  We describe test observations made with a customized 640 x 512 pixel Indium
Gallium Arsenide (InGaAs) prototype astronomical camera on the 100" DuPont
telescope. This is the first test of InGaAs as a cost-effective alternative to
HgCdTe for research-grade astronomical observations. The camera exhibits an
instrument background of 113 e-/sec/pixel (dark + thermal) at an operating
temperature of -40C for the sensor, maintained by a simple thermo-electric
cooler. The optical train and mechanical structure float at ambient temperature
with no cold stop, in contrast to most IR instruments which must be cooled to
mitigate thermal backgrounds. Measurements of the night sky using a reimager
with plate scale of 0.4 arc seconds / pixel show that the sky flux in Y is
comparable to the dark current. At J the sky brightness exceeds dark current by
a factor of four, and hence dominates the noise budget. The sensor read noise
of ~43e- falls below sky+dark noise for exposures of t>7 seconds in Y and 3.5
seconds in J. We present test observations of several selected science targets,
including high-significance detections of a lensed Type Ia supernova, a type
IIb supernova, and a z=6.3 quasar. Deeper images are obtained for two local
galaxies monitored for IR transients, and a galaxy cluster at z=0.87. Finally,
we observe a partial transit of the hot JupiterHATS34b, demonstrating the
photometric stability required over several hours to detect a 1.2% transit
depth at high significance. A tiling of available larger-format sensors would
produce an IR survey instrument with significant cost savings relative to
HgCdTe-based cameras, if one is willing to forego the K band. Such a camera
would be sensitive for a week or more to isotropic emission from r-process
kilonova ejecta similar to that observed in GW170817, over the full 190 Mpc
horizon of Advanced LIGO's design sensitivity for neutron star mergers.
