Survey Design
Sky Coverage
The LSST will be sited on Cerro Pachon in northern Chile. From that site, sky regions with Dec<33.5 deg. can be observed at an airmass of 2.2 or smaller, a limit that is used to define the LSST Survey. This airmass results in a 0.6 mag loss of sensitivity at 500 nm compared to an observation in zenith (due to both seeing degradation and atmospheric absorption), and corresponds to an observable area of 31,000 sq.deg.
Sky regions with -75<Dec<+15 can be observed at an airmass of 1.4 or smaller, providing especially good image quality for weak lensing and other science investigations that require it. The total accessible solid angle in this range exceeds 20,000 sq.deg., outside of the confusion-affected parts of the galactic plane. Figure 3 summarizes these constraints in equatorial and galactic coordinates.
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Figure 3: A summary of observing constraints for LSST survey from Cerro Pachon, in equatorial (top) and galactic coordinates (bottom). The two dashed blue lines outline the 24,000 sq.deg. region for which the minimum airmass reaches values <1.4. The galactic plane regions with the highest stellar density are enclosed by solid red lines and include 1,000 sq.deg. |
Source: American Astronomical Society 213th Meeting, Poster Exhibit, "LSST: from science drivers to reference design and anticipated data products", Z. Ivezic et al., 460.03