Surveys

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Surveys - essentially mapping the sky - play a pivotal role in all observational  astronomy for example by providing the catalogues of objects and their properties. Surveys in different part of the electromagnetic spectrum give us a multi-wavelength view of the Universe and a means to make an accurate census of different object types.

We are currently engaged in several major survey projects:

  • we lead the XMM-Newton Serendipitous Sky Survey activities through our PI role in the XMM-Newton Survey Centre (SSC). Main projects underway are the compilation of the XMM-Newton Serendipitous Source Catalogues and the SSC 'XID' Program:
      XMM-Newton Serendipitous Source Catalogues. Pointed observations with the XMM-Newton Observatory detect significant numbers of previously unknown 'serendipitous' X-ray sources in addition to the original target. Combining the data from many observations thus yields a serendipitous source catalogue which, by virtue of the large field of view of XMM-Newton and its high sensitivity, represents a significant resource. The serendipitous source catalogue enhances our knowledge of the X-ray sky and has the potential for advancing our understanding of the nature of various Galactic and extragalactic source populations. The first XMM-Newton catalogue (1XMM, released in 2003) contains 33000 X-ray source detections from 585 XMM-Newton observations. A prelease version of the second XMM-Newton Serendipitous Source Catalogue (2XMMp, released in July 2006) contains 153105 X-ray source detections relating to 123170 unique X-ray sources, drawn from over 4 times as many observations. The full 2XMM catalogue is currently under construction.
    • The SSC XID Program. This is a major program of identification and follow-up of sources detected in the XMM-Newton serendipitous sky survey. The program, which started in 2000, involves ground-based optical imaging and spectroscopy of well-defined samples from selected XMM-Newton fields. Imaging is required both to locate potential candidates accurately and reveal their morphology, whilst the optical spectroscopy provides the diagnostics needed both for object classification and for determining basic object parameters such as redshift and spectral slope. The principal objective is to obtain a completely identified sample which can be used to characterise the XMM-Newton source population overall sufficiently well that we can use the basic X-ray and optical parameters to assign a ‘statistical’ identification for a large fraction of all the sources in the XMM-Newton serendipitous source catalogue.  Large parts of the XID program, which involves the whole SSC Consortium led by Leicester, are nearing completion and to date well over 2000 X-ray sources have been identified from a selected sample of over 4000 objects.
  • we play a leading role in the XMM-Newton Slew Survey (XSS), processing all the data taken as XMM-Newton slews between targets. This survey, covering to date over half the sky, has catalogued tens of thousands of X-ray sources, many previously undiscovered. In the medium-energy X-ray band, the XSS reaches an order of magnitude deeper than any other all-sky survey, and in the low-energy band, the XSS reaches the same depth as the best previous survey, allowing a huge-area study of X-ray variability and rare transients. Highlight discoveries include the closest example of the tidal disruption of a star by a supermassive black hole at the centre of a normal galaxy, and perhaps the brightest nova for a decade - and the first ever to be discovered in X-rays rather than in the optical. It is only when an extremely large fraction of the sky is observed, as here, that such rare events have a chance of being discovered.
  • we lead a major part of the UKIDSS project which is using the WFCAM on the UK Infrared Telescope (UKIRT) in Hawaii to conduct the next generation near-infrared sky survey. Leicester leads the UKIDSS Large Area Survey (LAS) which aims to cover 4000 sq.deg. in 4 near-IR colours. The principal science goals of the LAS are: 1) surveys for the coolest T+ dwarfs and the nearest lowest-mass dwarfs; 2) surveys for z>6 and KX quasars; 3) multiwavelength photometry of SDSS galaxies; 4) detection of cool stars with high proper motions (cool white dwarfs and Pop II brown dwarfs).
  • we play a leading role in  the SuperWASP project, the UK's leading extra-solar planet detection program which involves a consortium of six academic institutions in the UK, together with the Instituto de Astrofisica de Canarias and  the Isaac Newton Group of telescopes. SuperWASP consists of two robotic observatories. The first, SuperWASP-North is located on the island of La Palma amongst the Isaac Newton Group of telescopes (ING). The second, SuperWASP-South is located at the site of the South African Astronomical Observatory (SAAO), just outside Sutherland, South Africa. The observatories are identical and consist of 8 wide-angle cameras that simultaneously monitor the sky for planetary transit events. A wide range of other scientific goals are also being pursued using SuperWASP data, for example the study of transient and moving optical objects such as gamma-ray bursts and potentially-dangerous Near-Earth Objects (NEOs). The WASP data set will build into an invaluable resource for all-sky time-domain astrophysics. Leicesters hosts the SuperWASP archive, developed here.

 

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