The Tomo‐e Gozen project
Shigeyuki Sako (Institute of Astronomy, the University of Tokyo)

ICRR seminar, the University of Tokyo, 2019/2/27 15:30‐

Institute of Astronomy, the University of Tokyo
Kiso observatory
Kiso, Nagano, Japan
1.0‐m wide‐field Schmidt telescope

Headquarter
Mitaka, Tokyo, JapanThe university of Tokyo Atacama observatory (TAO)
5,600‐m alt., Atacama, Chile
1.0‐m mini‐TAO telescope
6.5‐m telescope (under construction)

Kiso Observatory
 Kiso observatory, Institute of Astronomy,
the University of Tokyo

Kiso

Correcting lens•••Established in 1974
Dark sky, 1120‐m altitude
Accommodation, Cafeteria

Mitaka Headquarters
Institute of Astronomy

Focal plane

Primary mirror

 Extremely wide‐field Schmidt telescope
•
•
•
•
•

Field of view:φ 9 degrees
Primary:
150 cm spherical mirror
Corrector :105 cm aperture
Focal ratio :3.1
Main instrument : Tomo‐e Gozen camera

OUTLINE
1. Introduction of Tomo‐e Gozen
2. Instrument and computing system
3. Survey plans and early results

5Snapshot of the Sky
Supernovae

Asteroids

6

LSST Project/NSF/AURA

1. Introduction

Time domain astronomy
The phase space of optical transients
gray: before PTF (‐2009)
points: new categories
discovered by PTF

[sec]
0.1

1

10

100

1,000

Fast Radio Bursts (radio flux)

Gamma‐rayburstsType Ia
Shock
breakout

Kilonovae

Soft gamma‐ray
repeaters• Exoplanet• Occultation bysmall bodies• Meteor• Magnetar• Pulsar• Black hole binary

Flare starts

Cooke (http://www.astro.caltech.edu/~ycao/B&ETalks/B&E_FRBs_Cooke.pdf)

10‐4

10‐2 10‐3

10‐1

100

101

Characteristic Timescale [day]8

Un‐novae

102
Peter Nugent, 13 February 2015, SPIE Newsroom

The Universe with HOURS time scale is less surveyed.
The Universe with SECONDS time scale is still unknown.

1. Introduction

Multi‐messenger astronomy‐ Gravitational waves were detected from a black hole‐black hole merger in 2015.
‐ The new astronomy with EM and non‐EM radiations has begun .

GW events detected by LIGO/Virgo

Neutrino cascade events detected by IceCube

LIGO

LIGO/Virgo/NASA/Leo Singer

Typical localization error is 10 – 100 deg2

IceCubeAartsen et al. 2017

Typical localization error is 10 – 100 deg2

QUICK optical follow‐ups with a few 10 DEG2 are required.
91. Introduction

Missing events in astronomy‐ Most of fast‐moving‐objects and flash‐events have been missed in surveys.

Meteors

Near earth asteroids

Unknown high‐energy flashes

Space debris© Jay Wong/All About Space magazine

Unknown alien planets

High‐speed and wide‐field observations with are required.
10

Wide‐field high‐speed camera
The Tomo‐e Gozen

Kiso Schmidt telescope
The University of Tokyo
D=105‐cm, f/3.1
11

The Tomo‐e Gozen
is named after
Tomo‐e Gozen(Lady Tomo‐e), who
is a woman warrior
born in the Kiso
region, Japan in the
12th century.

the Tomo‐e Gozen with 84 CMOS sensors
FoV of 20 deg2
Image: TNM Image Archives

Q1

Q2
Q4

Sako et al. 2018, SPIE, Kojima et al. 2018, SPIE,
Sako et al. 2016, SPIE, Morii et al. 2016, ApJ, Osawa et al. 2016, SPIE

Q3

the first wide‐field CMOS camera

The Tomo‐e Gozen• FoV of 20 deg2 in φ 9 deg• 84 chips of CMOS, 1k x 2k pixels• Consecutive frames at 2 fps (max)• Big movie data of 30 TB/night (max)• Room temperature, Non‐vacuum121. Introduction

CCD vs CMOS sensor

CCD

Charge coupled device
photon  e‐conversion

charge transfer

e‐  voltage
conversion

CMOS
photon  e‐conversion

Commercial video formate‐  voltage
conversion

switching◎ Large format (< 6k x 6k)◎ Large format (< 8k x 8k for commercial use)

△ Slow readout (>10sec)◎ Fast readout (>0.1sec)

global shutter only

Rolling shutter available〇 Simple structure◎ Embedded functional circuits  Low read noise△ High voltages necessary〇 Low voltages & low power◎ Backside and full‐depletion△ Backside and full‐depletion (hybrid structure)technologies establishedtechnologies under development

1. Introduction

Image taken on Nov. 201814

Counterweight

Q1 w/21 sensors

Q3 w/21 sensors

Counterweight

The full‐spec Tomo‐e Gozen will be completed in April 2019

Comparison of Field‐of‐Views
31’

1. Introduction

25.0’

39.7’ x 22.4’
ZTF (1.2m) , 47 deg2 , 2018‐,AΩ = 40 , Δτ ~ days, CCD
31’

Pan‐STARRS (1.8m), 9 deg2,AΩ = 15 , Δτ ~ days, CCD
25.0’

LSST (8.4m), 9.6 deg2 , 2023‐,
AΩ = 320 , Δτ ~ hours, CCD

Tomo‐e Gozen
20 deg2 in φ 9 degAΩ = 28, Δτ ~ subsec
CMOS sensors
15

FoV of KISO 1‐m Schmidt telescope1. Introduction

Survey power for transient events
CMOS

Field of View (deg2)

100

CCD

Tomo‐e Gozen

19 ZTF
19

17

10

25
22
16

unexplored universe

LSST
PanSTARRS

20

23
18

0.1

1

Decam
HSC

25 22 SDSSTAOS II

1

iPTF

10

100

Temporal resolution (sec)16

The numbers in the circles show limiting magnitudes.

Intensive Science Programs

1. Introduction

1. Transient survey‐ Elv > 40 deg (7,000 deg2 ) every 2 hours‐ 3 visits per night‐ Record all events < 20 mag (dark clear night)‐ SNs, Novae, variables

2. Follow‐up / Simultaneous‐ GWs, neutrinos‐ FRBs, NSs, BBHS, meteors, NEO,

Simulation of transient survey‐ Each circle: FoV with Φ9 deg‐ Yellow: Milky way

3. Fixed FoV + high‐speed‐ 2‐fps@ 20 deg2 ‐‐ 200‐fps@ 52” x 38”‐ Occultation of TNOs, YSOs, flares, FRBs, NSs, BBHs, meteors, NEOs17

1. Introduction

Organization
Kiso Observatory
Institute of Astronomy, the University of Tokyo
Director: N. Kobayashi

Tomo‐e Gozen Project
P.I.: S. Sako

Technical Working Group†

Science Working Group†

S. Sako (reader) and 36 persons

T. Morokuma, R. Ohsawa (readers)

based on collaborative researches, and KAKENHI

Supernova
Gravitational wave
Planetary system
Compact object
AGN
Star

Kiso Schmidt symposium on July 10‐11 2018

Data science18† Ini ally, the survey data can be accessed by only Tomo‐e members.

Camera development team

1. Introduction• Core members: ~10 persons• U‐Tokyo Mitaka staff + Kiso Observatory staff + Graduated students• 3 Master's thesis on camera development

19

7.5

OUTLINE
1. Introduction
2. Instrument and computing system
3. Survey plans and early results

20Requirements for high‐speed andwide‐field optical observations
0. Concept

2. Instrument• Simple is stable and sustainable.
• High‐speed frame read without dead time

1. Image sensor• Low read noise• Low power dissipation or cooler• Consecutive data acquisition

2. Data acquisition• High absolute time accuracy• High time stability

3. Optics• Wide field

4. Computing• Large storage, high‐speed processing & network, data visualization

5. Operation

21• Quick telescope system• Quick communication system for observers

Design concept of Tomo‐e camera

2. Instrument

 Discovery of transients
 Wide‐field and high‐speed
 Simple design‐‐‐

Tomo‐e Gozen Q1

ordinary temperature and pressure
w/o moving parts
easy maintenance All of raw data is deleted in 7 days.
21 chips of CMOS sensors of Q1
22

2. Instrument

Overview of Camera System
Q1
Q1

Q2

Q4
Q3
Back side view

Front side view
515 x 575 x t 540 mm

Q1 unit on the focal plane interface
Transparent glasses (default)

21 chips of CMOS sensors
Camera base
Bottom part
Small camera rack

HAPs

Top cover

Window frame‐ 12‐kg per camera
Large camera rack23

‐ 57‐kg in total

2. Instrument

Large pixel CMOS sensor

Kojima et al. 2018, SPIE

‐ Canon 35MMFHDXM‐ 2,000 x 1,128 pixels, front side illuminated‐ 19 m pix‐1‐‐‐‐

Micro lens array + cover glass
Rolling shutter
Photosensitive / package = 0.35
Analogue 16‐ch outputs
Photoelectric conversion efficiency
0.68 at a peak of 500 nm
efficiency‐ Photon sensitive: 370 – 730 nm‐ Power consumption: 230 mW chip‐1 @2‐fps‐ Well: 6,000 e‐, 53,000 e‐ @ G=x16, x1.7
‐ Read noise: 2.0 e‐, 9.2 e‐ @ G=x16, x1.7

‐ Dark current: 6 e‐ sec‐1 @305K
Wavelength (nm) Less than sky background in dark night, 50 e‐ sec‐1, at room temperature24

2. Instrument

Limiting magnitude

Duration time of flash (sec)5‐ limiting magnitude22

26 100

20

24
22

18

CCD

1

t

0.1

0.01

10

100

8.2m
1.8m
1.2m

20

CMOS

16

10

count

flash

1.0m

18
16

14

14
12

12

10

0.01

0.1

1

10

Exposure time (sec)
CMOS :CCD :efficiency=0.65, Nread=2 e‐efficiency=0.90, Nread=5 e‐

100

10

0.01

0.1

1

1000

Apparent moving speed (arcsec/sec)Tomo‐e Gozen :PanSTARRS, ZTF :LSST :

0.5 sec/frame, Nread=2 e‐
30 sec/frame, Nread=5 e‐
60 sec/frame, Nread=10 e‐assuming same filter‐bandwidth and pixel size
25

Kojima et al. 2018, SPIE

2. Instrument

Opticsf/3.1
Transparent glasses

Spherical focal plane of r = 3,300 mm
Required alignment accuracies: dz = 60 m, d = 0.1 degree
4.5 degree
beam

Ray trace diagram• Pixel scale: 1. 189 “ pix‐1 (typ. seeing 3”)

centerbeam• FoV of sensor: 39.7’ x 22.4’
correcting lens 1.0 m

FoVs of sensors
Scan directionof readout

Fraction of unvignetting rays

N
W

Q1

1.0

2 deg

0.8
25’.6
31’.0

FoV center of telescope

26

31’.0

25’.0

(1,1) of FITS

primary .5 m

0.6
0.4
0.2
0

0
center

0.9

1.8

2.7

Field (deg）

3.6

4.5
edge

2. Instrument

Photometry• Photometry with many reference sources• Quick follow‐ups for rapid variables
Movie obtained in 2‐fps,
consecutive 6 frames every pointing

Raw data

Diff data

1 chip, FoV of 39.7’ x 22.4’•

5‐ limiting mag: 18.7 mag•

Photometric accuracy: ~10 millimag @ time scale < 5 sec

27

20
10

20

10

t (min)20

relative
photometry

Relative counts•

Relative counts

1 fps

20
10

2

0

10

t (min)20

2. Instrument

DAQ and GPS system

GPS antenna
Telescope rack
Server roomin the dome

Camera units

optical fibers of 50‐m length

to mainbuilding
10‐Gbps LAN

Analogue DAQ

LVDS‐optical convertor, PCIe bus extension I/O
Sensor control signals
GPS trigger @1st pixel readGPS receiveru‐box EVK‐M8N

ZZ0‐046A‐ 1,344 ch of 16‐bit ADC, 400 ksps

‐ 24 boards, 32 bits, 10 MHz, bus‐master DMA‐ UTC time‐ 9.9 Mbyte/sec/chip at 2‐fps‐ Consecutive data acquisition‐ Absolute accuracy: 0.2 msec

‐ Synchronized with each other camera

28‐ High‐stability synchronization clock, ~10‐5

2. Instrument

On‐site computing system
Cameraunits

Weather monitoring system

Telescope rack

digital I/O +ServersGPS
antenna

LVDS – opt convertor‐ Abs. accuracy:
optical fibers of 50‐m

0.2 msec‐ Freq. stability:~10‐5• Camera controllers• Buffer servers

Telescope dome

• Analysis servers

2F control room•

Telescope controller

1F server room

• Storage servers

Status visualization systemCPU
72 cores
Memory 640 GB
HDD
40 TB
CPU
24 cores
Memory 256 GB
HDD
384 TB
90 cores
CPU
Memory 1024 GB
96 TB
HDD
CPU
12 cores
Memory 128 GB
HDD
384 TB

1 Gbps,Main building
10 Gbps, fiber connection

29

Remote operation
systemvia VPN + VNC

FLETs, NTTData visualization

2. Instrument

Tomo‐e Gozen Sky map

30

2. Instrument

Operation

Weather monitoring system• Automatic observations based on Queue system• Remote observations from Mitaka headquarters when needed.
• Quick information sharing

https://slack.com• LINE‐like app optimized for business• Many species of apps and bots.
• Easy and quick communication with multimedia.
31Volatile data management system
Off‐site

On‐site (10 Gbps network)
Information

Knowledge

AI

AI

Volatile

Every events(every 1min)

miningfor Science teams

Coord.
grid
Image
Coadd

GW
Supernova~1% of RAW~1% of RAW

Tomo‐e Gozen

External
sever

Astronomical data
centerin NAOJ

WWW
server& DB

Data archive &web server

Photo

Data

BufferserverSpark‐joy
ときめき

30 TB/nightminingTransient
Reduction
detection
server

~1% of RAW

Imagetrimming~1% of RAW

Moving obj.
detection~1% of RAW

Compressi
on~1% of RAW

Reduction servers~84 CPUsLong‐
Long‐term
term
storagestoragedata

DB servers~300 TB

High‐energy
transient

Young stellar
objects

Solar system&
Space debris

Transported
every 1‐monthKiso, Nagano
Mitaka, Tokyo
1 Gbps, commercial line (effectively 150 Mbps upload)32

2. Instrument

2. Instrument

Data Analysis

30 TB/night

Informatics method

Raw frame data

Machine learning, Sparse modeling,
Movie recognition, Data compression

On‐the‐fly analysis

Text table
Real‐time
Light curves of
105 objects

33

AI

AI

AI

Photometry of sources
detected in all frames

Buffer server

Detection of
Co‐addedshort timescale transient consecutive frames
Masked 3D‐FITS
Real‐time
unknownAI

Detection of very‐
fast‐moving objects
2D‐FITS

2D‐FITS
Real‐time
105 frames

105 frames

Day‐time

Monitor:

200 GB

250 GB

75 GB

500 GB (2x2 bin)

Survey:

30 GB

40 GB

500 GB

150 GB (2x2 bin)

2. Instrument

Informatics approach•#12

Machine learning• Random forest classifier• 3380 sets of training data including artificial data as NEOs
• False positive rate ~ 1%
• True positive rate ~ 99%

Detection#1
Frame data including
simulated NEO

Test• Un‐cataloged fast‐moving‐objects of~500 events/night are being detected.

~3,000 records

Training

Feature extraction
and labelingNEO candidates

Classifier#12 – #1 (6 sec apart)subtracted image

othersKojima et al 2018, ASJ meeting- Decomposed to Low-rank
and Sparse matrixes with
GoDec method.
Morii et al 2017, AJ

Nx
Ny

Time

Original matrix

Time

repeatplaybackTime
Pixel ID (Nx x Ny)- Expressed movie frames asa matrix.

34

Original (galaxy + flash)Sparse modeling

Image pixel•

Low‐rank

Low-rank(galaxy)SparseSearch for transient
events in Sparse matrix.

Compressed to~10% size

Sparse(flash)2. Instrument

Cyber space of Tomo‐e Gozen

Knowledge
Information
35

7.5

OUTLINE
1. Introduction
2. Instrument and computing system
3. Survey plans and early results

36All sources can be followedby spectroscopy with 1 – 3 mclass telescope

Tomo‐e transient survey
First wide‐field movie survey

10,000 deg2 ‐ 2 hr cadence ‐ 18 mag depth• no filter: effectively g+r (λ = 400 – 700 nm)• [0.5 sec exposure] x 12 frames• 6 sec exposure/visit• ~10,000 deg2 sky (El > 35 deg)
• 3 – 5 times visits per night

0.5 sec#12#1Targets

total 6 sec exp.

Supernovae, nova, pulsar, (GW), neutrino, comet, asteroid, meteor, occultation,
NEO, debri, super‐flare, dwarf star flare, CV, “Tomo‐e Flash” , YSO, Ultra‐Long
GRB, Fast Radio Burst, AGN, X‐ray transient, unknown unknown.
37

3. Survey

Tomo‐e transient survey
N

Tests with Q1 unit

38‐

2,000 deg2 survey in 2 hours‐

at each pointing• 0.5 sec exposure x 12 frames• 2 x 2 dithering‐

100 beam switches• moving time 6‐8 sec‐

Limiting magnitude of 5‐ 18 mag
is achieved.

Jan. 8th 2019E

W

S
Each circle is a FoV of full Tomo‐e, φ 9 deg

Detection pipeline fortransient sources

Tomo‐e transient survey

Detection for `hours timescale’ events
Tomo‐e raw‐movie data

total 6 sec exp.
image

#12
#1

Basic image
calibration

Differential
image

+
‐

stacked
0.5 sec each

Pan‐STARRS image (PS1,r‐band)
Simple photometry

108 records/nightin a few minutes

Web
interface

Tomo‐e transient
serversupernova

SQL
interface

stars
・・・

Alerts offollow‐ups

AGN

solar
systemClassifier based on
existing catalogues

candidates

Classifier based onmachine learning

AI
Bogus (artificial, seeing
dance, cosmic ray, etc.)
is rejected.

Multi‐wavelength catalogues including
AGNs, transients, and solar system.
( optical, UV, IR: SDSS, PS1, GALEX, WISE, AKARI…; X‐ray:
ROSAT, XMM‐Newton, Chandra…; radio: FIRST, NVSS, TGSS;SDSS(BAL) quasars, TNS transient, MPChecker… )Photometry tablewith feature values

Tomo‐eTomo‐e transienttransient survey
surveyDetection pipeline fortransient sources

Web and SQL interfaces forTomo‐e transient server
Initially, the data base is accessed only
via VPN connection of Kiso observatory.
In near future, it will be accessed with an
external rental server, but amount of
information is limited because of poor
network bandwidth, 150 Mbps upload
from Kiso.
You are welcome to contribute
improvement of network infrastructure!

3. Survey

Tomo‐e transient survey
Hounsell+2010

Classical novae

10 hr

Brightness at pre‐maximum halt
corresponds to Eddington
luminosity?  use as standard
candle.

Hours timescale events

X‐ray flaresBlack hole binaries
appears opticaltransient bursts.

MAXI X‐ray detector
on ISSBlack hole

5 daysMaehara+MAXI team+YSO flares, dust obscuration

Exoplanet surrounding WD?

OpticalInfrared

Rapid variabilities are observed
due to gas accretion and dust
disk in YSO system.
Mori+

Mon567
Stauffer+2014

Asteroid collisions

Broken by tidal disruption?
Minutes timescalevariability is detected.
WD 1145+017
Gänsicke +2016

1 day

Ohsawa+P/2010 A2

Comet outbursts
Fresh material isemerged frominside in outbursts.

Search for evidences ofa recent collision
between two asteroids.
Ishiguro+Super giant

NASA

Sarugaku+

1 hourCfA

Ishiguro+2013
17P/Holmes

3. Survey

Tomo‐e transient survey

P.I. Tomoki Morokuma (U‐Tokyo)
SN follow‐up collaborators~1,000 supernovae including ~ 5 earlyphases could be discovered per year.
• Very Early Phases of Core‐Collapse Supernovae• Very Early Phases of Type Ia Supernovae

Other three candidates discovered so far.

Single degenerate (SD) vs double degenerate (DD)42Light curve oftheoretical models

Jiang+2017, Nature, @z=0.117

Detection pipeline forfast‐moving sources

Tomo‐e transient survey

Detection for `v > 1 arcsec/sec’ sources
Masked frames with
only moving objects

Tomo‐e raw‐movie data

Masking stable sources+

0.5 sec each

‐

#12

+

#1

Mask image‐

Simple photometry

108 records/nightin a few minutes

Web
interface

Tomo‐e fast‐moving
object server

candidates

NEO
SQL
interfacedebrissatellite
・・・

Alerts offollow‐ups

Classifier based on
existing catalogues

meteors

Classifier based onmachine learning

AI
Bogus (artificial, seeing
dance, cosmic ray, etc.)
is rejected.

Satellite, space debris, and NEO catalogues

Photometry tablewith feature values3. Survey

Tomo‐e transient survey
Near earth objects (NEOs)
Cumulative number

are asteroids or comets with a closest
approach to the Sun (perihelion) of <1.3 au. Their orbits are evolved frommain belts.

1010

101

Diameter (km)
100
10‐1

10‐2

108
106

10‐1
10

Most of 10‐m sizes
are missing!

Model

103
105

104
102

Observations

107
109

100

Impact probability (year‐1)~ 100 small‐NEOs could be discovered per year.

reach the Earth's surface
Sun
Mars

NASA

Earth

Jupiter
Main belt

Tunguska event in June 1908

Chelyabinsk meteor in Feb. 2013

Planetary defense is necessary for keeping human civilization!

3. Survey
Yuto Kojima (Master’s thesis, U‐Tokyo)

Tomo‐e transient survey

Bogus (artificial, seeing
dance, cosmic ray, etc.)
is rejected.

Trial of survey for 10‐m size NEOs

= nearby fast‐moving object
Fast moving objects (v > 1”/sec)

Raw framesAI

Simpledetection

106 events~50 TBytes in 19 days with 21 sensors
NEO candidates
10 objects
orbit estimation> 3 times
detection

102 events
Catalogued NEO
0 events
45

Classifier based on
Random forest
machine learning

Catalogued artificial objects

true

103 events
Uncatalogued artificial objects withorbits similar to known artificial objects
New debris candidates

103 events
Visual inspection

OthersBogus (almost seeing dance)

102 events

2 x 102 events

2 x 103 events

3. Survey

Tomo‐e transient survey
Derived orbits and sizes
objectsize

arcfitting err(“) eP

Heliocentric orbit

closest distance

#1
#2
#3

rocks

#4

Ryugu

#5
#6

Geocentric orbit

#7
#8
#9

NEO follow up network: NEOAP, APAONNEO DB: MPC

Quick follow ups in a few hours are required to confirm NEO orbits.

Tomo‐e GW follow ups

GWs inO1 – O2

3. Survey

O3
O3

ER14: from Mar. 4 2019

O3

O3: from Apr. 1 2019https://www.ligo.org/scientists/G1801056‐v4.png

KAGRA

NS‐NS sensitivity

NS‐NS event rate †O2 (Mpc)

O3 (Mpc)

LIGO/Hanford (H1)

70



90

LIGO/Livingston (L1)

100



135

Virgo (V)

27



55

KAGRA
Reported on Feb. 15 2019

Tomo‐e Gozen GW follow‐
ups: from late Mar. 2019

8 ‐ 25(4 – 10) x 103 Gpc‐3 yr‐1 from O1‐O2
 1 /month max, 2/year med.
† BH‐BH: 1/month ‐ 1/week

NS‐NS localization
120 – 180 deg2 with 90% credible (med)10 – 20% of the area is localized < 20 deg2

Core members:

Tomo‐e GW follow ups
Wide‐field GW survey in O3

T. Morokuma, Y Niino (IoA, U‐Tokyo)
N. Tominaga (Konan U)
M. Tanaka (Tohoku U)
J‐GEM members

Light curves of GW170817
Arcavi 2018
@40 Mpc~100 deg2 ‐ 21 mag depth
•
•
•
•
•
•

‐
‐
‐
‐

(mag)
Targets: NS‐NS, and BH‐NS~100 deg2 sky
10
on‐source ~15 min exposure/pos[0.5 sec exposure] x 1,800 frames
Tomo‐e 15
Non‐galaxy‐targeted survey †no filter: effectively g+r@100Mpc† Other telescopes of J‐GEM teram
will observe galaxies < 100 Mpc.

Time‐resolution is selectable aftergetting data.

3. Survey@40MpcEarly phase of< 1hr in optical

Near infrared

20
25

g
B
1

R
V

10

When getting GW alerts, the observation mode will bechanged to the follow‐up mode immediately.

(days)

3. Survey

Tomo‐e GW follow ups

Survey patternwith Q1

Trials of GW follow‐ups with Tomo‐e Q1
in ER13 of LIGO/VIRGO (Dec 2018)• Automatically generate localization sky‐maps and observation
receipt files for Tomo‐e when getting ER13 test alerts.

Slack‐bot reports.

Flow chart for
ER13 tests

Sky map for test alerts
test GW

Tomo‐esky‐map

surveyFoV of Tomo‐eSuccessfully change
FoV to GW areas

3. Survey

Tomo‐e high‐speed programs

Duration time of flash (sec)CMOS

Field of View (deg2)100

26 100CCD

Tomo‐e Gozen

19

ZTF

22

1

flash
t

0.1

0.01

10

100

8.2m

24

1.8m
1.2m

20

19

17

10

count

2‐fps wide‐field movie survey
17 mag depth – 2Hz

1.0m

18
10

LSST

25

22
16

unexplored universe

PanSTARRS

20

23
18

1

0.1

1

10

14

iPTF

12

Decam
HSC

10

25 22 SDSSTAOS II

16

100

Temporal resolution (sec)
The numbers in the circles show limiting magnitudes.

0.01

0.1

1

1000

Apparent moving speed (arcsec/sec)Tomo‐e Gozen :PanSTARRS, ZTF :LSST :

0.5 sec/frame, Nread=2 e‐
30 sec/frame, Nread=5 e‐
60 sec/frame, Nread=10 e‐

3. Survey

Tomo‐e high‐speed programs
Fast spinning WDs
10,000 deg2, 2‐fps survey~300 WDs would be found.
P = 1 – 100 sec
Kashiyama, Kawana+Occultations of small
bodies A few events per year

Peculiar light curvesof exoplanets

WD+WD

Fast spinning
WD

Evaporating rocky planet?
Alien’s artificial planet?
Kawahara+t ~ 10 sec

Backgroundstar

Fast rotating asteroids

Km‐size objects outer Neptune Light curve
Duration time ~ 0.3 sec
Watanabe+

Seconds or shorter
timescale eventst

Phase variations on color
and albedo reflects theirformation history.
t ~ 1 sec
Urakawa+

Keplar’s light curve

Ultima Thule/NASA

Faint meteors

Unknown flashes

Interplanetary dust of < 1 mm
Use earth atmosphere as adetectorISSt ≪ 1 sec from
Ohsawa+/NASA

Optical counterparts of FRBs?
Unknown high‐energy burst?
Unknown objects near earth?
Unknown physics? t ≪ 1 sec

Unknown
unknown3. Survey

Tomo‐e high‐speed programs
High‐speed imaging of NEO
Urakawa+ 2019, AJ accepted
Near earth object 2012 TC4First faint‐meteor survey
Ohsawa+ 2019, Planetary and Space Science
Sample of bright meteor with drifting trail

Relative magnitude

Tomo‐e single sensor, 39.7’ x 22.4’, 2 fps
reproduction speed x200
Reproduced shapeand motion

17
18
model
19
0

Tomo‐e observations
6
12
Elapsed time (min)10‐m size

2012 TC4 was produced by impact events within ~3
x 105 year and has fresh surface.

Detection numberof meteor>1,500 events
detected in a night.
Brighter than 13 mag
Luminosity function of faint meteors is derived for the
1st time. The slope is consistent with brighter one.

3. Survey

Tomo‐e high‐speed programs
Congratulations! Hayabusa‐2 touch down on Ryugu

Hayabusa‐2 spaceship, JAXA

Image taken just after touch
down on the surface, JAXA

Memorial picture, AFP/JAXA@ 0.36 lunar distance from the earth

Image: JAXA
Dec. 3, 2015
Tomo‐e single sensor, 39.7’ x 22.4’, 2 fps
reproduction speed x10

Movie of Hayabusa‐2 taken by Tomo‐eGozen in the Earth swing‐by

3. Survey

Tomo‐e high‐speed programs
Test survey for single flash of t < 0.5 sec (= Tomo‐e flash)with 8 sensors• Data set (2 fps)
FieldsObservation time

Data size

framesHigh galactic latitude

6.0 hours

1.8 TBytes

43,000Virgo cluster

3.4 hours

1.0 TBytes

24,000• Detection and classification
Fields

Meteor

Cosmic ray

Elec. noise

Artificial obj.

othersHigh galactic latitude

87

140

14

107

7

Virgo cluster

121

59

5

28

3

repeated play

‐ Detected in only one frame, < 0.5 sec‐ Single event (not repeated), 16‐mag‐ Same PSF as other sources, ~3”

SDSS J122147.99+124935.5
galaxy1 sensor, 39.7’ x 22.4’
0.5 sec/frame‐ No color information obtained3. Survey

Tomo‐e high‐speed programs
Most Tomo‐e flashes would be from artificial objects
Low orbit satellite
160 – 2,000 km

Rotating debris

earth
Low orbit satellite
Geostationary orbit

Light from the Sun

NASA

Geostationary orbit
satellite, 36,000 km•

Space debris with φ 10‐mm on the geostationary orbit can be detected.

•

In earth’s shadow on the sky, no flashed are detected with Tomo‐e in an
additional observation run for 1 month.

But, we caught only one flash signal in the earth’s shadow!
What is this signal?

Space debris or Space treasures?

We will try to check again with full‐Tomo‐e.

in partial read mode

3. Survey

Tomo‐e very high‐speed programs
Detection of 10‐msec scale flares in the black‐hole binary MAXI J1820+070
Sako et al. 2018, Atel #11426

Absolute time accuracy:  0.2 msec

• 6.149 msec/frame, 1.6' x 0.79‘
15 sets of consecutive 10,000 frames
10 msec• 66.294 msec/frame, 9.9' x 7.1‘,
15 sets of consecutive 2,000 frames
0

0.5

1.0

1.5
2.0
Time (sec)

2.5

3.0

3.5

Simultaneous observations with Optical and X‐ray
56

58 60

62

64

66

68

70

Optical (Kiso/Tomo‐e)

X‐ray (Swift/XRT)

0

100

200

300
400
Time (sec)

500

600

Kokubo+ 2018, ASJ spring meetingin partial read mode

3. Survey

Tomo‐e very high‐speed programs
6.45‐msec resolution observations of Crab pulsar

Ichiki+2018, ASJ meeting• Kiso/Tomo, partial readout, 299” x 29”• UTC time synthesized by GPS（±0.2msec accuracy）• 6.45 msec/frame, ~50,000 frames
1 frame image (6.45msec exposure)

50,000 frame average image (total 322 sec exposure)

NIR imageCrabpulsar

Ref star

Photometry value (counts)

Periodic pulsations of 33.7 msec

50,000 frames
Light curve at the pulsar position

Time

σ

Folding analysis
P=33.73792msec

Holding analysis with P=33.73792msec
Differential image (perk - out of peak)Pulsation clearly
detected

M1 Crab nebula ( Supernova remnant)frames58

Plans‐ Simultaneous observations of giant pulses of Crab pulsar with radio and X‐ray telescopes.
‐ Optical survey for periodic pulsations in milky way fields.

SUMMARY of the Tomo‐e Gozen
Instrument
•
•
•
•
•
•
•
•

1‐m Kiso Schmidt telescope
20 deg2, 2 fps
84 chips of 1k x 2k CMOSs
30 TB per night
19 mag @texp=0.5sec
Optimized for discoveries of transients
Simple system
All of raw data is deleted in 7 days

Science targets

Full Tomo‐e Gozen will becompleted in spring 2019

• Tomo‐e transient survey, 10,000 deg2 every 2‐3 hours• GW optical counterparts• Fast moving objects, high‐speed monitoring59