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LJMU scientists announce the arrival of SPRAT, an exciting new instrument on the Liverpool Telescope 1600 GMT 5 September 2014
SPRAT photo SPRAT mounted on the Liverpool Telescope on La Palma.

Astronomers from the Astrophysics Research Institute (ARI) of Liverpool John Moores University recently announced the successful commissioning of an exciting new instrument on the Liverpool Telescope to colleagues and collaborators at an international conference in Poland. The conference, which was held in Warsaw in early September, brought together researchers from across Europe who are interested in observing variables and "transients" - objects that vary in brightness suddenly and dramatically. The meeting focused on objects that will be discovered with the GAIA space telescope, an ESA mission that was launched late last year. The LT will undoubtedly be a key player in this area of astronomical research.

Affectionately known as SPRAT, the SPectrometer for the Rapid Acquisition of Transients will provide astronomers from LJMU, the rest of the UK, and overseas with the opportunity to rapidly observe and analyse the light from all manner of variable objects. SPRAT will be particularly useful for studying novae and type Ia supernovae - stars in binary systems that undergo sudden outbursts - and core-collapse supernovae, massive stars that at the end of their lives collapse under their own weight causing a massive explosion of light and energy. Both areas of research are of particular interest to astronomers at the ARI.

SPRAT drawing A technical drawing showing the internal layout of SPRAT.
SPRAT spectrum Two first-light spectra of supernova ASASSN 14gh obtained with SPRAT during commissioning on Thursday, 4 September, 2014 (target courtesy D. Bersier/LJMU). The red and blue spectra show how the instrument may be optimised for observations at long or short optical wavelengths, respectively. The target itself was recently discovered by ASAS-SN, the All-Sky Automated Survey for Supernovae.

SPRAT was designed and built entirely by LJMU scientists and engineers subsidised mainly by internal LJMU funding. The instrument, the brainchild of Prof. Iain Steele, the Director of the Liverpool Telescope, was taken to La Palma in the Canary Islands on 30th August by a team from LJMU comprising Stuart Bates, Robert Smith and Andrzej Piascik. Joined by fourth team member Dirk Raback they spent the first week in September mounting the instrument on the telescope and carefully characterising it, in preparation for robotic use later in the month.

Andrzej, a PhD student at LJMU, has spent the last twelve months fine-tuning the performance of SPRAT in an optical lab in Liverpool Science Park (where the LT group is based). He joined the team on site and will present the instrument to the community at the Warsaw Conference. Meanwhile, testing will continue from Liverpool: software engineers Neil Clay, Chris Mottram and Steve Fraser will ensure that the instrument can be controlled remotely and robotically, that is, by the complex control system used to operate the telescope. Mike Tomlinson will provide IT support, while astronomers Jon Marchant, Rob Barnsley and Chris Davis will ensure that the data obtained are suitable for scientific use.

The commissioning of SPRAT brings the instrument suite on the LT to a grand total of six; a seventh instrument, the IO:I near-infrared imager, is currently being developed and will hopefully be commissioned later this year. In the meantime, SPRAT will undoubtedly prove to be an invaluable tool to a wide range of researchers in transient and time-domain astronomy.

SPRAT PN spectrum A false-colour SPRAT "spectral image" of a planetary nebula (PN), taken shortly after commissioning of the instrument by LT astronomer Robert Smith. The nebula is seen in emission from different atoms; the core of the dying star is seen as a horizontal strip of continuum emission.
RAS specialist discussion meeting on time domain astronomy with LT and LT2 1600 GMT 15 August 2014

Researchers in transient and time domain astronomy are invited to attend a Royal Astronomical Society (RAS) Specialist Discussion Meeting in London on Friday, 14 November. The discussion will focus on astronomy and astrophysics with the Liverpool Telescope and Liverpool Telescope 2. The aims of the meeting are to showcase the many varied programmes that are active on the Liverpool Telescope, to stimulate new collaborations and ideas, and to engage with the community regarding our plans for the future.

lsst An artists impression of what the Large Synoptic Survey Telescope (LSST) will look like on Cerro Pachon in Chile. Image courtesy NOAO.

The robotic 2m Liverpool Telescope, based on the Canary Island of La Palma, is owned and operated by Liverpool John Moores University, with operational support from STFC. It has a strong track record of service to the time domain community in the UK and beyond. The next decade will see time domain science becoming an increasingly prominent part of the astronomical agenda, and the LT will continue to be at the forefront, with large programmes exploiting new transient sources discovered with facilities such as iPTF, Gaia and LOFAR.

Looking further into the future, the next generation of surveys such as LSST will revolutionise the study of the time variable sky, and facilities such as CTA will probe transient phenomena at previously unexplored wavelengths. New exoplanet finders, starting with NGTS and followed by the next generation of space missions, will improve on the Kepler Space Telescope's efforts by discovering more planets orbiting bright host stars in order to maximise the potential of ground based follow-up. In addition, the anticipated discoveries of electromagnetic counterparts to astrophysical gravitational wave and neutrino sources will open new windows on the transient universe.

There will be a pressing need for follow-up facilities for scientific exploitation, in particular spectroscopic follow-up. With that in mind, plans are underway for Liverpool Telescope 2, a new 4-metre robotic telescope to be built on La Palma, with a world-leading response time for follow-up of the most rapidly varying objects.

cta The Cherenkov Telescope Array (CTA) will be a new facility for ground-based gamma-ray astronomy in the energy regime from 10 GeV to a few hundred TeV. Image courtesy University of Heidelberg.

An overview of the current status of the Liverpool Telescope 2 project is provided in a recent SPIE article (Copperwheat et al. 2014). A detailed science white paper will also shortly be made available on the astrophysics archive and on the LT2 website. In the meeting we will discuss the scientific role for LT2, focusing largely (though not exclusively) on the objectives outlined in these documents. We will also discuss the instrumental requirements for LT2, as well as potential enhancements to LT to enable it to remain relevant in the 2020 time domain landscape.

Time and location of the meeting

The meeting will be held at the Royal Astronomical Society, Burlington House, London, on 14 November, 2014. A more detailed agenda of talks will be circulated in due course.

Registration and abstracts

Attendance at this meeting is free for members of the RAS. For non-members there will be an attendance fee of £15 (£5 for students) to be paid at the door. The deadline for the submission of abstracts is 7 October 2014. Abstracts should be sent to Chris Copperwheat (c.m.copperwheat "at" ljmu.ac.uk) or Chris Davis (c.j.davis "at" ljmu.ac.uk).

Science Organising Committee:
Mike Bode, Chris Copperwheat, Chris Davis & Iain Steele

For further information on the Liverpool Telescope 2 project, please visit the LT2 web-site.

Research Council confirms future Liverpool Telescope Operations funding 1600 GMT 6 Aug 2014
LT staff An all-sky view, taken by skycam-A earlier this year, showing the La Palma summit horizon, the Liverpool Telescope, a glorious night sky, a fireball, and the William Herschel Telescope laser! Hundreds of images like these are obtained every night by our three wide-field imagers, SkyCameras A, T and Z. These images are posted on the LT Live Status webpage, with the constellations and other astronomical objects conveniently labelled, within minutes of being observed. Movies constructed from these images showing the motion of the heavens above the summit are posted on our Night reports web page the following morning.

The Liverpool Telescope is delighted to announce confirmation of receipt of a grant for £250,000 per year from the U.K. Science and Technology Facilities Council (STFC). This grant will support the operation of the LT over the next two years initially (staring 1 October 2014) as part of a five year Business Plan recently endorsed by the STFC's LT Oversight Committee. The funding ensures continuing access to the telescope for a wide range of astronomers and astrophysicists from Universities and Institutes across the UK and internationally.

The LT is currently experiencing a period of rapid growth; in terms of instrument development, but also interest from its user base. Demand for telescope time from British astronomers has doubled in recent years, and continues to be similarly high from our Spanish colleagues and, indeed, from internal Liverpool John Moores University users.

LJMU's Astrophysics Research Institute and other users of the telescope are about to embark on an ambitious and exciting few years of research at the forefront of time domain astronomy, facilitated by the commissioning of two new instruments - the infrared arm of the optical-infrared imager IO, and a high-throughput SPectrometer for the Rapid Acquisition of Transients, SPRAT. IO:I will enable near-simultaneous monitoring of all manner of transients and variables in the optical and near-infrared bands. SPRAT, on the other hand, will allow for spectral classification of much fainter targets than was previously possible (down to approximately 20th magnitude) in just a few minutes. SPRAT should, for example, be a boon for researchers trying to understand the physics and chemistry of exploding stars such as novae and supernovae before these objects fade from view.

Our expectation is that both instruments will be commissioned over the next few months, ready for use by observers towards the end of this year. In all, six instruments will be available on any given night, providing imaging, spectroscopic, and polarimetric capabilities. With the recently approved funding, these instruments are now sure to be available for exploitation by astronomers in the UK and internationally for a number of years to come.

For details on how and when to apply for telescope time on the Liverpool Telescope, please consult the LT Phase 1 webpage. If you have any questions are comments about access to the LT, please don't hesitate to contact us. Our contact details are available here.

Rapid-response monitoring of a "nearby monster" 1500 GMT 17 June 2014
Light curve Above: X-ray, Ultraviolet (w2, m2, w1 filters) and visible (B,V,u,b,v,g',r',i') light curves showing the declining brightness of GRB 130427A over a period of a few weeks. In this plot LT and Faulkes-North r' and i'-band data points are coloured red and yellow. The discovery was triggered in the X-ray (black data points). [Full size image]

On April 27, 2013 many of the world's astronomers observed the brightest Gamma-Ray Burst (GRB) ever detected by the Swift satellite. Named GRB 130427A, it was one of the most energetic nearby events ever encountered. At a redshift of z = 0.3399, which corresponds to a distance of only 3.6 billion light years, GRB 130427A was a truly unique and extraordinary "nearby monster".

GRBs trace the most energetic explosions in the Universe. Some are believed to occur after the merger of two compact objects - a pair of neutron stars or a neutron star and a black hole. Others may be caused by the collapse of a rapidly-rotating massive star. The former are classified as short-GRBs, due to the very limited durations of their gamma-ray emission (less than a few seconds). The latter are classified as long-GRBs, since the mean duration of their "prompt emission" phase lasts longer than a few tens of seconds.

GRB 130427A belongs to the second class of object (its duration lasted longer than 160 sec) and was probably the result of the collapse of a star 30-40 times the mass of the Sun with an intrinsic luminosity of 3 x 1053 erg/sec (for comparison the luminosity of the Sun is a mere 3.8 x 1033 erg/sec, one hundred billion billion times less!).

Ground-based facilities such as the Liverpool Telescope and Faulkes-North (a sister telescope to the LT) were used to monitor the optical behaviour of GRB 130427A, from very soon after the explosion up to relatively late times (see the attached light curves). These monitoring observations tracked the evolution of the burst emission with a high cadence, from the initial "prompt" phase to the "afterglow" phase (Maselli et al. 2014).

Careful analysis of these multi-wavelength data (which include GeV, Gamma-ray, X-ray, ultra-violet and optical bands) showed that the relatively nearby GRB 130427A had similar properties to the most luminous and much more distant high-redshift GRBs. This result suggests that a common central engine may be responsible for producing GRBs in both the contemporary, nearby universe and in the much more distant, early universe, as well as over the full range of GRB isotropic energies. Moreover, "monsters" like GRB 130427A seem to be strictly connected with Supernovae explosions (GRB 130427A was subsequently found to be associated with SN 2013cq) which, prior to these observations, was observed to be the case for only the weaker long-GRBs (Melandri et al. 2014).

Clearly, with their rapid response capabilities, robotic telescopes like the Liverpool Telescope are crucial to our understanding of the rapid evolution of these remarkable transient objects, both at early times during the prompt/afterglow phase and at later times as the GRB afterglow fades and the SN phase emerges.

Maselli A., Melandri A., Nava L., Mundell C. G., Kawai N. et al. 2014, Science, 343, 48 (link to paper).
Melandri A., Pian E., D'Elia V., D'Avanzo P., Della Valle M. et al. 2014, A&A in press, (arXiv:1404.6654).

Bumps, Burps and Bangs hit this year's National Astronomy Meeting in Portsmouth 1100 GMT 9 May 2014
LT staff Click above for the official NAM website.

The Liverpool Telescope team will once again be leading a session on Time Domain Astronomy at this year's U.K. National Astronomy Meeting. Entitled Bumps, Burps and Bangs - Transient and Time Domain Astronomy in the U.K., the two-block session has attracted the attention of researchers in the field from across the U.K.

In all, 23 abstracts were submitted from which 11 have been selected to give 15 minute talks. These talks will be spread across two sessions on the afternoon of Wednesday, 25th June, starting at 13:30. The presenters are listed below. In addition, poster are expected from 12 groups spanning topics in galactic, extra-galactic and solar system astrophysics.

This year NAM will be held in the historic south-coast town of Portsmouth. The Institute of Cosmology and Gravitation (ICG) at the University of Portsmouth will host the meeting, which runs from 23-26 June. The meeting is targeted at professional astronomers but also includes a programme of public talks and other events aimed at engaging keen amateurs, members of the public, and the press. Registration is, however, required for all: the registration deadline is 30th May 2014.

Oral Presentations
Phil Lucas Univ. Hertfordshire Eruptive Variable YSOs from VVV and UKIDSS GPS
Darryl Sergison Univ. Exeter Untangling the signals: Simultaneous photometry and spectroscopy of YSOs in Orion
Danny Steeghs Univ. Warwick Galactic transients from accreting white dwarfs
Steven Williams   Liverpool John Moores Univ.   A Significant Proportion of M31 Novae Appear to Contain Red- giant Secondaries  
Matt Darnley Liverpool John Moores Univ. A remarkable recurrent nova in M31
Colin Hill Queens Univ. Belfast Roche tomography of cataclysmic variables - Differential rotation of AE Aqr
Kate Maguire ESO Exploring the diversity of low-redshift Type Ia supernovae using the Palomar Transient Factory  
Sam Connolly Univ. Southampton Long-term wind-driven X-ray spectral variability of Seyfert AGN  
Francisco Virgili   Liverpool John Moores Univ. Gamma-ray bursts with the Liverpool Telescope
Gemma Anderson   Oxford Univ. Rapid radio follow-up of GRBs with the Arcminute Microkelvin Imager
Chris Davis Liverpool John Moores Univ. The future of time-domain astronomy with Liverpool Telescope 2  

Poster Presentations
Chris Davis Liverpool John Moores Univ. Time Domain Astronomy with the Liverpool Telescope
Christopher Frohmaier Univ. Southampton Volumetric Type Ia supernova rate in the local Universe from PTF
David Starkey Univ. St Andrews Echo Mapping of AGN accretion Disks
Marie Van de Sande   Univ. Southampton Probing flickering variability in cataclysmic variable stars
Georgios Dimitriadis   Univ. Southampton Late time data of PTF Supernovae Type Ia
Marcus Lohr Open Univ. Serendipitous Time-Domain Astronomy: Exploring eclipsing binaries with SuperWASP
Gregory Brown Univ. Warwick Swift J1112.2-8238: A candidate relativistic tidal disruption flare
Adam Stewart Oxford Univ. Discovery of a Short Duration, Low Frequency Radio Transient Candidate at the North Celestial Pole with LOFAR
Helen Jermak Liverpool John Moores Univ.   The RINGO2 Blazar Catalogue
Aidan Glennie Oxford Univ. Fast X-ray transients in Chandra data archive
Ben Gompertz   Univ. Leicester The role of magnetars in short gamma-ray bursts with extended emission
Matt Darnley Liverpool John Moores Univ. Liverpool Telescope Spectroscopic and Photometric Observations of Nova Delphini 2013 (V339 Del)  

LT used to follow the brightest supernovae 0900 GMT 8 May 2014

LT staff Top: An LT image of the super-luminous supernova, PTF12dam. Bottom: A plot showing how the luminosity of PTF12dam varies over time (open circles), compared with models of pair-instability supernovae (PISN) and a magnetar-powered supernova.

Astronomers lead by a team from Queen's University Belfast have recently published new observations which help to constrain the power sources driving the brightest explosions in the Universe, known as "super-luminous" supernovae. Their findings have recently been published in a paper lead by Matt Nicholl in the journal Nature*.

Super-luminous supernovae are 10-100 times brighter than normal supernovae, but are extremely rare. Scientists have proposed several theories as to why these unusual events emit so much light. One long-standing idea is that these supernovae result from an instability (called a "pair-instability") occurring in the most massive stars, objects over 100 times the mass of our Sun. The instabillity generates huge amounts of radioactive material.

Another popular idea is that the additional energy needed to power these supernovae comes from a rapidly rotating, highly magnetic core (a "magnetar"). The more massive the star, the longer it takes for light to escape from the ejected stellar material, resulting in a slower rise to maximum brightness.

One particular super-luminous supernovae, PTF12dam, was seen to evolve very slowly. It was therefore a good candidate for a pair-instability supernova. Nicholl and his team monitored this object for over a year, using the Liverpool Telescope and others around the world. By comparing their data with pair-instability and magnetar models, they found that despite a very slow fade after peak luminosity, PTF12dam brightened too quickly in the early stages to have come from an extremely massive star. However, their analysis showed that a magnetar-powered model could reproduce the observations.

The graph shown to the left shows a comparison between the changing luminosity of the target and four models. The three pair-instability models - the three coloured lines - do not fit the data at all well. They clearly take too long to reach peak brightness, presumably because of a large diffusion mass. The magnetar model, however, indicated by the black curve, fits the data well. In this model the magnetar spins with a period of 2.6 milliseconds, possesses a very strong magnetic field (1014 Gauss), and has ejected 10 solar masses of material.

The Liverpool Telescope is ideally suited for imaging these rare transients, as frequent observations over many days are needed to show how the luminosity varies with time. These and similar observations will continue to provide major clues to unravelling the mysteries of these fascinating supernovae.

* Nicholl M., Smartt S.J., et al. 2014, Slowly fading super-luminous supernovae that are not pair-instability explosions, Nature, 502, 346.

LT used to monitor a remarkable recurrent nova in M31 1200 GMT 28 January 2014
LT staff Background: an IO:O image showing the 2013 outburst of M31N 2008-12a taken on 28th Nov 2013. The white circle shows the position of the nova. The white boxes indicate the position of one of the coincident HST fields. Inset: an HST image of the region surrounding M31N 2008-12a. The green ellipses indicate the search region for the progenitor, and the red cross indicates the position of the progenitor candidate.

In late 2013 another outburst of a rather unusual "recurrent nova (RN)" in the Andromeda galaxy, M31, was announced by the intermediate Palomar Transient Factory (iPTF). Novae are thought to be associated with binary systems which undergo a sudden brightening as material from an evolved secondary star falls (or "accretes") onto a compact primary star, usually a white dwarf. The accreting material ignites via nuclear fusion producing a sudden burst of radiation. Recurrent novae are - as the name suggests - objects which undergo multiple outbursts.

Like other RN, the object in M31, dubbed M31N 2008-12a, has been observed in outburst a number of times in the past. What makes this particular object interesting is its very short "recurrence timescale", i.e. the time between outbursts. M31N 2008-12a outbursts have been recorded almost annually since late 2008, when the object was first identified as a nova. Previously the most frequent RN was the Galactic system U Scorpii, which has a ~10 year inter-outburst time, making M31N 2008-12a all the more remarkable!

LT staff IO:O mounted on the bottom of the Liverpool telescope. The gold cylinder is the dewar that houses the CCD detector, cooled to -110 degrees C; the grey box on the right contains the instrument electronics.

M31N 2008-12a is classed as a "very-fast" nova because it takes just four days for the brightness of the object to decline by two magnitudes. As such, our knowledge of its "lightcurve" (a graph showing how the object's brightness changes with time) is limited, even after five outbursts have been witnessed. Follow-up observations of the RN - something the LT does extremely well - were clearly needed.

Following the 2013 outburst, Dr Matt Darnley of the Astrophysics Research Institute here at Liverpool John Moores University formed a collaboration with Dr Martin Henze of the European Space Astronomy Centre in Spain. Their goal was to investigate ground-based optical plus space-based Swift X-ray and UV observations of the outburst, as well as Hubble Space Telescope (HST) infra-red, optical and UV observations of the "progenitor" system, i.e. the system before an outburst occurred. The collaboration also included LJMU's Steven Williams and Prof. Mike Bode.

A Liverpool Telescope IO:O image of the 2013 outburst, shown on the right, was used to precisely determine the position of the nova so that a search for a progenitor could be made. Archival HST observations - taken when the system was not in outburst - indicated the presence of a system coincident with the outburst position. This progenitor is consistent with a binary system known to contain an evolved secondary star (a sub-giant or red giant) and a luminous accretion disk. Such a bright disk indicates a high accretion rate, which is required for a system with such a short recurrence timescale.

An X-ray plus UV monitoring campaign undertaken with the Swift satellite soon after the 2013 outburst clearly detected a bright X-ray source only six days after the optical discovery. Such X-ray emission can only be detected when the nuclear burning on the surface of the white dwarf is viewed directly. The X-ray source persisted for two weeks before "turning-off", indicating the end of the nuclear burning phase. From these and other supporting observations Darnley et al. were able to identify the primary as a very high mass white dwarf.

Such a system - containing an evolved secondary star, a high mass white dwarf star, and a luminous accretion disk - coupled with a short recurrence time, is a prime candidate for a system that may one day become a "Type Ia supernova". SN Ia can be used to accurately measure the distances to very distant galaxies, and thereby map the expansion (and indeed the acceleration!) of the universe. As such our understanding of Type Ia supernova is of considerable importance. With its one-year outburst timescale, the team will be eagerly monitoring M31N 2008-12a with the LT and with other facilities over the next 12 months to see what happens next with this remarkable object.

Black Hole discovered orbiting a Spinning Star 1200 GMT 20 January 2014

A group of Spanish astronomers using the Liverpool and Mercator Telescopes at the Observatorio del Roque de los Muchachos have recently reported the discovery of a binary star system comprising a Be-type star and, remarkably, a black hole.

LT staff Artists impression of a Be star spinning at extreme velocities and depositing matter onto its binary companion, a black hole, seen here in the background.
Image credit: Gabriel Perez - SMM (IAC).

Jorge Casares of the Instituto de Astrofisica de Canarias (IAC) and La Laguna University (ULL) is lead author on a paper1, recently published in the science journal Nature, in which he and his colleagues present their exciting results.

Be-type stars are known to be fast rotators, and many find themselves to be one-half of an interacting binary system. However, their companions are usually neutron stars. This is the first time that the object orbiting the Be star has been identified as a black hole.

The newly-discovered system is located in the constellation Lacerta (the Lizard), at a distance of about 8,500 light years from the Earth. Known as MWC 656, the Be star rotates with an angular velocity of more than 1 million kilometres per hour. At this speed the star is close to being ripped apart by centrifugal forces, and is ejecting matter through an equatorial disk towards its mysterious companion. Casares' new spectroscopic observations indicate that this companion is a black hole.

A detailed analysis of the spectrum of MWC 656 suggests that its companion has a mass somewhere between 3.8 and 6.9 times that of the sun. Such an object is too massive to be a neutron star, and can only be a black hole. Matter is transferred from the Be star, though its equatorial disk, down onto the black hole via a second disk (an "accretion disk"). By analysing the emission from this second disk Casares and his team were able to measure the mass of the black hole.

In all likelihood, binary systems comprising Be-type stars and black holes are far more common than previously thought. Even so, it is notable that such a discovery was made using two relatively modest-sized telescopes, the 2.0 meter LT and the 1.2 meter Mercator telescope.

1Casares J., Negueruela I., Ribo M., Ribas I., Paredes J.M., Herrero A., Simon-Diaz S., 2014, Nature, 505, 378 [links: Nature | Astro-ph ].

Spectroscopic observations obtained with FRODOspec on the Liverpool Telescope showing the orbital evolution of emission lines from ionised Iron (Fe) and ionised Helium (He) atoms: (a) a sequence of spectra showing the change in line profile shape through one orbital phase; the vertical dashed line indicates the rest wavelength of each transition. (b) trailed intensity images of the same two emission lines plotted across two orbital cycles. See paper [ Nature | Astro-ph ] for further details.
LT's GAIA tracking featured on the BBC's Northwest Tonight news show 1200 GMT 13 January 2014
LT staff
LT staff LJMU staff explaining the role the LT will play in tracking GAIA. Still from the show courtesy of BBC Television.

As part of the BBC's Stargazing Live 2014 series of events, the Liverpool Telescope featured recently on the Northwest Tonight news programme. LT staff and scientists from the Astrophysics Research Institute at Liverpool John Moores University explained how the telescope is being used to track the recently-launched GAIA satellite.

GAIA is a major ESA space telescope which aims at obtaining a 3-dimensional map of large chunks of the Milky Way. To do this, the position of the satellite must be known precisely. Telescopes like the LT are thus conducting nightly observations of the satellite, which will observe from a gravitationally stable point in space called 'L2'. At a distance of 1.5 million km from Earth, L2 lies on the axis that links the Earth to the Sun, and is in fact in the shadow of the Earth. GAIA will therefore orbit this point so that sunlight can be used to provide power to the satellite.

Launch of the GAIA satellite from ESA's Spaceport in Kourou, French Guiana. Image credit: ESA - S. Corvaja, 2013.

GAIA will measure the positions and velocities of about one billion stars - that's about 1% of all stars in the Milky Way. With these data astronomers should be able to probe the composition, formation and evolution of our Galaxy. GAIA should also reveal thousands of variable and transient phenomena, since it will re-observe large sections of sky every few days.

GAIA will observe the Milky Way for at least five years. Monitoring the position of GAIA is just one of many nightly duties conducted robotically by the LT. It is, however, arguably one of its most important.