Sky Variability in the y Band at the LSST Site
| Autor: | Christopher W. Stubbs, F. William High, B. Stalder, D. K. Gilmore, John L. Tonry |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Physics
Pixel 010308 nuclear & particles physics media_common.quotation_subject Flux FOS: Physical sciences Astronomy and Astrophysics Field of view Large Synoptic Survey Telescope Astrophysics 01 natural sciences Camera lens 13. Climate action Space and Planetary Science Sky Sky brightness 0103 physical sciences Spatial variability Astrophysics - Instrumentation and Methods for Astrophysics 010303 astronomy & astrophysics Instrumentation and Methods for Astrophysics (astro-ph.IM) media_common |
| Popis: | We have measured spatial and temporal variability in the y band sky brightness over the course of four nights above Cerro Tololo near Cerro Pachon, Chile, the planned site for the Large Synoptic Survey Telescope (LSST). Our wide-angle camera lens provided a 41 deg field of view and a 145 arcsec pixel scale. We minimized potential system throughput differences by deploying a deep depletion CCD and a filter that matches the proposed LSST y_3 band (970 nm-1030 nm). Images of the sky exhibited coherent wave structure, attributable to atmospheric gravity waves at 90 km altitude, creating 3%-4% rms spatial sky flux variability on scales of about 2 degrees and larger. Over the course of a full night the y_3 band additionally showed highly coherent temporal variability of up to a factor of 2 in flux. We estimate the mean absolute sky level to be approximately y_3 = 17.8 mag (Vega), or y_3 = 18.3 mag (AB). While our observations were made through a y_3 filter, the relative sky brightness variability should hold for all proposed y bands, whereas the absolute levels should more strongly depend on spectral response. The spatial variability presents a challenge to wide-field cameras that require illumination correction strategies that make use of stacked sky flats. The temporal variability may warrant an adaptive y band imaging strategy for LSST, to take advantage of times when the sky is darkest. 8 pages, 5 figures, accepted to PASP. Minor changes from referee report and editor's revisions. |
| Databáze: | OpenAIRE |
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