UKIDSS website, technical section - filters.
The WFCAM Y filter (0.97-1.07µm) occupies the clean
range between the atmospheric absorption bands at 0.95µm and
1.14µm. The bandpass is similar to, but slightly narrower
than, the Y
bandpass of Hillenbrand et al. (2002, PASP, 114, 708). The
WFCAM Y filter (shown red) has a slightly redder cut-on wavelength
than the Hillenbrand Y filter (shown grey dash-dot), in order to be
clear of the atmospheric absorption band. The cut-off wavelength of
the WFCAM Y filter is at a significantly bluer wavelength, and largely
avoids the strong sky emission lines near 1.1µm. Not only
reduce the sky background, but it improves the Y-J colour
discrimination between high-redshift quasars and T dwarfs (as shown by
Warren and Hewett 2002).
WFCAM Y filter profile