TAROT Télescope à Action Rapide pour les Objets

TAROT (Télescope à Action Rapide pour les Objets Transitoires) Michel Boër CNRS – Observatoire de Haute Provence ASTEP - 05/09/06 M. Boer, OHP

Les sursauts gamma (GRB) Ø Une explosion rapide suivie d’une décroissance graduelle Ø Evènement prompt Ø Détecté en gamma par les satellites Ø Dure de 0. 01 à 1000 s Ø 2 populations (0. 5 s et 30 s) Ø Partie rémanente, décroissante en t-1, -2 Ø ~ 2 GRB/j >10 -8 erg/s. cm-2. 4πSter Ø SWIFT 150/an, GLAST 400/an Ø Taux local ~2 Gpc-3 yr-1 Ø Evènements Panchromatiques: Ø Emission maximale entre < 10 and 1000 ke. V Ø Détectés entre 1 mke. V to >? 20 Ge. V) Ø Très variables (< 10 ms) Ø Origine cosmologique (0, 001 < z < 6, 29 (measured) < 15? ? ) Ø Très lumineux: 1051 -52 ergs (mais émission en jets) ASTEP - 05/09/06 M. Boer, OHP

Le modèle de la boule de feu 1016 cm 1013 cm 106 cm g RB G 2 t-1 Emission rémanente G 1 t. GRB taft ASTEP - 05/09/06 M. Boer, OHP

Une chaîne pour la détection HETE position 8 s VHF 0, 5 s INTERNET Pointage observation (1 s) 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 catalog Automated image comparison for variable objects ASTEP - 05/09/06 M. Boer, OHP

TAROT & SWIFT Diameter Speed F/3. 5 Pointing time 1 -2 sec. (60 °/s) Acceleration Up to 120°/s 2 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 5 s Typical integration time 10 to 180 s (GRB) Readout noise 8. 5 e- Field of view ASTEP - 05/09/06 25 cm 1. 86 degrees M. Boer, OHP

SWIFT GRBs observed by TAROT Event Tobs after trigger Magnitude GRB 050306 (z = ? ) 90 s R > 17. 5 GRB 050416 (z = 0. 65) 8 h 25 R > 19 GRB 050505 (z = 4. 2) 540 s I = 18. 2 GRB 050525 a (z = 0. 6) 360 s R = 15. 0 GRB 050730 (z = 3. 97) 66 s I = 15. 5 GRB 050803 (z = 0. 42) 61 min R > 19 GRB 050824 (z = 0. 83) 600 s R = 18 GRB 050904 (z = 6. 29) 86 s I = 14. 1 GRB 051211 b (z = ? ) (INTEGRAL) 12 s R = 16. 2 GRB 051221 (z = ? ) 281 s R > 18 GRB 060111 b (z = ? ) 28 s R = 13. 2 GRB 060124 (z = 2, 30) 7198 s R > 18. 5 26. 8 s R > 19. 5 23. 1 s R = 15. 8 GRB 060717 GRB 060904 A ASTEP - 05/09/06 M. Boer, GRB 060904 B (z = 0. 703) OHP

GRB 050904 • Event at 01: 51: 44 • T 90 = 225 s • First image at 01: 53: 10 (TAROT reaction time 4 s) 86 s after event started • Last at 1666 s • 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 (1054 erg) comparable to GRB 990123 (2. 4 x 1054 erg) • 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, 1 s, 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 60 s, i. e. 18 pixels of continuous monitoring – Following images are nontrailed (sidereal tracking on), 30 to 180 s, 5 s deadtime – For GRB 060111 b, USNO star used as comparison ASTEP - 05/09/06 M. Boer, OHP

The light curve • GRB 060111 b – 20: 15: 43 UT – Close to the Moon – No redshift available but • • UVOT detection (5 min), z < 3 B&G relation gives z = 2, but invalid if z < 0. 5 – Continuous monitoring from 28 to 88 s – From 28 to 61, sampling = 1 px = 3. 33 s, after binning over 4 pix = 13. 3 s • Smooth! – Continuous, fast decay from Ttrig + 28 to 90 s: 2. 4 – No evidence of flare at time of gammaray second peak – Then shallower decay 1. 12, typical AG – If 1 component, Tbreak = 80 s – If 2 component: • • • Alpha 1 = 3. 0 Alpha 2 = 0. 89 Ttrans = 65 s ! 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. 50 m followup 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 - 05/09/06 M. Boer, OHP