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.

hitrate15a
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.

hitrate15b
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.

hitrate15c
Fig. 3 (click to enlarge). Average pass duration, defined as the time between the 1st and the last NP

FY2016 = Sabbatical year

入学・進学おめでとうございます.平成28年度=2016年度,大坪は着任10年目にして研修年をいただくことになりまして,学部ゼミナール(4年のみ)と大学院ゼミナールを除いて,一橋大学で担当する講義はありません.一方で,国立天文台の客員教授に就きました(国立天文台客員教授等).研究推進のため海外(欧州)研修も計画中です.

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