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8 november 2011: Asteroid 2005 YU55 came very close to Earth!
2005 YU55 came in the night of November 8 to 319 000 km of the Earth's surface, less than the distance from Earth to the Moon. Its speed is estimated to 46 600 km / h. This asteroid is on an orbit that passes at regular intervals in the vicinity of Earth, Venus and Mars. But Tuesday, it did the closer approach to our planet for at least 200 years. The next time an asteroid as big should come within a distance comparable to the Earth will be in 2028. Radar images show a spherical body 400m diameter. One of our objectives with TRAPPIST beeing the study of small solar system bodies, we joined an international observing campaign to characterize this body. We were able to follow the asteroid for several hours during this close encounter at high speed and take hundreds of images. The image shows the asteroid in the center of the field. The exposure time is 10s, and the telescope is traching the asteroid, so the stars are trailed.	Near Earth asteroid 2005 YU55
27 october 2011: Eris, unveiled by TRAPPIST telescope
This is a unique event that we had the opportunity to observe November 6, 2010 with our robotic telescope, TRAPPIST, installed at the La Silla Observatory in Chile. The dwarf planet Eris, the body most distant in the solar system, located 14 billion km from the Sun or three times farther than Pluto, fell right in front of a star whose brightness went off for about thirty seconds (news 06 Nov 2010). Unlikely event, this stellar occultation, also observed from another site in northern Chile was used to measure the size of the distant planet with unprecedented accuracy (1163 +-6km radius). This result is published today in the journal Nature (Sicardy et al. 2011). Eris is spherical and finally the same size as Pluto (1150-1200 km) and not bigger as astronomers beleived since its discovery (which led to the demotion of Pluto as a planet in 2006). Eris density has been revised upwards: it is a small rocky planet (85%) and not a Panet made of ice like Pluto. This has implications to understand the formation of the solar system. Finally, the surface of Eris has an albedo of 96% which is one of the most reflective in the the solar system! While similar to Pluton about the surface composition, Eris has no atmosphere. It has most probably making it looking like a mirror.	credit/ESO
Paper in Nature : http://www.nature.com/nature/journal/v478/n7370/full/nature10550.html#f2 ESO Press Release : http://www.eso.org/public/belgium-fr/news/eso1142/ Paper published sur le site Réflexions from the Liège University : http://reflexions.ulg.ac.be/cms/c_39797/eris-la-lointaine-jumelle-de-pluton Sky & Telescope : http://www.skyandtelescope.com/news/Eris-and-Pluto-Does-Size-Matter-132755658.html
23 august 2011: Replacement of the dome track (18-31 August 2011)
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7 June 2011: The double occultation of Pluto and Charon of June 4, 2011
This June 4, 2011, the TRAPPIST team did a unique and very difficult observation ! We managed to observe the dwarf planet Pluto and its moon Charon passing in front of a very faint star. The observations were performed remotely from Belgium by E. Jehin using TRAPPIST, a 0.6m robotic telescope installed in 2010 at the La Silla Observatory in Chile. Charon was the first to hide the star for about 50 seconds at 5:30 UT, and about 12 minutes later, Pluto masked the same star during 2 minutes. The light curve of high quality (see figure below) shows the two events and reveals the striking difference between a body with an atmosphere (Pluto) and without atmosphere (Charon). Pluto's atmosphere is actually detected up to an altitude of several hundreds of km from the surface of Pluto. It is the first time a double occultation is observed from a single location. The phenomenon has been observed in two other sites in South America (at the SPACE observatory located in San Pedro de Atacama in Chile and at the observatory "Pico del Dias" in Brazil). These observations are part of an international campaign led by a team from Paris Observatory (Sicardy et al.). The comparison of these various data sets will provide valuable information on the parameters of the orbit of Charon, the size of each object and the atmosphere of Pluto. TRAPPIST had already succeded on Nov. 6, 2011, to observe the first occultation ever recorded of the dwarf planet Eris (E.Jehin et al. IAUC 9184; Sicardy et al 2011, submitted to Nature). Light curve of the occulted star (red) showing two drops of flux. The first, with a square box shape, is due to the satellite Charon, whose size is estimated to about 1200 km. The second, twice as long, is due to Pluto that has a diameter of approximately 2350 km. The curved shape of this occultation reveals the presence of Pluto's atmosphere which refracts the light from the occulted star. The blue curves are the reference stars and are used to control the transparency of the sky which was excellent.
15 April 2011: Two new asteroids discovered by students at the University of Liège
As part of an astronomy course on small solar system bodies (comets and asteroids), given by E.Jehin for the Master is astrophysics of ULg, students from the University of Liège discovered two new asteroids. It was in the lab using the robotic telescope TRAPPIST, located in Chile, that this discovery was made. After having followed several nights and hainge calculated their orbits, these asteroids were confirmed by the International Astronomical Union.. They were given provisional names K11FE9A (or 2011 FA149) and K11FE9B (or 2011 FB149). Both asteroids are in the main asteroid belt between Mars and Jupiter. The first measures a mere 1 km in diameter and the second could be as large as 4 or 5 km. They rotate respectively in 4.2 years and 5.6 years around the Sun at average distances of our star of 390 and 470 million km. Before a final name will be given they must be observed again in the coming years when they will come again in opposition with the Sun. Congratulations to Valentin Christiaens, Marc Levesque, Cyrielle Opitom, Laetitia Delrez, Lorraine Braibant and Emilie Gloesener.	The images of the discovery of the asteroid K11FE9A on March 31. We can see his movement among the stars during this sequence of images of 20 minutes.
16 March 2011: First participation of TRAPPIST to the detection of an exoplanet
TRAPPIST has contributed to the detection of the exoplanet WASP-23b. This planet is a gas giant very similar in size and mass to Jupiter. It orbits at less than 0.04 astronomical units of its host star, a dwarf star cooler and smaller than the Sun located about 600 light-years in the austral Puppis constellation. The TRAPPIST data have confirmed the existence of the planet, first detected by the WASP survey, and were used to measure precisely its size. For more details, see http://arxiv.org/abs/1103.2603	Transit of the WASP-23b exoplanet (Triaud et al. 2011)
14 February 2011: TRAPPIST observatory code is I40
Today the Minor Planet Center attributed the observatory code I40 to TRAPPIST !
2 February 2011: TRAPPIST recovers comet 9P/Tempel 1
This tiny fuzzy spike of light, lost in a rich field of the Milky Way and 10000 times fainter than the faintest stars visible to the naked eye, is periodic comet 9P/Tempel 1. This comet was the target of the NASA Deep Impact mission in 2005 which dropped a 500 kg copper bullet on its nucleus in order to study the material released by the blast. About 6 years later, on February 14, the 9P ~5km nucleus will be revisited by the Stardust Spacecraft that collected several years ago dust grains in the tail of comet 81P/Wild 2. A similar story happened a couple of months ago with the Deep Impact spacecraft itself that has also been rerouted to fly above the comet 103P/Hartley2 nucleus on November 4, providing spectacular images. One of the goal of the new mission of the Stardust spacecraft will be to take pictures of the crater, not seen yet, formed by the 2005 Deep Impact. Currently at 2.6 AU from the Earth and lost in the glare of the rising Sun, these images of the comet have been taken by the new belgian telescope based in la Silla Observatory (Chile).	Comet 9P/Tempel 1 moving among the stars
21 December 2010: The asteroid that wanted to be a comet
On December 11, asteroid (596) Scheila was discovered to have a small coma like a comet. There is a claim since a few years that comets are hiding in the main asteroid belt . Those so-called Main Belt Comets (MBC) would in fact be a newly discovered population of comets that formed in the outer edge of the Main Asteroid Belt. A few of them have been discovered and there could be thousands of them but still to discover. They are difficult to find because they are very weakly active. There is also the recent observation that big asteroid Themis has ices on its surface. These observations are very interesting because they show that comets and asteroids might not be exactly like we think and there might be more links between them than we thought before. Is asteroid Scheila a MBC ? A very important observation to decide would be to discover if there is gas in its coma. Indeed comet activity is triggered by the sublimation of water and other ices like CO an CO2 by the Sun light. So far none of the MBC have been observed to have gas and some people claim that those objects are in fact activated asteroids for instance after a collision with a smaller asteroid. We have been observing Scheila for a week with TRAPPIST using our narrow band filters and no gaseous species has been detected ! This is confirmed from deep spectra taken by our team at the ESO Very Large Telescope and still to be published. Scheila, like the object P/2010 A2 observed earlier this year, does not seem to be a comet. The coma is most probably rather resulting from an asteroid-on-asteroid impact. The coma is indeed vanishing in space from day to day and there is no sustain activity. Stay tune for more information ! (596) Scheila http://adsabs.harvard.edu/abs/2011CBET.2632....2J Jehin, E.; Manfroid, J.; Hutsemekers, D.; Gillon, M.; Magain, P.	Asteroid Scheila surrounded by a dust cloud
6 November 2010: TRAPPIST and dwarf planet Eris
A first was achieved on the night of November 6 with TRAPPIST ! Emmanuël Jehin became the first astronomer to observe a stellar occultation by the dwarf planet Eris. This planet occulted a 15 magnitude star for a period of 30 seconds. This unlikely observation, combined with that also carried out in San Pedro de Atacama by Alain Maury and his team, will enable the size of Eris to be measured to within a few dozen kilometres or so. Up until now its size was only known within a range of some hundreds of kilometres! The observation of this occultation is the longest ever to have been carried out: a distance of 14 billion kilometres (three times as far as Pluto). Emmanuël Jehin & others / TRAPPIST Observatory http://www.skyandtelescope.com/news/106861063.html E. Jehin, J. Manfroid, M. Gillon, D. Hutsemekers, and P. Magain, ?Occultation by (136169) Eris?, 2010 IAUC 9184.	Images taken every 4,5 seconds clearly show the brief disappearance of a star behind the dwarf planet Eris on November 6, 2010 (Universal Time).
4 November 2010: Comet Hartley2 observing campaign
TRAPPIST is part of an international observing campaign to observe the Jupiter Family comet 103P/Hartley 2 that has just been flew by the NASA EPOXI spacecraft today. Spectacular images have been sent to Earth by EPOXI showing strong jets coming from a very small (2km) pinut shape nucleus. The many TRAPPIST observations through special filters that are collected every day during this period are used to derive the composition of the comet and to follow its activity. A rotation period of the nulecus of 18.2 hours has been found as well as a braking of the rotation speed with time. Jehin, E.; Manfroid, J.; Hutsemekers, D.; Gillon, M.; Magain, P, "Comet 103P/Hartley", 2010 CBET 2589 http://www.nasa.gov/mission_pages/epoxi/epoxi20101104b.html	Comet 103P/Hartley2 on Oct. 31 through the various narrow band cometary filters (from left to right the images reveal the distribution of the radicals OH, CN, C3, C2, GC and the ion H2O+)
8 June 2010: TRAPPIST First Light !
Our new robotic telescope has had its first light at the European Southern Observatory's (ESO) La Silla Observatory in Chile last night. The TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST) is devoted to the study of planetary systems through two approaches: the detection and characterization of planets located outside the solar system (exoplanets), and the study of comets orbiting around the Sun. It is a 24-inch (60 centimeters) robotic telescope which is operated from a control room in Liege, Belgium, 12,000 kilometers away. The first light was done from the Liège University downtown with Bernard Rentier the rector of the University, Didier Queloz from Geneva Observatory, the TRAPPIST team and journalists. Control of the telescope was taken and the first light has been done on the famous Tarentula Nebula in real time. http://www.ulg.ac.be/cms/c_470567/trappist-va-brasser-le-ciel http://www.eso.org/public/news/eso1023/	TRAPPIST first light image of the Tarantula Nebula in the Large Magellanic Cloud.

Contact: trappist@astro.ulg.ac.be