CFHT UM2019 - Presentation Details

Abstract Details

Title: MegaPipe 2.0: 10000 square degrees of CFHT MegaCam imaging

Presenter: Stephen Gwyn


MegaPipe, the MegaCam data processing pipeline at the CADC, hasbeen upgraded to version 2.0 and has processed over 10000 squaredegrees of the sky. MegaPipe has been operating since 2008 andhas resulted in close to 200 publications. It was originallyintended to increase the usage of archival MegaCam data bycalibrating and stacking the images as they became public. Thatfocus expanded to include processing data from the CFHT LargePrograms such as the NGVS, OSSOS, VESTIGE and CFIS, as well as PIdata. MegaPipe 2.0 represents several improvements. The advent ofGAIA means that the astrometric calibration is considerably moreaccurate. The public release of Pan-STARRS allows photometriccalibration of images even if they were taken undernon-photometric conditions, by using the PS1 stars as in-fieldstandards. Together this means that almost every MegaCam imagecan be astrometrically/photometrically calibrated to sufficientaccuracy to allow stacking (30 mas and 0.01 magnitudesrespectively). MegaPipe 2.0 also introduces an improvement to thestacking method. MegaPipe previously only stacked images thatwere centred on more or less the same part of the sky, whichlimited the number of images that could be stacked. MegaPipe 2.0instead stacks on a grid of 10000x10000 pixel tiles, each half adegree square, evenly covering the whole sky. The result is thattwice as much sky area can be stacked. There are now over 10000square degrees of imaging in both the ugriz filters as well asthe narrow band filters.