1. Overview of NIRIM

NIRIM is a near-infrared imager based on the NICMOS3 256x256 detectors developed for HST. The camera was designed and built by Margaret Meixner at the University of Illinois and has been used extensively at the 36-inch telescope at Mt. Laguna outside San Diego, and at Mt. Wilson. Details about the camera can be found in Meixner, Young Owl, and Leach (1999, PASP, 111, 997). NIRIM is being made available to the WIYN Consortium scientists for roughly 4 months per year through an agreement with the University of Illinois. Questions, comments, or suggestions regarding this manual should be directed to Patricia Knezek, knezek@noao.edu.

With its triple optical system, NIRIM has the following characteristics at WIYN depending on which optical train has been selected (changing the optical train is not a user selectable function, but can be performed by the telescope operator).

field of view	0.7', 1.5', or 2.9'
pixel scale	0.17", 0.34", or 0.69"
read time	0.2 seconds
limiting mag (JHK') in 1 min	21.3, 20.6, 19.5
backgrounds (JHK') (summer)	15.4, 13.5, 11.6 mag/arcsec²

NIRIM has a complement of 14 filters in a pair of 8-position filter wheels (one position in each filter wheel is open). These include broad-band filters I, J, H, K', and narrow-band filters CI (0.985 mm), HeI (1.083 mm), FeII (1.644 mm), Brg (2.166 mm), H₂ (2.122), and the CO band head (2.295 mm). There are also three continuum filters at 1.064 mm (1% filter), 1.55 mm (2% filter), and 2.275 mm (2% filter). The last filter slot contains a cold plate. These are computer selectable by the observer.

An unusual feature of NIRIM is that the detector can be moved forward or backward within the dewar to accommodate the focus demands when the plate scale is changed and possibly for large changes across the wavelength range. Moving the detector can be dangerous and should be left to the WIYN personnel.