GWAC (Ground Wide Angle Cameras) Liping Xin National Astronomical Observatories, Chinese Academy of Sciences Collaborators: Jianyan Wei (PI), Yulei Qiu, jingsong Deng, Chao Wu, Hongbo Cai, Lei Huang, Xuhui Han, Huali Li et al. 2013/5/17 KIAA multi-messager transient workshop 1
GWAC A ground-based system of SVOM (talk by Jianyan Wei) Cameras: ~72 (36 + 36) Diameter: ~18cm Mounts: ~18 (9 + 9) (4Cameras/mount) Wavelength: ~ 450-900nm Combined FoV: ~9000 (4500 + 4500) Sq.deg Limiting Mag: ~15.5-16.5V(5, 10sec) Groups: 2 ( each with 36 cameras ) 2013/5/17 KIAA multi-messager transient workshop 2
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Fig. presents different processes and time evolution of a GRB There is a critical time for the obs, named as trigger time (T 0 ) : 2013/5/17 KIAA multi-messager transient workshop 6
Fig. presents different processes and time evolution of a GRB There is a critical time for the obs, named as trigger time (T 0 ) : After T 0, afterglow ------ know a lot prompt emission ------ know a little Before T 0,??? ------ know little 2013/5/17 KIAA multi-messager transient workshop 7
Akerlof et al. 1999 1. Reverse shock at the prompt phase 2. Information of the first 30 ses is missed 2013/5/17 KIAA multi-messager transient workshop 8
Vestrand et al. 2005 1. A very long burst with about 500s duration. 2. The first observation was about 100s after the trigger, though the optical observations almost cover the main burst region 3. What does the optical emission looks like before the first obs? 2013/5/17 KIAA multi-messager transient workshop 9
080319B Racusin et al. 2008 1. A very lucky burst, a right GRB happened at a right time at a right location. The optical emission is very bright, which is about 5 mag in V band The difference of trigger times for both were about 30min. The distance between GRB080319A and GRB080319B is only about 10deg. Most of telescopes are in the state of obs of 080319A, and could very quickly move to the 080319B. 2. As a result, a no delay obs of the brightest GRB were recorded. 2013/5/17 KIAA multi-messager transient workshop 10
Recent burst GRB 130427A Swift trigger: 07:47:57UT Fermi GBM, LAT also detected Redshift 0.34 http://www.swift.ac.uk/xrt_products/ 2013/5/17 KIAA multi-messager transient workshop 11
Recent burst GRB 130427A Swift trigger: 07:47:57UT Fermi GBM, LAT also detected Redshift 0.34 RAPTOR, GCN 14476 http://www.swift.ac.uk/xrt_products/ 2013/5/17 KIAA multi-messager transient workshop 12
Recent burst GRB 130427A Swift trigger: 07:47:57UT Fermi GBM, LAT also detected Redshift 0.34 RAPTOR, GCN 14476 http://www.swift.ac.uk/xrt_products/ 1. Top 2 brightest GRBs (According to the report by Wren etal. GCN 14476) 2. High emi before the trigger time 2013/5/17 KIAA multi-messager transient workshop 13
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At least 15% bursts have the precursors (talk by En-Wei Liang) A type of telescopes independent with the trigger are needed. One choice: Wide FOV telescope 2013/5/17 KIAA multi-messager transient workshop 19
Fermi GBM burst Lots of knowledge were obtained from the observations by Fermi GBM. Time delay of GeV photons relatively to the MeV. GeV light curve might come from external shock, like the low-e emi. (xray and opt.) A caveat is that the uncertainty of the localization ability 88% ~3.6deg; 12% ~ 13.9 deg; (talk by Briggs) Most of telescopes could not follow-up Only telescopes with wide FOV have potential to do. 2013/5/17 KIAA multi-messager transient workshop 20
Optical transients with other events GWAC: potential to catch the optical counterpart related with: NS-NS mergers (talk by Li-Xin Li, Bing Zhang, Xuefen Wu et al,) GW alerts (talk by Osborne) Neutrinos bursts Others 2013/5/17 KIAA multi-messager transient workshop 21
Possible short-duration optical transients? Kulkarni 2009 Wozniak et al. 2009
Science for GWAC 1. GRB related prompt emission (Swift, Fermi, SVOM et al. ) External shock: RS and FS Precursors Optical emission related with GBM burst 2. Optical counterpart related with other processes GWB (talk by Bing Zhang, Xuefeng Wu et al. ) Shock break-out of SNs Optical flares from Neutron star mergers (talk by Li-Xin Li), 3. Other short-duration optical transients (stellar flares et al. ) 4. Unexpected events 2013/5/17 KIAA multi-messager transient workshop 23
Current status of GWAC 2013/5/17 KIAA multi-messager transient workshop 24
The design concept of one unit of GWAC
CCD chips for GWAC
One set:36 telescopes and 9 mounts
Xinglong observatory of China 2013/5/17 KIAA multi-messager transient workshop 28
GWAC dome 2011.05 2011.08 2011.10 2011.12
Performance of GWAC prototype 2013/5/17 KIAA multi-messager transient workshop 30
Operating mode of GWAC The first principle is to monitor the sky continuously 15s ( 10 sec exposure + 5 sec readout ) Observational modes: Survey mode (Most of time) Alert mode (Fermi GBM burst, GW, Neutrino ) Real time data processing are needed for GWAC data for any transients. Analysis of each image should be done within 15 sec. 2013/5/17 KIAA multi-messager transient workshop 31
Two 60cm multi-color telescopes -----A contribution to SVOM by Prof.Liang from GXU Confirming GWAC OT: Sub-arcsecond localization Multi-color diagram High time resolution light curves 2013/5/17 KIAA multi-messager transient workshop 32
GWAC 2013.12 Current GWAC 2014.12 GWAC 2016 ( Planed )
~ 50,000 stars with U9000X CCD >100,000 stars with e2v CCD Test img. 9*9 Sr deg2 2013/5/17 KIAA multi-messager transient workshop 34
Pipeline for data reduction Has been developed, including Source extraction Astrometry Search the new objects by cross match and by subtract images Photometry Confirmation Classification Sent out the detection alerts to dedicated telescopes. Test and optimization is on-going. 2013/5/17 KIAA multi-messager transient workshop 35
Reference New 2013/5/17 KIAA multi-messager transient workshop 36
Reference New 2013/5/17 KIAA multi-messager transient workshop 37
Double stars Mira Variable 2013/5/17 KIAA multi-messager transient workshop 38
Minor-planet in FOV of GWAC at Dec 05 th 2012 6x6 arcmin. 10:55:47 ~ 14:13:10 00:33:05.5, +21:55:58, J2000 V~15.3 Shift 5.6 pixels in 3.3 hours 2013/5/17 KIAA multi-messager transient workshop 39
Recall the GWAC performance Cameras: ~72 (36 + 36) Diameter: ~18cm Mounts: ~18 (9 + 9) (4Cameras/mount) Wavelength: ~ 450-900nm Combined FoV: ~9000 (4500 + 4500) Sq.deg Limiting Mag: ~15.5-16.5V(5, 10sec) Groups: 2 ( each with 36 cameras ) 1. For an object brighter than R~11 mag, it will be saturated in the GWAC image. 2. Need a system to test all technologies and software, including pipeline 2013/5/17 KIAA multi-messager transient workshop 40
GWAC Cameras: ~72 (36 + 36) Diameter: ~18 cm Mounts: ~18 (9 + 9) (4Cameras/mount) Wavelength: ~ 450-900nm Combined FoV: ~9000 (4500 + 4500) Sq.deg Limiting Mag: ~15.5-16.5V(5, 10sec) Groups: 2 ( each with 36 cameras ) Mini-GWAC Camera: ~12 (Canon EF 85mm f/1.2) Diameter: ~7 cm Mounts: ~6 (2Cameras/mount) Wavelength:~ 400-800nm Combined FoV:~4800 Sq.deg Limiting Mag:~12.7V(5,10sec) 2013/5/17 KIAA multi-messager transient workshop 41
Mini-GWAC Hope to work at this Sep. 2013/5/17 KIAA multi-messager transient workshop 42
The whole system Mini-GWAC GWAC Follow-up photometry spectra 2013/5/17 KIAA multi-messager transient workshop 43
Leonids meteor shower observed by GWAC at Nov.18 th 2012 2013/5/17 KIAA multi-messager transient workshop 44