. 04 (2021年)


A new simple method to observe Doppler shift of the meteor head echo using low-cost and low-power ham radio devices and free FFT software
Author:Kazuhiro Suzuki1 and Yasuo Katoh2
1) Seijoh High School, Sakae-cho, Toyoake, Aichi, 470-1161,, Japan
2) Toyohashi High School of Technology, Kusama-cho, Toyohashi, Aichi, 441-8141, Japan
Received 2021 October 30; Accepted 2021 November 20

A meteor is a phenomenon in which extraterrestrial material, generally known as a meteoroid, enters the Earth's atmosphere, ionizing the surrounding components and/or emitting light. The surface of a meteoroid moving at high speed reflects very high frequency (VHF) radio waves by melting itself and ionizing the compone nts of the surrounding atmosphere. The radio wave reflected from the head of a m eteor is called a meteor head echo and results in a Doppler shift.
Since the early 2000s, some researchers have made multi-static measurements of h ead echoes using high-power large-aperture pulse radars. Meanwhile, the authors have attempted to observe meteor head echoes with Doppler shifts using tradition al low-cost and low-power ham radio devices for over a year. Moreover, by settin g the transmitter and the receiver in close proximity, it became clear that the Doppler shift shows a value that follows the meteor velocity component in the li ne-of-sight direction. This implies that any observer who is involved in amateur radio operations can make observations similar to those obtained from a large-s cale pulse meteor radar.
Using this technique, the authors recorded two remarkable Eta Aquarids meteor h ead echoes in a location very close to the transmitting station, in May 2021. Th e Doppler shift calculated from the meteor head echo agreed well with the data o btained from the position of the meteor's actual path using the known physical p arameters of the Eta Aquarids meteors. We propose that this method facilitates t he observation of meteor head echoes at multiple points simultaneously, enabling the estimation of the position and ground velocity of a meteor. This system wil l help us find the path of a meteorite during daytime hours or on cloudy days.

 Key words:meteor head echo— Doppler shift: ham radio devices — Eta Aquarids meteor
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Development of scientific understanding of aurorae from the early modern to the modern Japan
著者:北井礼三郎1, 岩橋清美, 玉澤春史3, 磯部洋明3
1) 立命館大学、〒603-8577 京都市北区等持院北町56-1
2) 國學院大學、〒150-8440 東京都渋谷区東4丁目10-28
3) 京都市立芸術大学、〒610-1197 京都市西京区大枝沓掛町13-6
Author:Reizaburou Kitai1, Kiyomi Iwahashi2, Harufumi Tamazawa3, and Hiroaki Isobe3
1) Ritsumeikan University,56-1, Toujiinkita-cyou, Kitai-ku, Kyoto 603-8587, Japan
2) Kokugakuin University, 10-28 Higashi 4-cyoume, Shibuya-ku, Tokyo 150-8440, Japan
3) Kyoto City University of Arts, 13-6 Kutsukake-cho, Oe, Nishikyo-ku, Kyoto 610-1197, Japan
Received 2021 October 30; Accepted 2021 December 13

1872年2月4日に発生した低緯度オーロラが、岐阜県の飛騨高山でも観測され、「桐山如松 記」に天紅として記録されていた。1872年以前にも、低緯度オーロラは我が国では「赤気 」とよばれて記録されてきている。人々は天変であるとして様々な反応を示したが、その 科学的理解はされていなかった。オーロラ現象の科学的理解について、新聞記事上の変遷 、西欧の研究成果の日本への伝来時期、明治期の地球物理学会の論文の進展を調査し、明 治中期から明治末期にかけて、オーロラに対する科学的理解が進展したことを明らかにし た。

A low-latitude aurora on Feb 4, 1872 was observed and documented in a private di ary by a citizen ( Jyosyou Kiriyama ) in the central part of Japan. The document describes the observed temporal variation of the aurora and also the response o f the resident citizens to the unusual event in the night sky. There has not bee n any scientific understanding of aurorae common to the Japanese citizens until 1870’s. Following the change of description in newspaper articles, history of in flux of western knowledge on aurorae and the creation and development of academi c societies in Japan, we found that the Japanese scientific understanding of aur orae prevailed widely in early 1910’s.

 Key words:Aurora — Historical records — Scientific understanding
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New dome-flat system for 2m-Nayuta telescope
Authors:Masaki Takayama
Affiliation:Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407–2 Nishigaichi, Sayo-cho, Hyogo 679–5313, Japan
Received 2021 October 30; Accepted 2021 December 17

なゆた望遠鏡のドームフラットシステムを刷新した。 従来のスクリーン斜めからの一点照射に代わり、ランプを望遠鏡トップリングに設置した 4点正面照射へと改修した。
また西はりま天文台近赤外撮像装置NIC(Nishi-harima Infrared Camera)を用いて新しい ランプシステムの性能評価を行なった。 NICのJ bandを用い、新しいドームフラット・ポジションとして望遠鏡高度40度、 ドーム方位と望遠鏡方位の角度差71度が導出された。
続けて、トワイライトフラットが十分均一な光源であると仮定し、トワイライト画像との 比較からドームフラットの円周方向の一様性と、半径方向の一様性について調査した。 ドームフラット画像の円周方向にはJ、H、Ks band共に依然として輝度の偏 りが存在することが明らかになった。しかしながら3つのband全てで円周方向の輝度のば らつきによる標準偏差は、平均値の1 %以下であった。
またJとH bandではドームフラットの半径方向の輝度の偏りは検出できなかったが、 その標準偏差の上限値としてそれぞれ8.5 %と3.8 %を得た。一方Ks bandで はわずかに画像中心のカウントが高く、周縁部で低くなる傾向が見られた。カウントの平 均値に対する標準偏差は2.6 %であった。
旧ドームフラット画像では、トワイライトフラットに対する差異の標準偏差は$J$ bandで 14$\%$、$H$ bandで8.8$\%$、$K_{\rm s}$ bandで17$\%$であった(cf. 石黒 他 2011)。 したがって、新しいドームフラットは旧ドームフラットに比べ4割から一桁程度、輝度ム ラが小さくなった。

The dome-flat system for 2m-Nayuta telescope has been updated. In the previous system, one lamp irradiates the flat-screen diagonally. In the new system, four lamps on the top-ring of the telescope irradiate the screen head-on.
We examined the performance of the new lamp system by using NIC (Nish-harima Infrared Camera). Using the J band frames, the telescope elevation of 40 degree and the difference of azimuth angle between the enclosure and the telescope of 71 degree have been derived as the best position for taking the flat images.
The uniformity along the circumference and the radial direction in the flat imag es has been investigated by a comparison with the twilight flat images. There was still unevenness of the luminosity along the circumference of the J, H, and Ks band flat-images However, the standard deviations along the circumference of the flat images in all three bands were below 1 %.
We could not find unevenness of the luminosity along the radial direction of both J and H band flat-images. The estimated upper limit of the standard deviations in the J and H bands were 8.5 % and 3.8 %, respectively. On the other hand, there were higher values of count in the center of the flat-images in the Ks band and lower values of count in the rim. The standard deviations along the radial direction of the flat images in the Ks band was 2.6 %.
The unevenness of the intensity in the previous dome flat were 14 %, 8.8 %, and 17 % in the J, H, and Ks bands, respectively. Therefore the new flat system has achieved to decrease the unevenness of the intensity roughly a 40 percent or an order.

 Key words:Instruments — Dome flat — Nishi-harima Infrared Camera (NIC)
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A study of the luminosity variability of distant quasars by near-infrared imaging with Nayuta/NIC
著者:関根章太1, 井上昭雄1,2, 斎藤智樹3, 山中郷史4
1) 早稲田大学理工学術院先進理工学研究科物理学及応用物理学専攻, 169-8555, 東京都新宿区大久保3-4-1
2) 早稲田大学理工学術院総合研究所, 169-8555, 東京都新宿区大久保3-4-1
3) 兵庫県立大学 天文科学センター 西はりま天文台, 679-5313, 兵庫県佐用町西河内407-2
4) 鳥羽商船高等専門学校, 517-8501, 三重県鳥羽市池上町1-1
Author: Shota Sekine1, Akio K. Inoue1,2, Tomoki Saito3, Satoshi Yamanaka4
1) Department of Physics, School of Advanced Science and Engineering, Faculty of Scinece and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
2) Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan
3) Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Hyogo 679-5313, Japan
4) NIT Toba Collage, 1-1 Ikegami-cho, Toba-shi, Mie 517-8501, Japan
 Received 2021 November 1; Accepted 2021 December 18

遠方宇宙の明るい活動銀河核クェーサーの大質量ブラックホールの起源は大きな謎である. この問題を議論する一つの方法として,クェーサーの変光を観測することが考えられる. そこで私たちは,4つのクェーサー,PSO 183+05 (赤方偏移z = 6.44),PSO 338+29 ( 赤方偏移z = 6.66),ULAS J1120+0641 (赤方偏移z = 7.09),ULAS J1342+0928 ( 赤方偏移z = 7.54)について,なゆた望遠鏡NICを用いて,J, H, Ksの3バ ンド同時撮像を1週間〜2年間に渡って行なった. それぞれのターゲットの変光の有無について,文献値との比較も行い調査した. PSO 338+29とULAS J1342+0928のJバンドについて,〜2 sigma程度の変光の兆 候が見られた. 今後,継続して観測を行い変光が実際に起きているのか確認していく必要がある. また,変光調査の性質上,等級を正確に求めることが重要であり,慎重に検討を行なった. そのため本研究では,誤差をポアソン誤差,ゼロ点補正誤差,周辺星補正誤差の3つの成 分からなると考え,誤差を評価した. さらに2021年の観測では,誤差を改善するためディザリング点数を10点から7点に変えて 観測を行なった. ディザリング点数の変更による,測光誤差への影響は見られなかった. 他の誤差への影響は今後の検討課題である.

The origin of supermassive blackholes in quasars, distant Active Galactic Nuclei, is a great mystery. One possible way to address this problem is to observe the luminosity variability of quasars. In this paper, we present time variability analyses for four quasars, PSO 183+05 (redshift z = 6.44), PSO 338+29 (redshift z = 6.66), ULAS 1120+0641 (redshift z = 7.09) and ULAS 1342+0928 (redshift z = 7.54) based on near-infrared imaging observations with NIC (Nishiharima Infrared Camera) on the Nayuta Telescope over one week to two years. We have examined whether these targets have time variability in luminosity in ou r data and in literature. J band magnitude of PSO 338+29 and ULAS J1342+0928 show z ~ 2 sigma level possible signs of the variability. We need to continue to observe these quasars to confirm whether the variability is real. For the variability research, it is important to obtain magnitude accurately. In this paper, we have carefully examined the magnitude uncertainty which is considered to be composed of Poisson errors, zero-point errors, and systematic errors compared with stars around the targets. Furthermore, we carried out 7-point dithering observations during the 2021 run, instead of the default setting of 10-point dithering, in order to reduce the uncertainties. However, we could not see the reduction of the Poisson error by the change of dithering points. The effect on other errors is a subject for future study.

 Key words:quasars: supermassive black holes
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Development of Polarimetry Mode for WFGS2
所属:兵庫県立大学天文科学センター 西はりま天文台 〒679--5313 兵庫県佐用郡佐用町西川内 407-2
Authors:Aoi Kawakami, Yoichi Itoh, Jun Takahashi, Miyako Tozuka, Masaki Takayama
Affiliation:Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Hyogo 679-5313, Japan
Received 2021 November 16; Accepted 2021 December 25

我々は、兵庫県立大学西はりま天文台 広視野グリズム分光撮像装置(WFGS2)の偏光撮像 モードを開発した。半波長板ユニット、偏光分離素子、偏光観測用のアパーチャーマスク を取り付け、試験観測を行った。無偏光標準星の観測により、器械偏光度はBバンドで 1.33±0.10 %、Vバンドで0.63±0.04 %、Rcバンドで0.22±0.06 %と求められた。また、器械偏光の方位角は装置ローテータの回転角に依存して 変化することが分かった。さらに、強偏光標準星を観測し、偏光度・偏光方位角の精度を 検証した。Vバンドで16.8等の天体は、総積分時間3600秒で0.5 %の精度で偏光度を求 めることができる。

We developed the imaging polarimetry mode for the Nishiharima Astronomical Obser vatory Wide Field Grism Spectrograph 2 (WFGS2). A polarizing beam splitter, a ha lf-wave plate unit, and an aperture mask for polarimetry were equipped. By obser ving for unpolarized standard stars, the degrees of polarization of the instrume nt was determined to be 1.33±0.10 %, 0.63±0.04 %, and 0.22±0.06 % for the B-, V-, Rc-bands, respectively. The position angle s of the instrumental polarization depends on the rotation angle of the instrume ntal rotator. We also observed strongly polarized standard stars and estimated t he accuracy of polarization degrees and position angles. For an object with 16.8 mag in the V-band, the degree of polarization can be obtained with an accurac y of 0.5 % with a total integration time of 3600 seconds.

 Key words:instrumentation: polarimeters — techniques: polarimetric — polarization
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Distributions of dwarf galaxies around giant elliptical galaxies NGC 3923 and NGC 4636
Authors:Miyako Tozuka1, Koji S. Kawabata2, Yasushi Fukazawa2, Shingo Nishiura3, Junko S. Hiraga4
1) Nishi-Harima Astronomical Observatory, Center for Astronomy, University of Hyogo, 407-2 Nishigaichi, Sayo-cho, Hyogo 679-5313, Japan
2) Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima-shi, Hiroshima 739-8526, Japan
3) Tokyo gakugei University, 4-1-1 Nukuikita-machi, Koganei-shi, Tokyo 184-8501, Japan
4) Kwansei gakuinn University, 2-1 Gakuen, Sanda-shi, Hyogo 669-1337, Japan
Received 2021 October 14; Accepted 2021 December 27

To obtain more information on the environment around elliptical galaxies, we observed the properties of dwarf galaxies around two giant elliptical galaxies, NGC 4636 and NGC 3923, using optical wide-field deep imaging. These galaxies have similar optical luminosities but have widely varying X-ray luminosities. We applied a convolution technique to detect low surface brightness objects, such as dwarf galaxies and used detection algorithms to identify groups of connected pixels exceeding a predetermined threshold above the background level. The well-observed radial profiles around NGC 4636 reveal that its dwarf galaxies are highly concentrated, especially its red dwarf galaxies. Although both NGC 4636 and NGC 3923 are similarly massive elliptical galaxies (M > 10^11 Mo), based on gravitational mass profiles, NGC 4636 has a larger-scale potential structure than NGC 3923, with its dark matter surroundings becoming dominant. At a large distance of 300 kpc, NGC 4636 seems to have a d eeper dark matter halo than NGC 3923, with a slightly higher number density of dwarf galaxies. In this work, our analyses obtained complete optical number density of dwarf galaxies around elliptical galaxies down to an absolute magnitude of MV = -15.5 within 300 kpc, which is the region of dark matter dominance. Given that elliptical galaxies typically have an absolute magnitude of around MV = -22 mag, the faint end corresponded to a stellar mass ~ 1/1000 that of a giant elliptical galaxy, with a typical mass of ~ 10^8Mo. The number density of galaxies at MV = -15.5 is 112.2 ± 65.21 Mpc^-2 around the X-ray-bright NGC 4636 and 38.7 ± 36.15 Mpc^-2 around the X-ray-faint NGC 3923. These values are lower than that of rich clusters of galaxies but higher than th at of our local galaxy group that includes M31.

 Key words:elliptical galaxies; dwarf galaxies; number density
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