東京大学木曽観測所
超広視野高速CMOSカメラTomo-eの開発
Shigeyuki Sako (IoA, U Tokyo) and the Tomo-e Gozen project team: M. Doi, K. Motohara, T. Miyata, N. Kobayashi, T. Morokuma,ABSTRACT

東京大学木曽観測所では105cmシュミット望遠鏡の視野（φ9度）のすべてを84台の常温駆動CMOSイメージセンサで覆う超広視野高速カメラthe Tomo-e Gozen cameraの開発を進めている。Tomo-eは最大2Hzのフレームレートで計20平方度の視野を連続的に観測できる。読み出しを特定の領域に限ることで20Hz以上の高速観測も可能である。CMOSセンサを常温・常圧環境下で用いることで、カメラ筐体の軽量化と小型化を実現する。Tomo-eは他の装置に無い高時間分解能と超広視野高感度を合わせ持つため、10秒以下の短時間微光変動現象の探査を初めて可能にする。Tomo-eはプロトタイプ機を製作した後に、2017年度の完成を予定している。
これまでにCMOSセンサの性能評価を実施し、科学観測に使用できる水準に達していることを確認した。現在、Tomoeの各ユニットの詳細設計を進めている。

SPECIFICATION
Specification of the Camera

Field of View

ZTF (1.2m) , 47 deg2 (2016-)

KWFC/Kiso
4.8 deg2, CCD

Kiso Schmidt telescope
φ 9 deg

LSST (8.4m), 9.6 deg2 (2023-)

Sensors driven
at“ordinary temperature”
and“ordinary pressure”

Pan-STARRS (1.8m), 9 deg2

Overview ofTomo-ecommissioning in 2017

 Telescope: Total sky coverage:
 Sensor: Chips:
 Pixel scale : Data size: Frame rate : Data rate: Filter :Field of view of Tomo-e
20 deg2 in φ 9 deg
Mosaic CMOS sensors

Kiso 105 cm Schmidt
20 deg2 in φ 9 deg
1k x 2k CMOS sensor
84
1.2 arcsec/pix
760 MB/exposure
2 frames/sec (max)
27 TB/night (max)SDSS-g+r, SDSS-g, SDSS-r †† Manually exchanged in the daytime

SCIENCE CAPABILITY
Detection Capability for Transient Events

Scientific Strategies― key-words: Rare, Transient, and Sub-second Time-domain□ 1-hour-cadence all-sky monitoring

CCD• All sky (10,000 deg2), 1 hour cadence• Recording period: 3 years• Limiting mag.: Vmag ~18 (1 hour), ~19 (1 day)

ZTF

19192225 20

Tomo-eLSST

Pan-STARRPTF

20 2023 KWFC

125

The numbers in the circles
indicate limiting magnitudes.

Decam
HSCSDSS

22

10

10.1

-18

-22

-16-20-14-18-120

100-1600.5200
300
Days since bolometric peak (days)

1Shock breakouts of core-collapse supernovae(Detections of 5 events per year expected)□ 20-fps wide-field monitoring

Time resolution (sec)100- Tomo-e can open the new parameter space by
the high-speed and wide-field observations.

••••

2 deg2 (partially readout) in φ 9 deg
20 frame/sec, Continuous mon. of 10,000 stars
Recording period: 1 year
Limiting magnitude: Vmag ~ 14300 msec

Stellar occultations by TNOs
(Trans Neptune Objects)

2 deg2 in φ 9 deg,
20-fps, 10,000 stars

 Very bright, but Rare and Very Fast time-variables□ Synergy with high-energy astronomy• Optical wide-field follow-up• Trigger sources are Gravitational Wave, Neutrino, and Gamma-ray

Gravitational wave
detector KAGRA□ Near and interior Earth objects• Phenomena in background• During other surveys

 Faint meteors
 Fast moving NEOs

- Rate: a few dozen events/min- Brightness distribution of meteors- Moving speed: 10-100 arcmin/sec- Cannot detected by CCDs with ordinal FoVs

Log10 Cumulative Flux (particles m-2 s-1 2π str-1)

1018

All sky, 1 hour cadence
monitoring Bright, but Rare and Fast time-variables

Unexplored space

15

Estimated detection rate = 1/100 SNe
Absolute magnitude

CMOS

100
Field of View (deg2)

Extremely wide-field high-speed CMOS camera

the Tomo-e Gozen Camera

H. Takahashi, R. Osawa, T. Aoki, T. Soyano, K. Tarusawa, H. Maehara, H. Mito, Y. Nakada, S. Todo, Y. Kikuchi, (IoA, U Tokyo), F. Usui,
N. Matsunaga (DoA, U Tokyo), M. Tanaka, J. Watanabe (NAOJ), N. Tominaga (Konan U), Y. Sarugaku, K. Arimatsu (ISAS/JAXA), Y. Ita,
H. Onozato, T. Hanaue, H. Iwasaki (Tohoku U), S. Urakawa (Japan Spaceguard Association), H. Kawakita, S. Kondo (Kyoto Sangyo U)

Neutrino detector
Super-Kamiokannde

Gamma-ray telescope
SWIFT, Fermi, MAXI??

Hughes 1978Is the power law
extended to faintmeteors?

Log10 Particles Mass of Meteor (g)CMOS SENSOR
Specification of CMOS Sensor
40 arcminVmag

12’12’

2000 x 1128 pix

23’12’

35 mm full HD CMOS sensor

developed by Canon and U-Tokyo
based on products for commercial use.

Laboratory tests and Test observations
conducted in U-Tokyo (2012-2013)

Pixels2000 x 1128

Pixel size

19 μm

Architecture

Front side illuminated + micro lens array

Surface protection

Cover glass with AR coating

Output16 ch differential analog out

Internal amplifier

Integration time (sec)Vmag1/10

15.3

117.2

G = x1, x4, x16, x64, x256

1018.7

Frame rate

30 fps (max)Read out mode

Rolling read out

100

19.9

Power dissipation

1.8 W @30 fps

QE (Aη)0.45 @λpeak=500nm, 0.25 @λ=380, 700nm

Read out noise

2.3 e- rms @30 fps @G = x16

Dark current

0.05 e-/pix/sec @273 K

Saturation

55,000 e-/pix @G = x1
5,700 e-/pix @G = x16

Filling factor

Sensor area/Package area = 0.3

Package size

60.9 mm x 44.6 mm- Low dark current at room temperature- Low readout noise in fast frame rate
Tomo-e Gozen (Lady Tomo-e, 巴御前)
born in the Kiso region in the 12th century
and known with bravery.

See the poster presentation on a readout system for
the CMOS sensors by Kikuchi et al. in this workshop.

S/N = 5, Seeing = 3” wo/ readout dead time
Parameters used for the estimation
Background photons:
Readout noise:
Dark current at 273 K:

13 e-/s/pix
2.5 e0.05 e-/s/pix

Assuming w/ broad band on Kiso Schmidt indark sky (20 mag/arcsec2)

2120
Limiting magnitude

12’Estimated Limiting Magnitude

190.2 magdue todQE

18171615140.1110100
Integration time [sec/frame]- Higher sensitivity than CCD in tinteg < 10 sec.
- Higher exposure efficiency expected in continues
observations owing to zero readout time.

the Tomo-e Gozen Project, Kiso observatory, the University of Tokyo

第4回可視赤外線観測装置技術ワークショップ, 2014. 12. 3, 国立天文台三鷹