Scientific program

Gamma-Ray Bursts

The main goal of TAROT is to be always ready to react to a GCN (Gamma-ray burst Coordinates Network) alert. GCN alerts are provided by satellites devoted to GRB (Gamma-Ray Bursts) detection at high energies.

In optical wavelengths, we distinguish the prompt phase (stage when the emission of high energy photons occurs) , when the GRB is still active in gamma rays, and the afterglow phase ( soft emission provided after the prompt phase ), corresponding to the late emissions. TAROT is specialized to the prompt phase observations in optical wavelengths.

Main results came from TAROT

GRB 050904

The very optical bright emission during the prompt phase of the faster known GRB 050904 at z=6.3. TAROT was the only telescope that recorded the early optical emission of this burst. This is the second brightest optical emission known concerning GRBs. One interpretation is the signature of the reverse shock in the theory of the fireball. But other interpretations remain possible (see papers related to this burst).

Red dots are optical flux measured by TAROT. Black dots are fluxes measured by Swift-XRT in X rays.

GRB 060111B

The continuous optical follow-up during the prompt phase of the GRB 060111B. For the first time in the optical follow-up of GRBs, TAROT success to record continuously the optical emission of a burst during the prompt phase. This is important because many flux fluctuations occur in high energy whereas the TAROT observations show smooth decay in optical wavelengths, This observation can be explained by theory of the reverse shock.

Black dots are TAROT data (excepted the last one from MITSuME experiment). Gray curve is the Swift BAT/XRT fluxes (2-10 keV). There is no correlation between optical and high energy fluxes during the prompt phase (until 70s) that favors the reverse shock models.

Discovery of new variable stars

Each TAROT image is measured by the Sextractor software that extract all sources. These sources are gathered in a huge database where variable stars are automatically recognized. Many hundred of such new variable stars are found (TSVSC1 catalog).

The RR Lyrae stars

Among pulsating stars, RR Lyrae are known to have variations of their periods. TAROT is used to determine the date of maxima of brightness of these stars. Variations of periods of few dozen of stars have been discovered and characterized by TAROT.

Minor planets

TAROT is used to confirm binary asteroids that exhibit eclipses. Moreover, TAROT monitor the stars predicted to be occulted by asteroids ( Observation manage by euraster). This program allows to determine diameters and shapes of minor planets. All observation here.

Negative occultation by Photographica at around 2003-12-25T20:37:58.080
Positive occultation by Wallia at around 2004-04-23T23:24:56

Supernovae

Each image taken by TAROT is croped to extract sub-images centered of known nearby galaxies (z<0.03). Then, sub-images are visually controlled to find new supernovae.

Supernova 2004et prediscovered by TAROT