The Effect of the Earth's Atmosphere on LSST Photometry

Rahlin, Alexandra S. ; /SLAC, /MIT

Stanford Linear Accelerator Center

关键词: Aerosols;    Light Sources;    71 Classical And Quantum Mechanics, General Physics;    Instrumentation,Other;    Energy Spectra;   

DOI  :  10.2172/891240
RP-ID  :  SLAC-TN-06-022
RP-ID  :  AC02-76SF00515
RP-ID  :  891240

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Large Synoptic Survey Telescope (LSST), a ground-based telescope currently under development, will allow a thorough study of dark energy by measuring, more completely and accurately than previously, the rate of expansion of the universe and the large-scale structure of the matter in it. The telescope utilizes a broadband photometric system of six wavelength bands to measure the redshifts of distant objects. The earth's atmosphere makes it difficult to acquire accurate data, since some of the light passing through the atmosphere is scattered or absorbed due to Rayleigh scattering, molecular absorption, and aerosol scattering. Changes in the atmospheric extinction distribution due to each of these three processes were simulated by altering the parameters of a sample atmospheric distribution. Spectral energy distributions of standard stars were used to simulate data acquired by the telescope. The effects of changes in the atmospheric parameters on the photon flux measurements through each wavelength band were observed in order to determine which atmospheric conditions must be monitored most closely to achieve the desired 1% uncertainty on flux values. It was found that changes in the Rayleigh scattering parameter produced the most significant variations in the data; therefore, the molecular volume density (pressure) must be measured with at most 8% uncertainty. The molecular absorption parameters produced less significant variations and could be measured with at most 62% uncertainty. The aerosol scattering parameters produced almost negligible variations in the data and could be measured with > 100% uncertainty. These atmospheric effects were found to be almost independent of the redshift of the light source. The results of this study will aid the design of the atmospheric monitoring systems for the LSST.