The SAMI Galaxy Survey: cubism and covariance, putting round pegs into square holes

• Main Authors: Sharp, R, Lewis, GF, Leslie, SK, Lawrence, JS, Konstantopoulos, IS, Jones, H, Hopkins, AM, Hampton, EJ, Ho, IT, Gunawardhana, MLP, Goodwin, M, Foster, C, Driver, S, Drinkwater, MJ, Couch, WJ, Colless, M, Cecil, GN, Bryant, JJ, Brough, S, Bloom, JV, Bland-Hawthorn, J, Birchall, M, Bauer, AE, Barnes, LA, Taylor, EN, Scott, N, Richards, SN, Nielsen, J, Green, AW, Cortese, L, Croom, SM, Fogarty, LMR, Allen, JT, Walcher, CJ, Tonini, C, Thomas, AD, Sweet, SM, Schaefer, AL, Owers, MS, Obreschkow, D, Pracy, MB, Parker, QA, Mould, J, Mahajan, S, Medling, AM, McElroy, R, Lorente, NPF, López-Sánchez, ÁR, Liske, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University press. The Journal's web site is located at http://www.oxfordjournals.org/our_journals/mnras/ 2015
• Subjects: techniques: imaging spectroscopy; instrumentation: spectrographs; methods: data analysis; sami
• Online Access: http://hdl.handle.net/10722/211196

We present a methodology for the regularization and combination of sparse sampled and irregularly gridded observations from fibre-optic multiobject integral field spectroscopy. The approach minimizes interpolation and retains image resolution on combining subpixel dithered data. We discuss the methodology in the context of the Sydney-AAO multiobject integral field spectrograph (SAMI) Galaxy Survey underway at the Anglo-Australian Telescope. The SAMI instrument uses 13 fibre bundles to perform high-multiplex integral field spectroscopy across a 1° diameter field of view. The SAMI Galaxy Survey is targeting ˜3000 galaxies drawn from the full range of galaxy environments. We demonstrate the subcritical sampling of the seeing and incomplete fill factor for the integral field bundles results in only a 10 per cent degradation in the final image resolution recovered. We also implement a new methodology for tracking covariance between elements of the resulting data cubes which retains 90 per cent of the covariance information while incurring only a modest increase in the survey data volume.