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Testing of the LSST's photometric calibration strategy at the CTIO 0.9 meter telescope

Coughlin, Michael W. and Deustua, Susana and Guyonnet, Augustin and Mondrik, Nicholas and Rice, Joseph P. and Stubbs, Christopher W. and Woodward, John T. (2018) Testing of the LSST's photometric calibration strategy at the CTIO 0.9 meter telescope. In: Observatory Operations: Strategies, Processes, and Systems VII. Proceedings of SPIE. No.10704. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 1070420 . ISBN 9781510619616.

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The calibration hardware system of the Large Synoptic Survey Telescope (LSST) is designed to measure two quantities: a telescope's instrumental response function versus wavelength and atmospheric transmission. First of all, a "collimated beam projector," which projects monochromatic light, monitored with a NIST-traceable photodiode, through a mask and a collimating optic onto the telescope, is designed to measure the instrumental response function. This method does not suffer from stray light effects and the reflections/ghosting present when using a flat-field screen illumination, which has a systematic source of uncertainty from uncontrolled reflections. It allows for an independent measurement of the throughput of the telescope's optical train as well as each filter's transmission as a function of position on the primary mirror. Second, CALSPEC stars can be used as calibrated light sources to illuminate the atmosphere and measure its transmission. To produce spectrophotometry necessary to measure the atmosphere's transfer function, we use the telescope's imager with a Ronchi grating in place of a filter to configure it as a low resolution slitless spectrograph. In this paper, we describe this calibration strategy, focusing on results from this prototype system at the Cerro Tololo Inter-American Observatory (CTIO) 0.9 meter telescope. We compare the instrumental throughput measurements to nominal values from the vendor. We describe measurements of the atmosphere made via CALSPEC standard stars during the same run.

Item Type:Book Section
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URLURL TypeDescription Paper ItemIAU Conference Paper
Coughlin, Michael W.0000-0002-8262-2924
Stubbs, Christopher W.0000-0003-0347-1724
Additional Information:© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE). MC was supported by the David and Ellen Lee Postdoctoral Fellowship at the California Institute of Technology. CWS is grateful to the DOE Office of Science for their support under award DE-SC0007881. NM is supported by National Science Foundation Graduate Research Fellowship Program, under NSF grant number DGE 1745303. NM thanks the LSSTC Data Science Fellowship Program, his time as a Fellow has benefited this work.
Funding AgencyGrant Number
David and Ellen Lee Postdoctoral ScholarshipUNSPECIFIED
Department of Energy (DOE)DE-SC0007881
Large Synoptic Survey Telescope CorporationUNSPECIFIED
Subject Keywords:LSST, Photometric Calibration
Series Name:Proceedings of SPIE
Issue or Number:10704
Record Number:CaltechAUTHORS:20190102-155138988
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Official Citation:Michael W. Coughlin, Susana Deustua, Augustin Guyonnet, Nicholas Mondrik, Joseph P. Rice, Christopher W. Stubbs, John T. Woodward, "Testing of the LSST's photometric calibration strategy at the CTIO 0.9 meter telescope," Proc. SPIE 10704, Observatory Operations: Strategies, Processes, and Systems VII, 1070420 (10 July 2018); doi: 10.1117/12.2309582
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92011
Deposited By: George Porter
Deposited On:03 Jan 2019 22:01
Last Modified:16 Nov 2021 03:46

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