An integrated modeling framework for the Large Synoptic Survey Telescope (LSST)

Angeli, George Z.; Claver, C. F.; Cho, M.; Dribusch, Christoph; Neill, Douglas R.; Peterson, J. R.; Sebag, Jacques; Thomas, Sandrine

doi:10.1117/12.2234078

Cited by 7 publications

(2 citation statements)

References 9 publications

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“…where m sky is the sky brightness (AB mag arcsec −2 ), θ eff is the seeing (in arcseconds), t vis is the exposure time (seconds), k is the atmospheric extinction coefficient, and X is air mass. Here the seeing corresponds to the "effective" seeing computed from the seeing FWHM following the procedure described in Angeli et al (2016). The seeing FWHM in each band is listed in the second row of Table 2, and the effective seeing is listed in the third row of Table 2.…”

Section: Expected Photometric S/nmentioning

confidence: 99%

LSST: From Science Drivers to Reference Design and Anticipated Data Products

Ivezić

Kahn

Tyson

et al. 2019

ApJ

2,461

1,494

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We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the solar system, exploring the transient optical sky, and mapping the Milky Way. LSST will be a large, wide-field ground-based system designed to obtain repeated images covering the sky visible from Cerro Pachón in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg 2 field of view, a 3.2-gigapixel camera, and six filters (ugrizy) covering the wavelength range 320-1050 nm. The project is in the construction phase and will begin regular survey operations by 2022. About 90% of the observing time will be devoted to a deep-wide-fast survey mode that will uniformly observe a 18,000 deg 2 region about 800 times (summed over all six bands) during the anticipated 10 yr of operations and will yield a co-added map to r∼27.5. These data will result in databases including about 32 trillion observations of 20 billion galaxies and a similar number of stars, and they will serve the majority of the primary science programs. The remaining 10% of the observing time will be allocated to special projects such as Very Deep and Very Fast time domain surveys, whose details are currently under discussion. We illustrate how the LSST science drivers led to these choices of system parameters, and we describe the expected data products and their characteristics.

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Section: Expected Photometric S/nmentioning

confidence: 99%

LSST: From Science Drivers to Reference Design and Anticipated Data Products

Ivezić

Kahn

Tyson

et al. 2019

ApJ

2,461

1,494

View full text Add to dashboard Cite

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“…We modify the truth-catalogue properties of all faint sample (𝑖 < 26) galaxies to more accurately reflect LSST-like samples by convolving the galaxy sizes and shapes with a 𝜃 eff ∼ 𝜃 zenith eff X0.6 ∼ 0.9 circular Gaussian PSF -the "effective" PSF FWHM value expected at the median airmass of X = 1.2 for LSST where 𝜃 zenith eff = 0.8 is the "effective" zenith seeing FWHM for the 𝑖 band taken from Table 2 of Ivezić et al (2019). The reason we use these "effective" values is to account for the deviation of the LSST fiducial atmospheric PSF (a von Kármán type PSF) from the Gaussian shape (Angeli et al 2016) assumed here.…”

Section: Modified Galaxy Propertiesmentioning

confidence: 99%

Galaxy blending effects in deep imaging cosmic shear probes of cosmology

Nourbakhsh,

Tyson,

Schmidt

et al. 2021

Preprint

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Upcoming deep imaging surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time will be confronted with challenges that come with increased depth. One of the leading systematic errors in deep surveys is the blending of objects due to higher surface density in the more crowded images; a considerable fraction of the galaxies which we hope to use for cosmology analyses will overlap each other on the observed sky. In order to investigate these challenges, we emulate blending in a mock catalogue consisting of galaxies at a depth equivalent to 1.3 years of the full 10-year Rubin Observatory that includes effects due to weak lensing, ground-based seeing, and the uncertainties due to extraction of catalogues from imaging data. The emulated catalogue indicates that approximately 12% of the observed galaxies are "unrecognized" blends that contain two or more objects but are detected as one. Using the positions and shears of half a billion distant galaxies, we compute shear-shear correlation functions after selecting tomographic samples in terms of both spectroscopic and photometric redshift bins. We examine the sensitivity of the cosmological parameter estimation to unrecognized blending employing both jackknife and analytical Gaussian covariance estimators. A ∼ 0.02 decrease in the derived structure growth parameter 𝑆 8 = 𝜎 8 (Ω m /0.3) 0.5 is seen due to unrecognized blending in both tomographies with a slight additional bias for the photo-𝑧-based tomography. This bias is about 2𝜎 statistical error in measuring 𝑆 8 .

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