otsubo のすべての投稿

UK Branch Open

Our laboratory now opens a branch in Great Britain!  We have just finished the first “remote” (Herstmonceux-Kunitachi) seminar this morning/evening.

大坪は今週よりイギリスに来ています.本日,Herstmonceux と国立をつないで,学部学生と第1回のリモート (HangOuts) ゼミを行ったところです.時差が8時間あるので,時間を合わせるのがたいへんです.


3D-printed Laser Reflector Array

A laser retroreflector array is 3D-printed and assembled! This is a 65% scale model of SALAL’s LRA (ILRS Website).  It consists of a body, 9 retroreflectors and 9 hoods.  Created by Nakanishi-san.
大学院生の中西さんが,たいへん苦労してきめ細かく再現してくれました.おつかれさま! 研究室のソファーのあたりに展示しています.

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講演完了報告: JPGU 2016 幕張

JPGU 2016 の5月23日午前 測地学一般・GGOS セッション にて,本研究室から次の2件の口頭発表を行いました.

  • 「経験的加速度の時間変化で探る衛星の摂動」 服部 晃久, 大坪 俊通
  • 「衛星レーザ測距観測網の拡充: 新たな局はどこに?」 大坪 俊通, 松尾 功二, 山本 圭香, 青山 雄一, ホビガー トーマス, 関戸 衛, 久保岡 俊宏




講演予定: JPGU 2016 幕張

2016-05-23 幕張メッセ
JPGU Meeting 2016

「経験的加速度の時間変化で探る衛星の摂動」 服部 晃久, 大坪 俊通

「GGOS 時代に向けた宇宙測地解析戦略」 大坪 俊通, 松尾 功二, 山本 圭香, 青山 雄一, ホビガー トーマス, 関戸 衛, 久保岡 俊宏

SLR Hit Rate 2015

An 2015 update of SLR performance assessment. The methodology was reported at the 17th International Workshop on Laser Ranging (Slide PDF) in 2011.


We have worked up some interesting statistics about the ratio of successful ranging observations with respect to all possible observations (> 20 degrees of elevation).  Let us call it “hit rate” here – this is somehow similar to a batting average of a baseball (not a cricket) player.  In other words, it is equal to the probability that a satellite flying over a station is laser-ranged from the station.  Sky conditions are not taken into account.

The most productive 20 stations (ILRS Global Performance 2015 4Q) in 2015 are tested here. We show the results for four satellite groups: (1) “ETALON-1 and -2”, (2) “LAGEOS-1 and -2”, (3) “LARES”, (4) “STARLETTE and STELLA”. Fig. 1 shows the pass-based hit rate and the NP-based hit rate.

Fig 1 (click to enlarge). Pass-based hit rate and Normal-point(NP)-based hit rate.

As we see the ratio between the pass-based hit rate (black) and the NP-based hit rate (grey) differs by stations, the average number of NPs per pass is now plotted in Fig. 2. Note that this is the average among observed passes.

Fig. 2 (click to enlarge). Average number of normal points per pass.

It is recommended to track a wide coverage from horizon to horizon, even if it is sometimes interrupted. The average duration of a pass is therefore plotted in Fig. 3.

Fig. 3 (click to enlarge). Average pass duration, defined as the time between the 1st and the last NP

FY2016 = Sabbatical year


Otsubo takes a sabbatical year during Apr 2016 – Mar 2017, which means only a few seminar courses are offered at Hitotsubashi University.  He is appointed as a guest professor of the National Astronomical Observatory, and plans to stay in Europe this year.

Photo: 2016-04-01 MKP4010157_R