26 January 2007 CAL 07 Garching 1 The VISTA Data Flow System Jim Lewis, Mike Irwin, Peter Bunclark, Simon Hodgkin Cambridge Astronomy Survey Unit

26 January 2007CAL 07 Garching2 Introduction to CASU Small group within the Institute of Astronomy, specialising in survey astronomy. Small group within the Institute of Astronomy, specialising in survey astronomy. Pipeline reduction of imaging data Pipeline reduction of imaging data APM (Schmidt Plates 1 x 40k x 40k) APM (Schmidt Plates 1 x 40k x 40k) INT Wide Field Camera (4 x 2k x 4k) INT Wide Field Camera (4 x 2k x 4k) ESO WFI on 2.2m at La Silla (8 x 2k x 4k) ESO WFI on 2.2m at La Silla (8 x 2k x 4k) MOSAIC-1 on KPNO 4m (8 x 2k x 4k) MOSAIC-1 on KPNO 4m (8 x 2k x 4k) MOSAIC-2 on Blanco 4m at CTIO (8 x 2k x 4k) MOSAIC-2 on Blanco 4m at CTIO (8 x 2k x 4k) AAO WFI on AAT (8 x 2k x 4k) AAO WFI on AAT (8 x 2k x 4k) CIRSI on INT (4 x 1k x 1k) CIRSI on INT (4 x 1k x 1k) INGRID on WHT (1k x 1k) INGRID on WHT (1k x 1k) UFTI on UKIRT (1k x 1k) UFTI on UKIRT (1k x 1k) WFCAM on UKIRT (4 x 2k x 2k) WFCAM on UKIRT (4 x 2k x 2k)

26 January 2007CAL 07 Garching3 Introduction to VDFS PPARC funded facility to provide an end-to-end data-flow system for VISTA and WFCAM. PPARC funded facility to provide an end-to-end data-flow system for VISTA and WFCAM. Quality control and calibration pipelines Quality control and calibration pipelines Paranal and Garching Paranal and Garching Science pipeline for full calibration of science data. Science pipeline for full calibration of science data. Cambridge Cambridge Science archive acts as the point of access of the reduced data. Plus some further processing. Science archive acts as the point of access of the reduced data. Plus some further processing. WFAU, Edinburgh WFAU, Edinburgh

26 January 2007CAL 07 Garching4 Data Flow Raw telescope data is assessed by the summit pipeline (QC1) Raw telescope data is assessed by the summit pipeline (QC1) Shipped to Garching (discs) Shipped to Garching (discs) Shipped to CASU for science reduction and calibration. (discs) Shipped to CASU for science reduction and calibration. (discs) Calibrated data shipped to Edinburgh for archiving (ftp) Calibrated data shipped to Edinburgh for archiving (ftp)

26 January 2007CAL 07 Garching5 IR Data Reduction Worries IR detectors are currently inherently more unstable than optical CCDs. IR detectors are currently inherently more unstable than optical CCDs. Some odd electronic effects Some odd electronic effects Sky emission > 100x brighter than most objects Sky emission > 100x brighter than most objects And its variable both spatially and temporally! And its variable both spatially and temporally! Exposure times are short, so data rates are very high. Exposure times are short, so data rates are very high Gb/night expected for VISTA public surveys Gb/night expected for VISTA public surveys Rice tile compression can save factors of 3-4 in 32 bit integer data Rice tile compression can save factors of 3-4 in 32 bit integer data

26 January 2007CAL 07 Garching6 VDFS Pipeline Recipes Create master calibration frames (dark, twilight flats, confidence maps, etc) Create master calibration frames (dark, twilight flats, confidence maps, etc) Linearity analysis Linearity analysis Detector noise & dark current properties Detector noise & dark current properties Persistence and crosstalk analysis Persistence and crosstalk analysis Illumination correction analysis Illumination correction analysis Full reduction recipes for standard star and programme fields Full reduction recipes for standard star and programme fields

26 January 2007CAL 07 Garching7 Processing Steps Reset correction (debias) Reset correction (debias) Linearity correction Linearity correction Dark and reset anomaly correction Dark and reset anomaly correction

26 January 2007CAL 07 Garching8 Reset Anomaly (WFCAM)

26 January 2007CAL 07 Garching9 Processing Steps Reset correction Reset correction Linearity correction Linearity correction Dark and reset anomaly correction Dark and reset anomaly correction Flat field correction Flat field correction Background correction (defringing) Background correction (defringing) Destriping Destriping

26 January 2007CAL 07 Garching10 Stripes Close Up (VISTA)

26 January 2007CAL 07 Garching11 Stripes (VISTA)

26 January 2007CAL 07 Garching12 Processing Steps Reset correction Reset correction Linearity correction Linearity correction Dark and reset anomaly correction Dark and reset anomaly correction Flat field correction Flat field correction Background estimation and subtraction (defringing) Background estimation and subtraction (defringing) Destriping Destriping Image persistence and detector crosstalk removal Image persistence and detector crosstalk removal

26 January 2007CAL 07 Garching13 Crosstalk (WFCAM)

26 January 2007CAL 07 Garching14 Processing Steps Reset correction Reset correction Linearity correction Linearity correction Dark and reset anomaly correction Dark and reset anomaly correction Flat field correction Flat field correction Background estimation and subtraction (defringing) Background estimation and subtraction (defringing) Destriping Destriping Image persistence and detector crosstalk removal Image persistence and detector crosstalk removal Interleaving Interleaving Dithering/Jittering Dithering/Jittering Catalogue generation Catalogue generation Astrometric calibration Astrometric calibration Photometric zeropoint calibration Photometric zeropoint calibration (Tiling) (Tiling)

26 January 2007CAL 07 Garching15 Summit & Garching Pipelines QC1 parameters QC1 parameters e.g. photometric zeropoints, astrometric fit quality e.g. photometric zeropoints, astrometric fit quality Written using ESO qfits/CPL infrastructure Written using ESO qfits/CPL infrastructure Both use the same software modules Both use the same software modules Reduce a pawprint Reduce a pawprint Amount of processing can be scaled down Amount of processing can be scaled down Calibration images (flats etc) from a master library. Calibration images (flats etc) from a master library.

26 January 2007CAL 07 Garching16 Cambridge Pipeline Full reduction Full reduction Tiling and sky correction Tiling and sky correction Catalogue generation is done for both pawprints and tiles Catalogue generation is done for both pawprints and tiles Results shipped to WFAU Results shipped to WFAU Some of the same CPL based modules reused. Some additional modules required. Some of the same CPL based modules reused. Some additional modules required.

26 January 2007CAL 07 Garching17 Current Status of VISTA Pipelines Version 0.4 ESO pipelines currently being tested Version 0.4 ESO pipelines currently being tested Version 0.5 to be released end of February Version 0.5 to be released end of February Full compliment of recipes (almost!) Full compliment of recipes (almost!) PAE PAE WFCAM pipeline is a prototype for the extra functionality required by Cambridge VISTA pipeline WFCAM pipeline is a prototype for the extra functionality required by Cambridge VISTA pipeline

26 January 2007CAL 07 Garching18 A Typical Recipe Run…