Background-limited Imaging in the Near Infrared with Warm InGaAs Sensors: Applications for Time-domain Astronomy

We describe test observations made with a customized 640 × 512 pixel indium gallium arsenide (InGaAs) prototype astronomical camera on the 2.5 m DuPont telescope. This is the first test of InGaAs as a cost-effective alternative to HgCdTe for research-grade astronomical observations. The camera exhib...

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Bibliographic Details
Published in:	The Astronomical journal 2019-02, Vol.157 (2), p.46
Main Authors:	Simcoe, Robert A., F rész, Gábor, Sullivan, Peter W., Hellickson, Tim, Malonis, Andrew, Kasliwal, Mansi, Shectman, Stephen A., Kollmeier, Juna A., Moore, Anna
Format:	Article
Language:	eng
Subjects:	AMBIENT TEMPERATURE ASTRONOMY ASTROPHYSICS, COSMOLOGY AND ASTRONOMY Cameras Celestial bodies COMPARATIVE EVALUATIONS Cost control DARK CURRENT Ejecta ELECTRONS EMISSION Extrasolar planets Floats Galactic clusters Galaxies GALAXY CLUSTERS Gallium Gallium arsenide GALLIUM ARSENIDES Gas giant planets Indium INDIUM ARSENIDES Indium gallium arsenides Infrared astronomy Infrared detectors Infrared imaging INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY instrumentation: detectors Jupiter Mercury cadmium tellurides MILKY WAY Night sky NOISE Outerwear Pixels QUASARS R PROCESS SENSORS STABILITY SUPERNOVAE TELESCOPES THERMOELECTRIC COOLERS Thermoelectric cooling Tiling Transit
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Summary:	We describe test observations made with a customized 640 × 512 pixel indium gallium arsenide (InGaAs) prototype astronomical camera on the 2.5 m DuPont telescope. This is the first test of InGaAs as a cost-effective alternative to HgCdTe for research-grade astronomical observations. The camera exhibits a background of 113 e- s-1/pixel (dark + thermal) at operating sensor temperature T = −40°C, maintained by a simple thermoelectric cooler. The optomechanical structure floats at ambient temperature with no cold stop, unlike most IR instruments which must be cooled to mitigate thermal backgrounds. Measurements of the night sky using a reimager scaled at 0 4/pixel show that the sky flux in Y is comparable to the dark current. At J the sky exceeds dark current by a factor of four, dominating the noise budget. The read noise (∼43 e−) falls below sky + dark noise for exposures of t > 7 s in Y and 3.5 s in J. We observed several representative science targets, including two supernovae, a z = 6.3 quasar, two local galaxies monitored for IR transients, and a galaxy cluster at z = 0.87. We observe a partial transit of the hot Jupiter HATS-34b, demonstrating the photometric stability to detect a 1.2% transit. A tiling of 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.
ISSN:	0004-6256 1538-3881 1538-3881