Technical

The Mounts

WASP mount

Make: Torus fork mount Weight: 400 Kg
Pointing error: 30 arcsec RMS full sky Tracking error: < 0.01 arcsec per second
Controls: Stepper motors driven by Torus motion control electronics Time Standard: GPS receiver gives better than 1s synchronisation with UTC

The Cameras

WASP cameras

Lens: Canon 200mm f/1.8 Aperture: 11.1 cm
CCD: 2048 x 2048 thinned e2v by Andor of Belfast Pixel size: 13.5 micrometers
Readout noise: 12-18 e- (in 1MHz pixel readout speed) Gain settings: 2, 1.4, 0.7 e-/ADU
Maximum pixel count: 80,000 e- Field of View: 7.8 x 7.8 degrees
Plate Scale 13.7 arcsec/pixel Operating Temperature: -50 degree C
Cooling Mechanism 3-stage Peltier

The Enclosures

WASP enclosure

Maker: GRPro engineering Construction: reinforced fibreglass
Size: 3.5m x 8.5m Design: Camera room; computer room; retractable roof

The WASP cameras are operating robotically from the UK, and can be commanded over the internet. The observers web-page monitors the weather, the instrument status, and the incoming data.

WASP-South remote-observing page

The WASP cameras cover 1% of the night sky in each shot. They usually tile a set of fields, returning to each every 8 minutes. Approximately 7000 CCD images are taken on each clear night, amounting to 40 GBs of data. These are pipeline processed into photometric datapoints on each star, which are accumulated into lightcurves in the WASP archive.

WASP reduction pipeline

Search algorithms look for transits in each lightcurve of each star, producing a “candidate page” for each possible transit. A human looks at these to select the best planet candidates.

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The candidates are sent for radial-velocity observations, using telescopes such as the 1.2-m Swiss/Euler telescope at La Silla Observatory, equipped with the CORALIE spectrograph. The size of the radial-velocity motion tells us the mass of the orbiting body and thus tells us whether it is a planet.

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We also obtain the best-quality light-curves that we can, in order to best parametrise the planets.

WASP-4b transit

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