The WASP (Wide Angle Search for Planets) project is an ultra-wide angle automated photometric survey, with the primary science goal of discovering transits of 'hot Jupiters'. SuperWASP-I, based on La Palma, Canary Islands, will begin fully robotic operations in 2005 with 8 cameras on a single fork mount, after running throughout April-November 2004 with 5 cameras. Construction of SuperWASP-II will begin at its South African site in mid-2005. The expected planet yield is of the order of a few tens per year, from a data flow of ~10-20 Tb of data per year. To deal with this vast amount of data, we have developed a custom-built data reduction pipeline and archive facility. Good transit candidates are expected from mid- 2005. 1. Abstract Precise transit photometry can reveal the signature of planets moving across the disk of their star (as illustrated, right). WASP follows the broad-shallow strategy in which thousands of bright stars are observed for the ~1% transits which announce Jupiter-radius companions. This ensures that candidate transiting objects will be well-suited for spectroscopic follow-up to eliminate the false-positives. Transiting exoplanets are revolutionising our understanding of exoplanet physics, as currently they offer the only method of probing the inner structure, by providing a density from a true mass determination and planetary radius constraints (e.g. Sozzetti et al 2004). SuperWASP-I is by far the widest-field photometric survey currently in operation that is capable of better than 1% precision required for Hot-Jupiter transits, with a total field of view over the eight cameras nearly 500 square degrees. 2. Transit Photometry star plane t intensi ty time 3. SuperWASP Specifications and Potential Yield Each of SuperWASP's-I 11cm aperture cameras has a 7.8°x7.8° field of view, to observe thousands of stars at magnitudes 7<V<15, with better than 1% photometric precision for magnitudes up to ~12. Each monitored field contains ~10,000 stars with V<12. Of these, around 14-19% are late-type F-M stars of which ~2% are expected to harbour giant planets, based on results from a decade of radial velocity surveys. Of those with planets, around 5% should present a transiting orientation. This results in ~1.5 real transits per field, being monitored for around 40 days. The plot to the right gives rms versus flux, showing the achieved photometric precision for a range of magnitudes. Current Status of the WASP Project B. Enoch 1 , W.I. Clarkson 1 , D.J. Christian 2 , A. Collier Cameron 3 , A. Evans 4 , A.Fitzsimmons 2 , C.A. Haswell 1 , C. Hellier 4 , S.T. Hodgkin 5 , K. Horne 3 , J. Irwin 5 , S.R. Kane 3 , F.P. Keenan 2 , T.A. Lister 3 , A.J. Norton 1 , J.Osborne 6 , D.L. Pollaco 2 , R. Ryans 2 , I. Skillen 7 , R.A. Street 2 , R.G. West 6 , P.J. Wheatley 6 6 1 2 4. Data reduction pipeline ● Pre-existing photometry software is inadequate for the wide FOV of the WASP cameras. A custom-built data pipeline has been developed: ● Statistical frame-classification using minimal input assumptions ● Optimal combination of master calibration frames from several nights, weighted by time interval and by quality ● Calibration using flat, dark and bias frames, and correction for shutter travel time ● Full astrometric solution of FOV using Tycho2 catalogue (<15 mag) ● Object identification using USNO- B1 catalogue. Photometry performed for 3 separate apertures allowing a measure of object blending ● Non-matched objects may be transient outbursts, gamma-ray bursts or asteroids; flagged as orphans for later re-examination Flat Dark Bias Exposure map ● Post-photometry calibration; convert SW-I count rates to visual magnitudes from iterative fit to 9-term photometric model ● End-product can be queried flexibly from WASP archive based at Leicester University, which forms the primary interface to all post-processed science data. Time-evolution of object properties stored by keyword, (e.g. flux, CCD position vs time). Further keywords can be added as desired. Archive-query tools developed using custom-written WASP query language. 5. Preliminary Results These figures show example lightcurves from the 2004 SW-I dataset, revealing large- amplitude (left) and low-amplitude (at the 1% level, right) variability of a selection of sources of interest. This demonstrates that SW-I has achieved the necessary <1% accuracy that will be needed to detect transiting exoplanets. A rich, comprehensive database ● Fully robotic, unattended operation of SW-I will begin with 8 cameras in 2005. ● Further refinement and optimisation of the pipeline throughout early 2005. ● Construction of the clone facility SW-II at the South African Astronomical Observatory, mid-2005. Christian D.J. et al., 2004 astro- ph/0411019 Kane S.R. et al., 2004 MNRAS 353,689 Sozzetti A. et al, 2004 ApJ Lett 616, 167 6. The Future 7. References & Further Information 3 4 5 7 Left: Schematic of exoplanet transit (top), and a real transit-lightcurve of HD209458B, taken with the WASP0 demonstration prototype (Kane et al 2004) Above: Planetary mass-radius trend for transiting exoplanets. From Sozzetti et al (2004). Views of the SW-I Facility. Flow-diagram of the reduction pipeline stages. Example frames from the automated pre-processing. Flux-RMS diagram of all lightcurves from a single field of view for a single camera, from a sample of the 2004 SW-I dataset. Sample variable-star lightcurves from the 2004 SW-I dataset. Stellar lightcurves from the 2004 SW-I dataset showing 1%-level variations. Pre-processed image Raw image