{\bf Photometric Performance of the Wyoming Infrared Observatory Prime-focus, Near-infrared Camera}

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Session 10 -- Remote Observing, Ground-Based Telescopes and Instruments
Display presentation, Monday, 9, 1995, 9:20am - 6:30pm

[10.11] {\bf Photometric Performance of the Wyoming Infrared Observatory Prime-focus, Near-infrared Camera}

D. Barnaby, P.E. Johnson, E.J. Spillar (WIRO)

The Wyoming Infrared Observatory (WIRO) prime-focus, near-infrared camera (nicknamed ``Babe'' after the famous ox of the same color) was designed specifically for wide-field imaging between 1 to 2.5 $\mu$m. To achieve the wide field-of-view, we mount the camera at the prime focus of the WIRO 2.3-meter telescope, a configuration which provides the camera with a total square field-of-view of 2$\stackrel{^{'}}{_{.}}$08 x 2$\stackrel{^{'}}{_{.}}$08. Since achieving first light in the summer of 1989, several scientific papers have been published based upon galaxy images obtained with this camera (for instance, Barnaby \& Thronson 1994). The design and construction of the camera have been covered by Spillar et\hspace{0.1em} al. \hspace{0.1em} (1990), however the photometric accuracy and repeatability of this camera have not been described before now.

In this paper, we show photometry obtained with the camera of calibration stars with near-infrared magnitudes ranging from 7$^{\rm m}$\hspace{0.5em} to 14$^{\rm m}$. These measurements indicate that over this range in brightness, the zero-point magnitude shifts about +0.06$^{\rm m}$\hspace{0.5em} while the relative uncertainty increases from 0.03$^{\rm m}$\hspace{0.5em} to 0.1$^{\rm m}$. In addition to photometry of calibration stars, we report on data comparing Babe near-infrared photometry of the galaxy M51 to photometry obtained by authors using other near-infrared aperture photometers and cameras. This comparison shows our photometry is consistent to within 0.1$^{\rm m}$\hspace{0.5em} with these other measurements down to a surface brightness of 18$^{\rm m}$\hspace{0.1em} arcsec$^{-2}$. These data, then, indicate that we can use our camera to measure near-infrared surface brightness of galaxies with a relative uncertainty of about 0.1$^{\rm m}$\hspace{0.5em} and a systematic uncertainty of about 0.1$^{\rm m}$.

This work was supported by NSF through grant AST-9117096 and EPSCoR grant RII-8610680 and by a Theodore Dunham, Jr. Grant from the Fund for Astrophysical Research. \\

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