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J. Burkle (Wheaton College and Indiana University), S.L. Mufson (Indiana University)
This R&D project was designed to explore the possibility of calibrating fundamental stars for SNAP in the near infrared from the ground in select narrow bandpasses by comparing stellar photometric observations to a stable, calibrated light source. The test measurements were made with a single channel photometer equipped with a thermoelectrically-cooled Hamamatsu InGaAs detector attached to an 8-inch Meade telescope. The calibrated light source was a 40 watt lamp regulated by a DC power supply purchased from Oriel. The narrow-band (10 nm) interference filters were also obtained from Oriel. The key filter used in this experiment was centered at 1,050 nm, a band that is free of water vapor opacity. The project consisted of two experiments. First, laboratory measurements of the lamp source were made over a baseline of 8 meters to test the 1/r2 dependence of our setup in a dry, thermally stable environment; these measurements were compared with 1/r2 measurements over an unobstructed distance of 125 meters from the roof of the physics/astronomy building to the roof of the law school. The experiment used both the 1,050 nm filter and a second 1,200 nm filter, a band which is contaminated with large water vapor opacity. This experiment tested whether the 1/r2-law holds for the calibration lamp source in the water-free 1,050 nm band far enough away so that the lamp mimics a star. Second, the moon was followed as a function of hour angle in both the 1,050 nm and 1,200 nm bands to test whether highly accurate stellar calibration measurements can be made in narrow clear bandpasses in the near infrared. Results of these experiments will be presented.
This research was carried out through the Research Experience for Undergraduates program at Indiana University Bloomington. Support from the National Science Foundation through AST-0139617 is gratefully acknowledged.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.