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TAROT (Télescope à Action Rapide pour les Objets Transitoires). Michel Boër CNRS – Observatoire de Haute Provence. Les sursauts gamma (GRB). Une explosion rapide suivie d’une décroissance graduelle Evènement prompt Détecté en gamma par les satellites Dure de 0.01 à 1000s - PowerPoint PPT Presentation
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TAROT(Télescope à Action Rapide pour les Objets Transitoires)
Michel BoërCNRS – Observatoire de Haute Provence
ASTEP - 05/09/06 M. Boer, OHP
Les sursauts gamma (GRB) Une explosion rapide suivie d’une
décroissance graduelle Evènement prompt
Détecté en gamma par les satellites Dure de 0.01 à 1000s 2 populations (0.5s et 30s)
Partie rémanente, décroissante en t-
1,-2
~ 2 GRB/j >10-8erg/s.cm-2 .4πSter SWIFT 150/an, GLAST 400/an Taux local ~2 Gpc-3 yr-1
Evènements Panchromatiques: Emission maximale entre < 10 and
1000 keV Détectés entre 1mkeV to >? 20 GeV)
Très variables (< 10ms) Origine cosmologique (0,001 < z <
6,29 (measured) < 15??) Très lumineux: 1051-52ergs (mais
émission en jets)
ASTEP - 05/09/06 M. Boer, OHP
Le modèle de la boule de feu
106 cm
t-1
1016 cm
1013 cm
taft
Emission rémanente
RB
tGRB
ASTEP - 05/09/06 M. Boer, OHP
Une chaîne pour la détection
8s
0,5s
HETE
position
Pointageobservation(1s)
INTERNET
VHF
ASTEP - 05/09/06 M. Boer, OHP
Tarot today
ASTEP - 05/09/06 M. Boer, OHP
A fully automated telescope
ASTEP - 05/09/06 M. Boer, OHP
Data processing (see A. Klotz)Automated correlation with USNO catalogAutomated image comparison for variable objects
ASTEP - 05/09/06 M. Boer, OHP
TAROT & SWIFTDiameter 25 cm
Speed F/3.5
Pointing time 1-2 sec. (60 °/s)
Acceleration Up to 120°/s2
Limiting magnitude V = 16.2 in 10 sec.
CCD type EEV 42-40 BI
CCD size 2048 x 2048 (3 x 3 cm)
Op. CCD temp. -45°C
Readout speed 5s
Typical integration time 10 to 180s (GRB)
Readout noise 8.5 e-
Field of view 1.86 degrees
ASTEP - 05/09/06 M. Boer, OHP
SWIFT GRBs observed by TAROTEvent Tobs after
triggerMagnitude
GRB 050306 (z = ?) 90s R > 17.5
GRB 050416 (z = 0.65) 8h25 R > 19
GRB 050505 (z = 4.2) 540s I = 18.2
GRB 050525a (z = 0.6) 360s R = 15.0
GRB 050730 (z = 3.97) 66s I = 15.5
GRB 050803 (z = 0.42) 61min R > 19
GRB 050824 (z = 0.83) 600s R = 18
GRB 050904 (z = 6.29) 86s I = 14.1
GRB 051211b (z = ?)(INTEGRAL)
12s R = 16.2
GRB 051221 (z = ?) 281s R > 18
GRB 060111b (z = ?) 28s R = 13.2
GRB 060124 (z = 2,30) 7198s R > 18.5
GRB 060717
GRB 060904A 26.8s R > 19.5
GRB 060904B (z = 0.703) 23.1s R = 15.8
ASTEP - 05/09/06 M. Boer, OHP
GRB 050904
• Event at 01:51:44
• T90 = 225s
• First image at 01:53:10 (TAROT reaction time 4s) 86s after event started
• Last at 1666s• First images stacked to
increase sensitivity• Field observations
performed at OHP to calibrate frames
ASTEP - 05/09/06 M. Boer, OHP
GRB 050904 & GRB 990123• Plateau observed for GRB 050904 may have been missed for GRB
990123 because of dead-time– Plateau + flare: how to explain them within context of refreshed shock or
reverse shock?– For the future need of better sampling and less dead time
• Luminosity of GRB 050904 (1054erg) comparable to GRB 990123 (2.4 x1054erg)
• Behavior of both events quite similar• Suggest class of optically bright OTs
– May be used for detection up to very high redshifts even with small / moderate telescopes
– Allow fast, 1s, sampling and easier spectroscopy– Should be confirmed by other events: TAROT data suggest that other
events may be bright OTs (050505 & 050730) • Recent work (Gendre et al. 2006) shows evidences for a fireball
expanding in the early wind of a massive star: observation of a star at z = 6.29
ASTEP - 05/09/06 M. Boer, OHP
Sensitivity vs. continuous imaging
• Tracked drift mode– Drift mode at 3.33 s/pixel
rate– Drift image lasts 60s, i.e.
18 pixels of continuous monitoring
– Following images are non-trailed (sidereal tracking on), 30 to 180s, 5s dead-time
– For GRB 060111b, USNO star used as comparison
ASTEP - 05/09/06 M. Boer, OHP
The light curve• GRB 060111b
– 20:15:43 UT– Close to the Moon– No redshift available but
• UVOT detection (5min), z < 3• B&G relation gives z = 2, but invalid if z
< 0.5– Continuous monitoring from 28 to 88s– From 28 to 61, sampling = 1px = 3.33s,
after binning over 4pix = 13.3s• Smooth!
– Continuous, fast decay from Ttrig + 28 to 90s: 2.4
– No evidence of flare at time of gamma-ray second peak
– Then shallower decay 1.12, typical AG– If 1 component, Tbreak = 80s– If 2 component:
• Alpha1 = 3.0• Alpha2 = 0.89• Ttrans = 65s !
ASTEP - 05/09/06 M. Boer, OHP
TAROT: a versatile telescope
• In summary– A relatively sensitive instrument– Wide field– Designed for variable objects– Large availability, advanced scheduler– Versatile, very easy to use– One of the rare fully automated telescopes
• Full autonomus operations, supervision possible• Advanced scheduler, multi purpose (e.g. satellites, stars, GRB,
periodic…), now multi-telescope• On-line data processing, automatic search for variable and transient
objects• Archiving and automatic transfer• Immediate results and images availability on the web• Immediate dissemination of transient position (web, e-mail, sms)
ASTEP - 05/09/06 M. Boer, OHP
Scientific programs
• Variable star catalog– All fields were searched for variable– Catalog of 2000 objects being published – Fully automated blind search
• Specific objects (RR Lyr)• Supernovae• AGNs• Solar system objects (binary asteroids…)• Orbital environment (satellites and debris)
ASTEP - 05/09/06 M. Boer, OHP
TAROT variable star catalog
(Damerdji, Klotz and Boër, 2006)
ASTEP - 05/09/06 M. Boer, OHP
Present and future
• Enhance archiving and data acces
• New release of automation program
• Now, automated dissemination of results
• TAROT-Chili is being installed at La Silla
• Work with 2 telescopes in synchrone mode, another telescope planned (Australia)
• Within the framework of SVOM/ECLAIRs, OHP leads the team for the 1.50m follow-up telescope
ASTEP - 05/09/06 M. Boer, OHP
TAROT experience for ASTEP
• TAROT has becomed a very efficient instrument– Though small, able to give cutting edge scientific results
• Experience gained in automated instruments• TAROT are non-attended instruments
– System approach– Reliable hardware (specific opto-mechanical design,
control/command)– Reliable software– Failure rate very low (i.e. high efficiency)– Advanced scheduling (multi-telescope)– Automated processing and archiving– Diverse types of requests– Now advanced scheduler for both instruments
• This experience can be transfered to ASTEP