Ground-based Wide Angle Cameras WEI Jianyan@SVOM Team NAOC, Beijing Les Chouches Physics School, April 11, 2016

Scientific requirements on SVOM Permit the detection of all know types of GRBs (>200), with a special care on high-z GRBs and low-z sub-luminous GRBs Provide fast, reliable and accurate GRB positions Measure the broadband spectral shape of the prompt emission (from visible to MeV) Measure the temporal properties of the prompt emission Quickly identify the afterglows of detected GRBs, including those which are highly redshifted (z>6) Quickly provide (sub-) arcsec positions of detected afterglows Quickly provide redshift indicators of detected GRBs

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 strategy: GRB optical emission detection T-T0=30 sec Wang et al 2013 GWAC GFTs VT

GWAC: an instrument for short time–scale optical transients Wozniak et al. 2009 The key point: trigger by its self !

Scientific objectives of GWAC Optical emission of GRBs Optical prompt emission ； Early optical afterglow Prior burst optical emission (if existing)； Other short time-scale Optical Transients(OT) Gravitational wave burst events Early light curve of SNs Tidal events of supermassive black holes Micro-lensing Neutrino bursts Near earth objects (NEO) Flare stars ……

GWAC System: Parameters Instruments: GWAC: 36 wide angle cameras with diameter of 18cm Mini-GWAC: 12 cameras with diameter of 7cm Follow-up telescopes: 2 dedicated 60cm telescopes Several dedicated 30cm telescopes

Prompt optical emission detection down to MV ~ 16.0 (10 s exposure) Parameters of GWAC Cameras： 36 Diameter： 180mm Focal Length： 220mm Wavelength： 500－800nm Total FoV： ~5000Sq.deg Limiting Mag： 16.0V（5，10sec） Self Trigger: ~13*5sec Prompt optical emission detection down to MV ~ 16.0 (10 s exposure)

Status: GFT for GWAC 2014-2015: two 60cm, from GuangXi Uni. 2015： one 30cm, from Huaibai Normal Uni.

Status: Mini-GWAC Mini-GWAC at Xinglong Obs.: 12 CANON EF 85/f1.2 12 U9000X CCD cameras FoV: ~5000 Sq.Deg Limiting Mag: ~12.5mag Having capability to trigger OT: Oct. 2015: in operation， ~10 flare stars detected, … 2015.12.18：a Flare star，Time scale~700秒 2013.05.28 Light curve

------------------------------------- Light curves of GRBs （Wang et al. 2013） A light curve of a flare star （Mini-GWAC 2015） ------------------------------------- T0 T-T0=30 sec -------------------------- Mini-GWAC -------------------------- GWAC -------------------------- 700sec

GRB prompt detection efficiency Sites for GFTs and GWAC GRB prompt detection efficiency C-GFT GWAC F-GFT GWAC

GWAC Follow-up Observation Strategy 2M Telescops ~10Min T R I G E Follow-up M U L T B A N D ~1min ~1day P O T M E R Y S W I F T ? + 1M NetWorks ~1hr GWAC 60/30CM

2015.12.18: early spectra from the 2.16M

GRB140629A ：Spectrum from 2.16M@~1hr Z=2.275

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

March 2015: MoU between SVOM and LIGO/VIRGO

2015.12.26：Mini-GWAC first pointed to G211117 The report to LIGO Mini-GWAC covered the north sky LIGO/Virgo G211117: List of near-term future observation regions by Project Mini-GWAC of SVOM J.Y. Wei (NAOC), C. WU(NAOC), N.Leroy (LAL), L.P. Xin (NAOC), X.H. Han (NAOC), X.M. Meng(NAOC), L. Huang(NAOC), Y. Xu(NAOC), H.B. Cai(NAOC),J. Wang(NAOC), X.M. Lu(NAOC), Y.L. Qiu (NAOC), J.S. Deng(NAOC), L. Cao(NAOC),S. Wang(NAOC), E.W.Liang (GXU), Y.G. Yang (HBNU), B. Cordier(CEA),S.N. Zhang (NAOC),S. Basa (LAM), B.B. Wu(IHEP), Jean-Luc Atteia (IRAP), D. Götz (CEA), Cyril Lachaud (APC) on behalf of the SVOM Gravitational Astronomy group report: We observed about 3200 square degree (8 sky regions) of the skymap of the advanced LIGO and Virgo trigger G211117, with Mini-GWAC(Mini Ground Wide Angle Camera), at Xinglong Observatory of NAOC equipped with U9000 camera(FOV~400 square degree/camera). Mini-GWAC comprises of 12 wide field angle cameras(aperture=7cm), working with unfiltered band. The observations are operated in time-series mode, taking one exposure in 15 seconds (10s exposure + 5s readout). The limit magnitude is ~12 mag in R band. The coordinates of the 8 regions and observation time are list following:

Current Status and Schedule Mini-GWAC 2011-14: ready for observation GWAC 2010-11：dome at Xinglong Obs. 2010-12：40 CCD chips 2010-13：engineering models 2012-14: Pipelines ( V1.0) 2015-16： 1/2 of GWAC 2017： 1/2 of GWAC Follow-up telescopes 2015: two 60cm. 2015： one 30cm 2016-17: more 20cm Re-set up at Chile 2018/20： TBD Budget ~33 + ~30M ￥(10M USD) (~6000Sq.deg) 20M ￥ more? (~9000Sq.deg)

Summary GWAC is an dedicated instrument for short time scale optical transcients: 10~20 GRBs per year will be monitored; Several bursting SNs per year will be detected; A promising instrument to detect GW counterparts. Several years before SVOM launch: excellent chances to train BAs and Science Centers.

Engineering models of GWAC ----Camera(FoV + high image quality) + Mount

Camera design and manufacture Optical design 装配图

GWAC：大面阵e2v CCD Oct. 2010：signed contract with e2v July 2012: 40 4k4k back-illu. CCDs

Dowar with cooling system 2012.12.18 2013.1.4 -50C ！ Vacuum is stable Dowar with cooling system

Sept. 24,2014, New Dowar, -70C! 目标温度：-71C 冷端：-71C 热端：+32.7C V：8.37V I：5.38A 平稳态 Sept. 24,2014, New Dowar, -70C! 目标温度：-50C 冷端：-49.9C 热端：+25.8C V：5.75V I：3.52A 目标温度：-70C 冷端：-66.1C 热端：+47.3C V：13V I：9.6A 全力上升中 目标温度：-71C 冷端：-71C 热端：+30.0C V：7.64V I：4.91A 当若真空度很好

10-6 ？？ ？ Visible Detection prompt emission in visible will extend 3-4 orders to low energy band, to provide new chances to understand GRBs.

Comparing with the Existing Instruments FoV(Sq.Dec.） Lim. Mag. Reference WIDGET (Japan) 4000 12 Urata et al 2010 Pi of the Sky (Poland) 1600*n Sokolowski et al 2009 TORTORA (Russia) 720 11 Greco et al.2009 RAPTOR-Q (USA) ～15000 9.5 Woznizk et al. 2009 Mini-GWAC (China) ~5000 12.5 Wei at al. 2015 GWAC (China) ～5000 16.0 Wei et al. 2015 GWAC is 2~3 orders more powerful !