NICMASS at the MDM Observatories

Through special arrangement with the Michigan-Dartmouth-MIT consortium, a near-infrared direct imager was built for use with the 1.3m McGraw-Hill and 2.4m Hiltner telescopes at the MDM Observatories, Kitt Peak, Arizona. The focal plane instrument incorporated was the NICMASS infrared camera discussed in Appendix A. A flat mirror re-directs the beam from the Cassegrain focus through the re-imaging optics and onto the detector. Re-imaging optics consist of a warm ZnSe anti-reflection coated doublet that images the secondary onto an oversized cold stop inside the dewar. At F/13.5 on the 1.3m, the re-imaging optics give a platescale of 0.81 arcsec pixel resulting in a field of view of 3.4 arcmin on a side. The minimum exposure time of 0.6 seconds results in automatic saturation of all stars brighter than K = 7.0 on the 1.3m under good seeing conditions. Exposures are limited to less than 150 seconds due to saturation of the H-band background flux, and less than 30 seconds at K-band. The J-band exposures of 10 minutes are not prohibited by background flux. Filters include standard broadband J- (1.25 µm) and H-band (1.65 µm) filters, the K-band (2.2 µm) filter, as well as the narrow-band filters listed in Appendix A. The 80486 data acquisition computer has an interface to the telescope control system to enable mosaic mapping observations. This computer can also be connected to Sun workstations via ethernet to transfer data for reduction.