TAROT (Télescope à Action Rapide pour les Objets Transitoires)

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)


Le modèle de la boule de feu

106 cm

t-1

1016 cm

1013 cm

taft

Emission rémanente

RB

tGRB


Une chaîne pour la détection

8s

0,5s

HETE

position

Pointageobservation(1s)

INTERNET

VHF


Tarot today


A fully automated telescope


Data processing (see A. Klotz)Automated correlation with USNO catalogAutomated image comparison for variable objects


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


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


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


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


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


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 !


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)


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)


TAROT variable star catalog

(Damerdji, Klotz and Boër, 2006)


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


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

Documents

TAROT (Télescope à Action Rapide pour les Objets Transitoires)