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LT tracks rare microlensed quasar 18 October 2016

In a paper entitled "Gravitational lens system SDSS J1339+1310: microlensing factory and time delay" currently in preprint at arXiv , authors Luis Julian Goicoechea Santamaria and Vyacheslav Shalyapin reveal how the Liverpool Telescope (LT) has been used to characterise a gravitational lens created by a foreground galaxy in direct line with a much more distant quasar.

Light from quasar is bent by intervening galaxy's gravity, causing double image (A & B) at Earth. Quasar image inset is real LT data.
© 2016 LT group.

Light from the quasar that is heading in the general direction of Earth is passing either side of the foreground galaxy, and is being bent by the galaxy's gravity to meet at a focus at the Solar System.

From Earth we therefore see two images of the quasar, but because each light path takes a slightly different route around the galaxy, one longer than the other, the images are out of sync. Therefore any disturbance or variation in brightness from the quasar will be seen first in one image, and then repeated after some delay in the other image.

The LT data has not only revealed the time delay between both images, and also that the lensing galaxy is causing microlensing with its constituent stars along the light paths from the quasar.

Since 2005, the Gravitational LENses and DArk MAtter (GLENDAMA) team has been conducting optical monitoring of about 10 gravitationally lensed quasars with the LT. For each target, the main goals are to measure time delays between the multiple quasar images, as well as analyse the intrinsic variability of the lensed source and the possible flux variations caused by microlenses (stars) in the lensing galaxy.

After an 8-year monitoring campaign of the double quasar SDSS J1339+1310 in SDSS-R band, the LT light curves of its two images, A and B, are characterised by typical photometric accuracies of 1-2% and an average sampling rate of once every 6 days (excluding gaps).

Lightcurve of quasar images A & B from 2009-2016 (dates along top axis).
From paper by Goicoechea and Shalyapin (2016).

These light curves show parallel V-shaped variations, which allowed the GLENDAMA team to determine a time delay of 47 days with 10% precision.

In addition, the accurate follow-up observations of both images reveal the presence of significant microlensing-induced flux variations on different timescales, including rapid microlensing events lasting 50-100 days.

While the strong microlensing activity precludes a more accurate estimation of the delay between A and B, the rapid events are very rare phenomena, and thus unique tools for astrophysical studies.

Optical spectra taken with the Gran Telescopio Canarias (GTC) confirm that the system SDSS J1339+1310 is an unusual “microlensing factory”, since appreciable microlensing-induced spectral distortions are also detected.

The paper was accepted in September 2016 for publication in the journal Astronomy & Astrophysics, and is expected to be published soon.

Liverpool Telescope seeking new members for user group committee 10 October 2016
The Liverpool Telescope
The Liverpool Telescope © 2006 R. Smith

We seek expressions of interest from researchers at all career stages with an interest in time­‐domain astronomy and/or active users of the Liverpool Telescope to join the LT User Group (LTUG).

The LTUG is an advisory committee which evaluates and comments upon the day­‐to-day operations of the telescope, the performance of the observatory and its instruments. Key topics for discussion are the productivity of the telescope and maximising the relevance of the science being conducted, the effectiveness of the observatory’s interactions with its user base, and the quality of the user experience. Advice on telescope and instrument modifications and upgrades is also sought.

The LTUG comprises seven members: two drawn from the Astrophysics Research Institute (ARI) at Liverpool John Moores University, and five from the external user community. At least one of these external users should be from the Spanish/CAT community. Each member serves for a maximum of three years. The LTUG meets twice per year, typically via a telecon in Spring and a meeting in Liverpool in Autumn. Travel expenses are provided. You can download the LTUG charter here.

Service on the LTUG provides an opportunity to guide the future direction of this facility, and we would welcome EOIs from interested members of the community. EOIs consisting of a short, paragraph-long CV should be sent to the LTUG chair (Stephen Smartt: s.smartt@qub.ac.uk), and the LT Astronomer-in-charge (Chris Copperwheat: c.m.copperwheat@ljmu.ac.uk).

Iridis: Insight Astronomy Photographer of the Year 2016 24 September 2016
Iridis © 2016 Robert Smith
“This picture tells us that data can be beautiful. It is as compelling visually as it is scientifically, revealing the mechanics of astrophysical knowledge in minimalist yet stunningly attractive way.” - Melanie Vandenbrouck (IAPY judging panel)

JMU employee Robert Smith has claimed a prize in the prestigious international photography competition, the Insight Astronomy Photographer of the Year, with an image obtained from the Liverpool Telescope.

This composite of two images obtained with the Liverpool Telescope compares slit-less spectroscopy of two well known planetary nebulae, NGC6543 (Cat’s Eye Nebula) at the top, and NGC6720 (M57 Ring Nebula) below. In a spectrograph the light is dispersed into its constituent colours. If a target emits light at all wavelengths (such as the star at the centre of each nebula) then it is transformed into a horizontal line and all those colours add up to appear white to our eyes. Planetary nebulae, such as these, only emit light at very specific individual wavelengths. Each of the emission lines creates a separate image in the instrument. A normal image of the nebula is thus decomposed into its individual constituent colours. The particular wavelengths a nebula emits identify the gases of which it consists. Here, the brightest emissions are the red hydrogen-alpha and green oxygen-III lines. The observations were obtained robotically using the Liverpool Telescope and the SPRAT spectrograph which was built by a current LJMU PhD student, Andrzej S. Piascik. All the data used are publicly available from the LT data archive.

Insight Astronomy Photographer of the Year 2016, attracted over 4500 entries from 80 countries and all seven continents. This year saw the annual competition's first entry from Antarctica! The prizewinners were announced during a ceremony at the Royal Observatory Greenwich with the Liverpool Telescope image, “Iridis”, taking first place in the “Robotic Scope” category. The winning images offer a fascinating cross section of everything that can be considered astrophotography, encompassing pictorial landscape, views through powerful telescopes, highly technical image processing and even social commentary.

Creator of the "Iridis" image, Robert Smith, says he was inspired to create it when considering the idea of ‘science as art’. We often hear about the idea of representing scientific data in an appealing way as an expression of art, but why not look at it the other way around; ‘art as acience’? Astrophotography is not just a matter of making science look pretty, it shows us that beauty actually is science. The winners of this competition were obviously selected because they were beautiful, striking or interesting, but each and every one is also an expression of astrophysical processes and could be the basis of a science seminar in their own right. It is physics that creates that beauty. Looking at the swirling gas in a nebula or the aurorae, you are literally seeing maths and physics.

All the winning entries may be seen in a free exhibition at the Royal Observatory in Greenwich which runs until June next year and in the Insight Astronomy Photographer of the Year 2016 show, available to planetaria worldwide. Quite apart from seeing the Liverpool Telescope's contribution, a visit to the exhibition is very much worth while if you are near Greenwich over the next year. All the winners and short listed entries are absolutely spectacular and inspiring both in their artistry and science.

IAPY exhibition at ROG
"Iridis" among the exhibition of winning entries on display at the Royal Observatory Greenwich.
The Liverpool Telescope's tracking of Gaia 23 September 2016
Gaia spaceraft
The Gaia spacecraft (credit: ESA)

The extremely high precision of the recent Gaia Data Release 1 (DR1) catalogue of star positions and velocities is due in part to very accurate tracking of the Gaia satellite itself from the ground.

Delta-DOR radar tracking by the European Space Agency's Deep Space Antenna network achieves this accuracy, but the network has many missions to cater for and cannot track Gaia every day. Therefore the Liverpool Telescope (LT) and the European Southern Observatory's VLT Survey Telescope (VST) also track Gaia, with the Las Cumbres Observatory's twin Faulkes Telescopes providing backup in case of problems with the LT and VST at the same time..

A recent article in the news website The Conversation goes into this in more detail. Read the full story here:

How we’re helping the Gaia mission map a billion stars to unparalleled precision

LT adds spectroscopy to its automatic rapid-response capabilities 5 August 2016

Simplified flowchart of user RTML submission to LT.
© 2016 LT Group

The low-resolution spectrograph SPRAT recently joined IO:O and IO:I as an instrument that can also be accessed by an alternative method — that in some cases can be faster, more convenient, and allow for immediate response to transient events (TAC permitting of course). This method is RTML.

RTML and the LT

Regular users of the Liverpool Telescope (LT) will be familiar with the standard method of setting up their observations, namely the Java-based Phase 2 User Interface or "Phase2UI".

This user interface, accessible only to registered users of the LT, enables them to manually define their observation details: the coordinates of their targets; the timing of their observations; the instruments and filters to be used; and the number and length of the exposures. The interface transmits this information directly to the telescope's Phase 2 database, which is polled by the robotic scheduler repeatedly through the night between observations to decide what to observe next — i.e. to match the best observation to current conditions.

If using the Phase2UI at night, the new or updated observation group will be considered by the scheduler as soon as it makes its next poll. So it could potentially be chosen and observed mere seconds after the "Submit" button is pressed.

What may not be so widely known is the alternative way of entering observation details, which in some cases is faster and more convenient. It uses the "Remote Telescope Markup Language" (RTML) protocol*, which was invented in 1989 at the University of California at Berkely, USA. It's a special dialect of XML (Extensible Markup Language), and is used to remote-control telescopes, or to communicate with autonomous robotic telescopes.

We provide two different ways to use RTML to send your observation details to the LT. Like the Phase2UI, both of them insert the information straight into the phase 2 database. The advantage however is that they allow you to automate the Phase 2 process, particularly useful if you have a lot of targets or observation groups to enter. The two RTML interfaces are:

  • command-line tools:
    • one tool to generate the RTML, and another to send the RTML directly to the LT
    • can be incorporated into customised scripts and programs
    • example use: generating and entering many targets quickly
  • LT-specific RTML Application Programming Interface (API):
    • allows users to build their own customised GUI tools at their institutions
    • GUI makes use of API to generate RTML and send directly to LT

We have in the past provided a third interface: bespoke webpages created by us for users who do not want to program with the command-line tools or API. These restricted-access pages contained HTML forms tailored to a user's specific observing programme. They generated observation details in RTML and transmitted directly to the LT. These pages are now being phased out.

Rapid-response overrides

Both RTML interfaces can also talk directly to the Target of Opportunity Control Agent (TOCA), the system that triggers the LT's rapid-response capability to interrupt the current observation and immediately observe your target instead. The LT already does this for Gamma-Ray Burst alerts via a different protocol, but it's also possible via RTML.

As you can imagine, overrides can be very disruptive. Therefore permission to have TOCA capability has to be requested at the Phase 1 stage and approved by the TAC.

RTML-capable instruments

RTML capability is being phased in across the LT's suite of instruments. IO:O and IO:I have been available for RTML response for some time, and now SPRAT has been added to the list. FRODOSpec and RISE are next, and we hope to have them available soon.

Applying for RTML capability

The RTML facility is available to all users who have TAC-awarded time allocations. Please contact us if this sounds interesting, and we will provide full user instructions.

* Not to be confused with the entirely different proprietary programming language used exclusively by Yahoo!'s web hosting services – their RTML stands for "Robert T. Morris Language".

Liverpool Telescope Involved in Gravitational Wave Followup Campaign 20 June 2016

Artist's impression of the two binary black hole systems discovered by aLIGO. Credit: LIGO/A.Simmonet

The Liverpool Telescope (LT) is part of a followup collaboration of telescopes set up to find the electromagnetic (EM) component of gravitational wave events detected by the Advanced Laser Interferometer for Gravitational-wave Observations (aLIGO). The flare of light is not expected to last long, so the "traditional" telescopes that detect only EM radiation must respond rapidly to characterise the source objects.

The LT helped in the search for the EM component for the very first gravitational wave (GW) detection event on 14th September 2015. It did so again for the second event, which although announced by aLIGO last week (see https://www.ligo.caltech.edu/news/ligo20160615), actually occurred on 26th December 2015.

aLIGO alerts of GW events are passed to observatories for followup as little as 30 minutes after detection. They give a search area within which the GW event could have occurred. This search area however is huge, and only facilities with very wide fields of view can efficiently make the initial sweep to look for new transient objects. Once flagged, the LT and other EM facilities can characterise each candidate in the list.

In both events no EM facility found an EM component, but the strategy for instant followup of such alerts is now in place, and has been tested successfully several times.

In a paper entitled "Liverpool Telescope follow-up of candidate electromagnetic counterparts during the first run of Advanced LIGO" Chris Copperwheat et al discusses the LT contribution to the follow-up campaign, and describes in detail the LT's followup strategy and its observations of the candidates GW objects. The paper is currently available from here: https://arxiv.org/abs/1606.04574.

Memorandum Of Understanding signed for development of new 4-metre class telescope 7 April 2016

Artist's impression of the new telescope.
Credit: J. Marchant, LT Group

Adapted from a story that appeared on the LJMU News site on 4 April 2016. That story also received coverage on BBC Online.

LJMU Vice-Chancellor, Prof Nigel Weatherill and the Director of the Instituto de Astrofisica de Canarias (IAC) Prof Rafael Rebolo López have signed a Memorandum of Understanding to explore the design, construction and operation of the new 4.0 metre telescope which will be on a bigger scale than the current Liverpool Telescope (LT) which has been studying the cosmos and making discoveries for over a decade.

The new telescope will be built on the Spanish Canary Island of La Palma and will be 4 times more sensitive and 10 times faster to respond to unexpected celestial events than the current world-record-holding 2-metre LT, also based on La Palma.

The new optical telescope will have the capability to see deeper into the cosmos, observe exploding stars (supernovae, gamma ray bursts, exoplanets and binary stars) and search for new planets, enabling a different type of science. This kind of study (time-domain astrophysics) will greatly increase in the coming decades, therefore the development of the new 4-metre class facility is vital in being able to explore the Universe in greater detail than ever before.

As well as being scientifically world-leading, the design and construction of the new telescope will exploit new technologies in advanced materials, optics and control systems. Researchers are keen for businesses in the region to provide that technology.

The project is also very exciting for the National Schools’ Observatory, which currently gives school children free access to the LT, and will expand to make use of the new telescope, creating an unrivalled opportunity to enthuse a generation of children about science, technology, engineering and mathematics.

Professor Iain Steele from LJMU's Astrophysics Research Institute (ARI) said: "The timing of this agreement is perfect. With new international discovery facilities like the LIGO and Virgo gravitational wave detectors and the Large Synoptic Survey Telescope coming on line over the next decade, a new high sensitivity spectroscopic capability is desperately needed. The new telescope will fill that niche perfectly”.

Professor Chris Collins, Head of the ARI, added: “This is a major opportunity to greatly expand the excellent science currently carried out by the Liverpool Telescope to cosmological distances. Investigating the exotic physics which govern many distant ultra-energetic sources using data from a large and fast reacting new 4m robotic telescope will keep us busy for many years to come.”

Dr Johan Knapen, IAC, commented: "The project builds on the hugely successful collaboration between LJMU and the IAC in building and operating the LT, which has been making discoveries for a decade. We look forward to working closely with LJMU in this project, which is of the highest calibre both technologically and scientifically."

Professor Rafael Rebolo López, IAC, said: "The new telescope will identify hundreds of exceptional astronomical sources each year, from binary black holes and supernovas, to counterparts of gravitational waves sources. By linking the new telescopes observations with those we can make with the Gran Telescopio Canarias we will be able to characterize these new sources in great detail. Both telescopes complement each other very well.”

Prof Ahmed Al-Shamma'a, Dean of the LJMU Faculty of Engineering and Technology said: "The combination of expertise of LJMU's Faculty of Engineering and Technology and the IAC's leading role as a technology development centre for astronomy puts in a unique position to deliver the technology needed for the project. The new telescope is now in the initial design phase and will be of interest to research centres, universities and companies that want to stand out in a technology sector that will have a major development in the coming decades.”