Télescopes à Action Rapide
pour les Objets Transitoires
This page gives useful informations about the
TAROT observatories and their scientific programs.
For an image gallery click here
1. Description of TAROT observatories
1.1. Current status
TAROT are robotic observatories that observe with no human interaction.
TAROT are two identical 25 cm telescopes F/D=3.4 that cover 1.86°x1.86°
field of view on the Andor CCD cameras (Marconi 4240 back illuminated).
Spatial sampling is 3.3 arcsec/pix. Six filters are available : BVRI, a clear
filter and a 2.7 density coupled to V (for Moon and planets). Detection limit
is about V=17 in 1 min. exposure. Locations of telescopes are:
The princpal investigator of these intruments is Michel Boër (Observatoire
de Haute Provence, 04870 Saint Michel l'Observatoire, France). Two co-investigators
are Jean-Luc Atteia and Alain Klotz, astronomers at the Observatoire Midi
Pyrénées, Toulouse, France. We have collaborations with Yassine
Damerdji, Myrtille Laas-Bourez, Christian Pollas, Raoul Berhend, Alessandra
Corsi, Alessandra Galli, Eric Frappa, Bruce Gendre, Jean-François Leborgne,
Frédéric Malacrino, Luigi Piro, Giullia Stratta.
- TAROT Calern observatory : lon=6.9238° E lat=43.7522°
N alt=1270 m
- TAROT La Silla ESO observatory : lon=70.7322° W lat=29.2608°
S alt=2347 m
Observation requests are send by observers through an internet interface
or by the Gamma-ray Coordinates Network (GCN) through a socket. Planning
is computed each time a new request is received. Telescope slewing is very
fast, up to 60°/second, and read-out time of CCD cameras is only 5 seconds.
When a GCN alert is received, the delay until the opnening of the shutter
is less than 8 seconds.
Raw images are automatically processed by TCL scripts runned by AudeLA software to
provide reduced data ready use for researcher collaborators via web pages
TAROT are not only used for gamma ray bursts observations. They are also
used by collaborators concerning many other scientifi projects (see Section
2), as well as educational programs.
Each observatory has a reliability higher than 90% and produce about 80
000 images per year. An project of Vitural Observatory archive should be achieved
before end of 2008.
1.2. History of TAROT
- 1995 : first design of a robotic observatory
- 1996 : project starts, financed by CNRS
- 1998 : first light of TAROT at the Calern observatory
- 2003 : updates of TAROT Calern to open observing time to other
observations than GRBs
- 2004 : first optical detection of a GRB
- 2005 : first optical ligh-curve of a GRB afteglow
- 2005 : optical emission detected during the prompt emission of
the farest known GRB at z=6.3
- 2006 : first continuous optical ligh-curve of a GRB during prompt
- 2006 : first light of TAROT at the La Silla observatory
2. Scientific programs with TAROT
All publications can be read in this page.
2.1. Gamma-Ray Bursts
The main goal of TAROT is to be always ready to react to a GCN alert.
GCN alerts are provided by satellites devoted to GRB detection at high
energies. In optical wavelengths, we distinguish the prompt phase, when
the GRB is still active in gamma rays, and the afterglow phase, corresponding
to the late emissions. TAROT is specialized to the prompt phase observations
in optical wavelengths. Two main results came from TAROT:
- The very optical bright emission during the prompt phase of the
farest 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 interprtations 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.
- The continuous optical follow-up during the prompt phase of the
For the first time in the optical follow-up of GRBs, TAROT success to record
contniuously 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.
2.2. 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).
2.2. The RR Lyrae stars
Amongst 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
2.3. Minor planets
TAROT is used to confirm binary asteroids that exhibit eclipses.
Moreover, TAROT monitor the stars predicted
to be occulted by asteroids. This program allows to determine diameters
and shapes of minor planets.
by Photographica at around 2003-12-25T20:37:58.080
by Wallia at around 2004-04-23T23:24:56
Each image taken by TAROT is croped to extract sub-images centered of
known nearby galaxies (z<0.03). Then, sub-images are visually controled
to find new supernovae.
Supernova 2004et prediscovered by TAROT
3. About Gamma-Ray Bursts
3.1. Some milestones
3.2. Some usefull links
- Afterglow : soft emission provided after the prompt phase.
- Alpha : power of flux against time (near -1)
- Beta : power of flux against frequencies
- Break : elbow in the light curve that joins two alpha values
- Flares X : raising of the X emission after prompt emission.
- GRB : Gamma-Ray Burst.
- Hardness : ratio of high/soft energy fluxes.
- LGRB : Long GRBs : The origin of these GRBS is probably Wolf Rayet
stars that end into hypernovae.
- Prompt emission : stage when the emission of high energy photons
- Rebrightening : anomalous behaviour of the light curve against
a power law of time.
- SHGRB : Short hard GRBs. These are GRB with t90 < 0.2s. The
origin of these GRBs is probably the merging between two neutron stars.
- t90 : duration between 5% and 95% of the high energy (gamma) emitted.