The SuperWASP Surveys
• Two reasonably identical facilities –La Palma (SuperWASP) and SAAO (WASP‐S). SuperWASP first season 2004, closed 2005, WASP‐S + SuperWASP from 2006 on.
• Each has 16 million CCD pixels and takes images at a rate of about 2 per 1‐1.5 minutes => 80‐100GB/night
• La Palma => electronic transfer
SAAO => Tapes
The SuperWASP Cameras
SW-S SAAO
SW-N La Palma
Performance
• Optimized to maximize number of bright stars => big fov, relatively large plate scale ~14arcsec per pixel.
• Sky Very bright at this scale => detection limit is about V=16.5 • Objects in range 8‐13 => photometry <1% often <0.5%
• Can map the entire visible sky every 23 minutes SuperWASP Field of View
4 camera mosaic of
Orion
SuperWASP RT Pipeline
• Based on the Cambridge pipeline tools, currently lashed together not optimized
• Data is reduced (bias, ff, astrometry, photometry) within 2 minutes
• Transient detection software + 1m telescope interface still to be written
WASP data reduction pipeline
Flatfield
Bias
Pre-processed
Raw
Dark
Current
Exposure
Map
16h43+31d26 field 2004 May-Aug
1
Flux-RMS
Leicester
Archive
0.1
Series1
0.01
0.001
9
10
11
12
WASP V magnitude
13
14
Field
recognition,
astrometry,
aperture
photometry,
calibration/detrending
Normal Data Reduction
• Data reduction responsibility of managing sites (ie QUB for SuperWASP, Keele for WASP‐S)
• At QUB, data reduction commences within a few hours of the complete data set for the night arriving at QUB
• Usual reduction steps + sophisticated image identification/analysis/detrending codes • Takes longer to reduce than it takes to obtain
• Catalogues transferred to analysis archive at leicester Pipeline Upgrades
• MkII pipeline (Andrew Cameron, St Andrews) will also include image subtraction
• Better feedback to hardware to control sources of systematic noise
Redundancy
• 10TB on La Palma
• On arrival at QUB or immediately tape is unpacked at Keele, copy of data sent to Atlas – petabyte tape storage at Rutherford
• Further tape copy at QUB and store about 6‐
12months worth on‐line incase visual inspection needed (eg Comet Holmes) or reanalysis require. • Reduction redundancy (machines)
Data rate + Sky Coverage Star counts
No of points per star
Planet fields at: +28,+05 (SW-N) and -28, -05 (SW-S)
Reached 1.5x1011 points (2008) in the Leicester archive
WASP Database
• Heart of the WASP project – measurements from both facilities (reduced and raw data products stored on line)
• Located at Leicester, designed and run by Richard West
• All analysis software (eg transit hunting) goes on directly on the database. Results from searches also stored in db.
• ESP explorer software (keele) used to search results and compare with catalogues etc – this has been vital to the success of WASP Lessons from WASP
• Only as good as your algorithms – it took some time “rediscovering” other groups planets in the WASP datasets in order to improve our detection rates. My worry is that now that is exactly what we find – objects similar to those already discovered. Try and keep things as general as possible
• Instant data reduction vital for QC purposes and also vital to the detection of very short duration transient events (eg accreting supermassive BH’s)
• Data transfer maybe not vital, but extremely useful
Lessons from WASP
• Systematic noise sources
• Spectral dependence of structures on chip surfaces => implications for flat fielding
• Analysis goes on in the db – need good coms, move as little data at this point as possible.
• User friendly search tools vital