Design and performance of a Collimated Beam Projector for telescope transmission measurement using a broadband light source

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Auteurs principaux: Sommer, K., Cohen-Tanugi, J., Plez, B., Betoule, M., Bongard, S., Guillou, L. Le, Neveu, J., Nuss, E., Sepulveda, E., Souverin, T., Moniez, M., Stubbs, C. W.
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Publié: 2023
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author Sommer, K.
Cohen-Tanugi, J.
Plez, B.
Betoule, M.
Bongard, S.
Guillou, L. Le
Neveu, J.
Nuss, E.
Sepulveda, E.
Souverin, T.
Moniez, M.
Stubbs, C. W.
author_facet Sommer, K.
Cohen-Tanugi, J.
Plez, B.
Betoule, M.
Bongard, S.
Guillou, L. Le
Neveu, J.
Nuss, E.
Sepulveda, E.
Souverin, T.
Moniez, M.
Stubbs, C. W.
contents Type Ia supernovae are the most direct cosmological probe to study dark energy in the recent Universe, for which the photometric calibration of astronomical instruments remains one major source of systematic uncertainties. To address this, recent advancements introduce Collimated Beam Projectors (CBP), aiming to enhance calibration by precisely measuring a telescope's throughput as a function of wavelength. This work describes the performance of a prototype portable CBP. The experimental setup consists of a broadband Xenon light source replacing a more customary but much more demanding high-power laser source, coupled with a monochromator emitting light inside an integrating sphere monitored with a photodiode and a spectrograph. Light is injected at the focus of the CBP telescope projecting a collimated beam onto a solar cell whose quantum efficiency has been obtained by comparison with a NIST-calibrated photodiode. The throughput and signal-to-noise ratio achieved by comparing the photocurrent signal in the CBP photodiode to the one in the solar cell are computed. We prove that the prototype, in its current state of development, is capable of achieving 1.2 per cent and 2.3 per cent precision on the integrated g and r bands of the ZTF photometric filter system respectively, in a reasonable amount of integration time. Central wavelength determination accuracy is kept below $\sim$ {0.91} nm and $\sim$ {0.58} nm for g and r bands. The expected photometric uncertainty caused by filter throughput measurement is approximately 5 mmag on the zero-point magnitude. Several straightforward improvement paths are discussed to upgrade the current setup.
format Preprint
id arxiv_https___arxiv_org_abs_2312_02835
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Design and performance of a Collimated Beam Projector for telescope transmission measurement using a broadband light source
Sommer, K.
Cohen-Tanugi, J.
Plez, B.
Betoule, M.
Bongard, S.
Guillou, L. Le
Neveu, J.
Nuss, E.
Sepulveda, E.
Souverin, T.
Moniez, M.
Stubbs, C. W.
Instrumentation and Methods for Astrophysics
Type Ia supernovae are the most direct cosmological probe to study dark energy in the recent Universe, for which the photometric calibration of astronomical instruments remains one major source of systematic uncertainties. To address this, recent advancements introduce Collimated Beam Projectors (CBP), aiming to enhance calibration by precisely measuring a telescope's throughput as a function of wavelength. This work describes the performance of a prototype portable CBP. The experimental setup consists of a broadband Xenon light source replacing a more customary but much more demanding high-power laser source, coupled with a monochromator emitting light inside an integrating sphere monitored with a photodiode and a spectrograph. Light is injected at the focus of the CBP telescope projecting a collimated beam onto a solar cell whose quantum efficiency has been obtained by comparison with a NIST-calibrated photodiode. The throughput and signal-to-noise ratio achieved by comparing the photocurrent signal in the CBP photodiode to the one in the solar cell are computed. We prove that the prototype, in its current state of development, is capable of achieving 1.2 per cent and 2.3 per cent precision on the integrated g and r bands of the ZTF photometric filter system respectively, in a reasonable amount of integration time. Central wavelength determination accuracy is kept below $\sim$ {0.91} nm and $\sim$ {0.58} nm for g and r bands. The expected photometric uncertainty caused by filter throughput measurement is approximately 5 mmag on the zero-point magnitude. Several straightforward improvement paths are discussed to upgrade the current setup.
title Design and performance of a Collimated Beam Projector for telescope transmission measurement using a broadband light source
topic Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2312.02835