This is a very important magnitude to determine the threshold of detectability in near-infrared wavelengths. Sky brightness can be determine as follows,
SKYB = ZP - 2.5log(SK/scale2)
where ZP is the Zero Point, SK are the counts/sec/pixel from the sky
and scale is the angular scale at the detector. The sky brightness is measured
in magnitudes per arcsec2.
These values were obtained on 25 August 2001.