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Huang_Kuiyun Powered By Docstoc
					Hunting GRB Early Optical
Emission with TAOS Telescopes

               Kuiyun Huang
   Academia Sinica, Institute of Astronomy
      and Astrophysics (ASIAA),Taiwan
        TAOS Project
(Taiwan-America Occultation Survey)
No significant events were
found in the first two years
 Present upper bound to the
  size of KBO
  ( 0.5km < D < 10km)
 Construct TAOS 2 project

                Zhang et al. 2008
    Special Features of TAOS project
 Four robotic telescopes (50cm, F/1.9 Cassegrain)
 2k x 2 k CCD Camera (EEV CCD 42-40)

 Field of View ~ 1.7 degree x 1.7 degree

 Pixel size ~ 3 “

 Filter : 5000-7000 A (near R band )

 Observational Mode

  – Zipper mode (0.2 sec exposure)
  - Stare mode
 Nearly real-time processing /correlation among telescopes

 Response to GCN (GRB Coordinate Network) alert

   in 1 min
TAOS GRB Alert System

 • Exposure time : 0.2s, 1s, 5s, 25s
 • Follow-up time : 30 minutes
    TAOS GRB observations in 2006-2007

(1) GRB 071010B                    (2) GRB 071112C
   Duration : 35s                    Duration : 15s
   Afterglows : XT, OT               Afterglows : XT, OT
   Redshift : 0.947                  Redshift : 0.823
   Response telescopes :             Response telescopes :
 TAOSA(1s),TAOSB(5s),TAOSD(25s)        TAOSA(1s),TAOSB(5s)
Response time :                   Response time :
  52s after trigger                 94s after trigger
  38s after alert
                                    41s after alert
 Fastest response in this event
                                   Time coverage : 94-4000 s
 Time coverage : 63-230 s
GRB 071010B                   (Wang, Schwamb & Huang et al. 2008)

   No significant correction with the prompt -ray emission

   Optical afterglow light curve up to 2 days after the burst

Use Equations of Molinari et al. (2007)
Tpeak ~ 158 s
Initial Lorentz factor Γ0 ~ 164 (ISM), Γ0 ~ 31 (Wind)
GRB 071112C

                                         α = -0.81+/- 0.02

                            (Stratta et al. 2007)

                  α = -1.36+/- 0.01

              α = -1.6+/- 0.1
Advantages for GRB Observations
(1) Fully automated observing system
   -- Telescopes can have quick response to GRBs
   -- Alert software has established to manage GRB
      alerts and send observing commands to telescopes.
(2) Four 50cm-telescopes at same site
   -- Follow-up with different exposure time
   -- Obtain high time resolution light curve in early
      afterglow phase.

Probe early optical emission of GRBs
   Two components of optical emission during the first
     few minutes (Vestrand et al. 2006)
(a) The prompt optical emission
        Correlated with prompt gamma-ray emission.
       Could probe isolated jet from the surrounding medium
(b) The early optical afterglow emission
       Uncorrelated with prompt gamma-ray emission
       Strongly depends on the nature of medium
      T90 =520s                            T90 =110s
        Thank You!

                             TAOSA, TAOSB


                                      Lulin 1-m

TAOS Observing Hours (2005–2006)
TAOS Telescopes
    TAOS Shutter-less Zipper Mode

snapshot                                  charge
w. time tag                               transfer
(1 to 4)                                  (downward)

                                          block readout
 state)          a more realistic case…

                                          zipper image
                                          (a stack of

(steady state)

                 data taken on 21 February 2004 (UTC)
 GRB 050820A : The first case shows the two
               optical components
Prompt optical emission
                                                        (1) Prompt emission
Afterglow emission                                        broad-band spectra could
                                                          constraint evolution of jet

Afterglow emission                                      (2) Afterglow emission
                                                            Afterglow of secondary
                                                            energy release could
                                          major burst
                            T90 = 85s                       merger the fading
                                                            primary afterglow
                                                             probe evolution of the
                          initial burst                         interaction
                                                             how the GRB
                                                               environment is modified

                                                         Vestrand et al. Nature 2006 422, 172
                         THE TAOS TEAM
Institute of Astronomy & Astrophysics and Institute of Earth Sciences, Academia Sinica, Taiwan
                                           Typhoon Lee(IES PI), Chi-Yuan(IAA PI), Sun-Kun King,
                                                     Andrew Wang, Shang-Yu Wang, Chih-Yi Wen
Institute of Astronomy, National Central University, Taiwan
                                  Wen-Ping Chen, Yung-Shin Chang, Soumen Mondal, Kiwi Zhang
Harvard-Smithsonian Center for Astrophysics, USA
                                Charles Alcock, Matthew Lehner, Federica B. Bianco, Rahul Dave
The Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, USA
                                                                                          Kem Cook
Yonsei University, Department of Astronomy, South Korea
                                                                                       Yong-Ik Byun

Department of Physics and Astronomy, University of Pennsylvania, USA        Joseph Giammarco
University of California, Berkeley, USA                                Imke de Pater, John Rice
Stanford Linear Accelerator Center, USA                                        Stuart Marshall
Steward Observatory, The University of Arizona, USA                                Tim Axelrod
Ames Research Center, National Aeronautics & Space Administration, USA           Jack Lissauer