Exposure times:	Must be integer seconds >= 1 sec.
Filters:	Y (data), J (data), H (data), K (data), zJ (data), HK (data), and a Dark position. (Data taken prior to August 2010 used the old HK filter.)
Focus:	Instrument focus is stable and is not changed. Telescope focus is provided by the wavefront sensor.
Sky background:	Dominated by narrow OH emission lines and broad H2O absorption bands (additional discussion).
Overhead:	14 sec total overhead per exposure, including 30 arcsec telescope dither.
Guiding:	Images are unguided.
Strategy:	Long integrations are made from a series of short exposures, otherwise the night sky quickly saturates the detector (see Imaging Senstivity table). Images are typically obtained in a dither sequence. Sky background is measured, and removed, by median-combining a set of dithered images. This works well for sparse fields and point sources, however observations of extended objects require dithering on an OFF field to measure the sky background. Worked example.

Slit mask field:	4 x 6.9 arcmin
Slitlets:	Recommend 0.4" wide slits at least 7" long (slit lengths can differ, but widths should be the same if possible)
Long Slits:	0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 2.4 x 420 arcsec
Wavelength coverage:	Provided by filters; grisms cannot be tilted.
Cal lamps:	Continuum, Argon
Telluric calibration:	Bright A0 stars
Observing Strategy:	Similar strategy as imaging, except that the target(s) must be dithered along the slit(lets). Exposure times can be much longer because the sky background is dispersed. In addition, argon lamp exposures are required at each pointing to perform wavelegth calibration, and a bright telluric standard should be observed at identical airmass.