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sin(alt)=sin(dec)sin(lat) + cos(dec) cos(HA) cos(lat)
Solid angle Omega subtended in an angle A from zenith is Omega=2pi*(1-cos(A)).
| A (Deg) | Omega(sr)/2pi | sq deg | N fields |
|---|---|---|---|
| 30 | 0.13 | 2681 | 280 |
| 45 | 0.29 | 5981 | 623 |
| 60 | 0.5 | 10313 | 1074 |
| 70 | 0.66 | 13607 | 1417 |
| 90 | 1 | 20626 | 2148 |
Sky Brightness from LSST ETC
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