In January 2001 an IR camera on long-term loan from the US Naval Obseravatory was commissioned on the Perkins 72-inch. The instrument consists of a NICOMOS 3 (HgCDTe) detector, good out to 2.5 microns. The gain is 15 e/ADU, with 45 e read noise, and 10 e/sec/pixel dark current. The full-well is estimated to be 17000-18000 ADU (250,000-270,000 electrons). It is a 256x256 40-micron device, and at the 72inch the scale will be approximately 0.26"/pixel,with a field of view of 66"x66". The filter complement includes J,H,K,K', and Klong. JHK are very close to standard JHK, i.e. small color terms in photometric transformations. K' cuts off the long end of the K band to reduce the thermal background. Klong is a poor-man's methane filter, useful for suppressing the disks of the outer planets.
Furthermore, if the filter wheel is run when it is warm, the motor and/or the gearing could be destroyed. Thermal contraction from cooling the wheel is required before it will run.
Email will be sent to "72failure" in the event the the dewar begins to warm up. Instructions for how to deal with such an event are detailed here.