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Hubble Space Telescope
Sky Rough Estimate

This option merely selects between "average" sky background conditions, and "high" and "low conditions.

Values assumed are:

Low = 23.3 V mag arcsec-2 which represents minimum zodiacal light for sources at high ecliptic latitudes.

Average = 22.5 V mag arcsec-2 which represents average zodiacal light.

High = 21.0 V mag arcsec-2 which represents maximum zodiacal light + reflected earth light.

John Biretta <biretta@stsci.edu>, STScI