1. EM counterparts of GWs:
Observation Strategy of SVOM Mission
WEI Team NAOC, Beijing
7th Jan. 2019, Xiamen

2. Outlines
A short introduction about SVOM
GW EM counterparts observation strategy

3. Status of the SVOM mission
2001
SVOM proposed by Chinese side, Eclairs by French side
2006
Phase 0 kick-off meeting (March, Toulouse)
Phase 0 review (Sept., Shanghai)
CNSA/CNES MoU signed during the President visit (Oct., Beijing)
2007
Phase A kick-off meeting (March, Xi’an)
2008
Phase A review meeting (Oct., Beijing)
2010
SVOM funded by CNSA China
2014
SVOM funded by CNES France
2014
Phase B kick-off meeting (Sept., Shanghai)
2016
Phase B review meeting (July 4-8, Yantai)
2017
Phase C kick-off meeting, and SIR review
2021
SVOM launch at Xichang（西昌）, China

4. Scientific rationale of a new GRB mission
GRB phenomenon
Diversity and unity of GRBs
GRB phenomenon
Diversity and unity of GRBs
GRB physics
Acceleration and nature of the relativistic jet
Radiation processes
The early afterglow and the reverse shock
GRB physics
Acceleration and nature of the relativistic jet
Radiation processes
The early afterglow and the reverse shock
The GRB-supernova connection
Short GRB progenitors
GRB progenitors
The GRB-supernova connection
Short GRB progenitors
GRB progenitors
Cosmology
Tracing star formation
Re-ionization of the universe
Cosmological parameters
Cosmological lighthouses (absorption systems)
Host galaxies
Cosmology
Tracing star formation
Re-ionization of the universe
Cosmological parameters
Cosmological lighthouses (absorption systems)
Host galaxies
Fundamental
Origin of high-energy cosmic rays
Probing Lorentz invariance
Short GRBs and gravitational waves
physics
Fundamental
Origin of high-energy cosmic rays
Probing Lorentz invariance
Short GRBs and gravitational waves
physics

5. The first stars and the baby Universe
Now
～13.8Byrs
Evolution after the big bang
1010
109
108
107
106
105
Re-Iron.
Big Bang
Sun
Dark Age
last diffusion limit
Pop III 3 10 30
100
300
1000
3000
1 + z

6. Proposed scientific instruments
ECLAIRs, the X-ray and soft gamma-ray trigger camera
4-250KeV sr (~8000 Sq.deg)
GRM, the gamma-ray spectro-photometer
15KeV-5MeV 60 Deg
MXT, the micro-channel soft X-ray telescope
0.3-6KeV ’65’
VT, the visible telescope
nm, nm 26’26’
GWAC, an array of ground wide angle cameras
nm ~ 5000 Sq.deg.
C-GFT, the Chinese ground follow-up telescope
nm? ’25’
F-GFT, the French ground follow-up telescope
nm ’30’

7. SVOM scientific instrument arrangement
( SVOM white paper)

8. ECLAIRs: the trigger camera
Main characteristics
Coded mask telescope
Wide FOV : 2 Sr
6400 CdTe cm2
4 keV – 150 keV
Anticipated performances
Loc. accuracy < 10arcmin
3 arcmin for bright burst
70 GRBs / year

9. GRM – The Gamma Ray Monitor
Main characteristics
NaI detectors
FOV : 60 Deg.
10 keV – 5 MeV
Anticipated performances
Loc. accuracy ~ 2°
100 GRBs / year

10. MXT – The Multi-channel X-ray Telescope
Main characteristics
MCP X-ray optic
FOV ~ 1 deg2
256 x256 PN CCD
0.3 keV – 6 keV
Anticipated performances
Loc. accuracy < 1 arcmin
20 arcsec for bright GRB
5x10-12 erg cm-2 s-1 in 1000s

11. VT – The Visible Telescope
Main characteristics
Ritchey Chretien Ф=40cm
FOV : 26 x 26 arcmin2
2 X 2048x2048 CCD
/ nm
Anticipated performances
Loc. accuracy ~1 arcsec
Mv = 22.5 in 300s

12. Parameters of the GWAC at China
Cameras：
Diameter： mm
Focal Length： 220mm
Wavelength： －800nm
Total FoV： ~6000Sq.deg
Limiting Mag： 16.0V（5，10sec）
Self Trigger: ~13*5sec
Prompt optical emission detection down to MV ~ 16.0 (10 s exposure)

13. Space instruments performances
Spectral band
Field of View
Allocation Accuracy
GRBs/yr
(Dect. Rate)
GRM
30keV-5MeV
2 sr
Not applicable
~100
ECLAIRs
4-250 keV
10 arcmin
~70
MXT
0.3-5 keV
65 65 arcmin
30 arcsec
~90% VT nm nm
26  26
arcsec
1 arcsec
~80%

14. Pointing strategy: anti solar
Sun
Night side
SVOM orbit (i ~ 30°)
About 75% of the GRBs detected by SVOM to be well above the horizon
of large ground based telescopes all located at tropical latitudes

15. Prompt dissemination of the GRB parameters
VHF Network

16. GRB observation strategy
Space
GRB trigger provided by ECLAIRs at time T0
GWAC
GFTs (g, r, i, J, H), LCOGT
T0 +1 min
1-2 m robotic telescopes
VT (V & R band photometry)
MXT (Soft X-ray photometry)
T0 + 5 min
Ground
Multi messenger follow-up

17. SVOM repartition: useful observing time

18. Multi-wavelength capabilities of SVOM
102
103
104
105 10 1 -5
1022
1020
1016
1018
1014
1015
Time (s)
Log. scale
Time (m)
Lin. scale
Frequency (Hz)
Space
Ground
Slew
GRM
ECLAIRs
MXT VT
GWAC
F-GFT
C-GFT
SVOM: also a powerful multi-band observatory for transcients!
GWs will be followed within 12 hours.

19. The strategy for SVOM to observe GW bursts
2015
2019
2022
Error box: ~600 Sq.Deg
~<10 Sq.Deg.
GRM
Eclairs
MXT VT
GWAC

20. GW / GRB A
Would this GRB Have been detected by SVOM?
ECLAIRs
GRM 
Up to 35°: ECLAIRs detects and localizes the GRB
ECLAIRs sends an and a slew reques
to the satellite
 Up to 50°: GRM sends an alert (coarse location)
SVOM JSC – December 6th - Paris

21. GW / GRB A
ToO-MM
The associated kilonova would have been easily detected by the VT and the GFTs From T0 + 2 hours and for 10 days
SVOM JSC – December 6th - Paris

22. Status: GWAC 2013-2016: Mini-GWAC for developing Pipelines V1.0;
: two 60cm, one 30cm telescopes from GXU and .
: the first 18-GWAC system (10 telescopes from NJU);
: the 16-GWAC in testing; 22-GWAC waiting for check

23. An example：2015年12月18日发现---耀星

24. -----------------------------------
GRB
（Wang et al. 2013）
Flare star
（Mini-GWAC 2015） T0
T-T0=30 sec
GWAC
600秒

25. 2.16-M follow a flare star： 2015年12月18日发现的耀星

26. So far more than ~60 flare stars were triggered by GWAC/Mini-GWAC

27. 2017 -2018 SVOM Follow-up testing system SVOM CFHT
Mini-GWAC，GWACs, F-60A,B
CFHT
Obs. time
SVOM
Scheduler
Database
Server
Scientific expertise
Xinglong 2.16M
Lijiang 2.4M

28. 7 GWs followed during O2 name circular First exposure G268556_20170104
mini:1 + F60B:1
+2h20min
G2*******************
Mini:1 + GMG:1
+20mins
Mini:1
+6h20min
-5h29min
+2d16hrs
+12h30min
+12h2min

29. O1: GW151226 O2: GW170104 6 other events 10 GCN circulars
(其中2个使用2.16m 和2.4m )
8/1/2019

30. SVOM Follow-up testing system
CFHT
Obs. time
SVOM
GWACs, C-GFT
GRANDMA
Lite Database
Server of pointings
OT sc. products
SVOM
Pointing generator
Database
ZADKO
TAROT
Xinglong 2M
Lijiang 2.4M
LCOGT
SVOM testing system
Follow the strategy of SVOM
Smoothly evolve to SVOM 2021

31. Voluntaried Facilities
SVOM Follow-up System
2021
SVOM
ECLAIRs, VT,MXT,GRM
GWACs, C-GFT, F-GFT
SVOM
Scheduler
Database
Server
Scientific expertise
Voluntaried Facilities
Guaranted time
Time to Apply
Time to buy
TAROT
LCOGT 1m
CFHT
LCOGT 2m
XXX Obs
Lijiang 2.4M
VLT
UKIRT
XXX Obs
XXX Obs
XXX Obs
XXX Obs
Organization of the SVOM Follow-up system, operational in 2021? and based on the attractiveness of SVOM
The exchanges between SVOM and its various partners are (will be) defined in the updated SVOM Science Management Plan