VISTA pipelines summit pipeline: real time DQC verified raw product to Garching standard pipeline: instrumental signature removal, catalogue production, astrometric and photometric calibration further processing: generate well sampled PSF, PSF and Sersic profile fitting advanced pipeline: database driven, deep stacking and mosaicing, merging catalogues, list driven photometry, overlap calibration

Simple model: r` = k 1 r + k 3 r 3 WCS: ZPN PV2_1 PV2_3 Astrometry

Photometric Calibration effect of pixel scale change measure instrument ZP and extinction establish secondary standard fields full fov equatorial + zenith range of airmass coordinate with WFCAM 2MASS to choose range of colours and surface density, open clusters, faint standards monitor systematics in photometry narrow bands spectrophotometric stds

Observing modes Observing modes and FITS headers

Example using UDS survey from UKIDSS Interleave sequence

Data Transfers raw data i*4 in FITS format reset-corrected single reads/coadds are integer convert to Multi-Extension FITS (MEFs) ?? lossless Rice tile compression ?? data exported to Garching disks ?? tapes ?? Update headers using summit logs ?? transfer raw data to CASU how ?? online RAID-based MEFs raw data archive

Data Quality Monitoring I night time observing conditions instrument status values header and data verification summary of autoguider information and observer comments added to headers later

Data Quality Monitoring II sky brightness: saturated ? level ? no signal ? sky noise: rms ok ? pattern noise ? stellar ellipticity: trailed image ? average seeing: in focus ? stellar aperture correction: weird PSF ? no. spurious images: corrupted data ? astrometric errors: rms ok ? pointing ?

Data Quality Monitoring III photometric throughput cf. 2MASS locally photometric flag globally photometric flag limiting magnitude nightly photometric ZP from standards estimate of average extinction

WFAU tapes disks internet

Technical challenges ● non-linearity calibration and measurement ● cross-talk between channels and detectors ● image persistence from frame-to-frame ● sky level variations on short timescales ● rapid variability of OH fringing ● seeing variations on short timescales ● possible time varying flatfield characteristics ● calibration and extinction monitoring ● data volume and throughput ● robust automatic DQC measures