Measurement of telescope transmission using a Collimated Beam Projector

International audienceThe number of type Ia supernova observations will see a significant growth within the next decade, especially thanks to the Legacy Survey of Space and Time undertaken by the Vera Rubin Observatory in Chile. With this rise, the statistical uncertainties will decrease and the flux calibration will become the main uncertainty for the characterization of dark energy. The uncertainty over the telescope transmission is a major systematic when measuring SNe Ia colors. Here we introduce the Collimated Beam Projector (CBP), a device that can measure the transmission of a telescope and its filters. Composed of a tunable monochromatic light source and optics to provide a parallel output beam this device is able to measure with high precision the filter transmissions. In the following, we will show how measuring precisely a telescope transmission can also improve the precision of the dark energy parameters. As an example, we will present the first results of the CBP in the context of the StarDice experiment

Measurement of telescope transmission using a Collimated Beam Projector

International audienceThe number of type Ia supernova observations will see a significant growth within the next decade, especially thanks to the Legacy Survey of Space and Time undertaken by the Vera Rubin Observatory in Chile. With this rise, the statistical uncertainties will decrease and the flux calibration will become the main uncertainty for the characterization of dark energy. The uncertainty over the telescope transmission is a major systematic when measuring SNe Ia colors. Here we introduce the Collimated Beam Projector (CBP), a device that can measure the transmission of a telescope and its filters. Composed of a tunable monochromatic light source and optics to provide a parallel output beam this device is able to measure with high precision the filter transmissions. In the following, we will show how measuring precisely a telescope transmission can also improve the precision of the dark energy parameters. As an example, we will present the first results of the CBP in the context of the StarDice experiment

StarDICE I: sensor calibration bench and absolute photometric calibration of a Sony IMX411 sensor

The Hubble diagram of type-Ia supernovae (SNe-Ia) provides cosmological constraints on the nature of dark energy with an accuracy limited by the flux calibration of currently available spectrophotometric standards. The StarDICE experiment aims at establishing a 5-stage metrology chain from NIST photodiodes to stars, with a targeted accuracy of \SI1{mmag} in $griz$ colors. We present the first two stages, resulting in the calibration transfer from NIST photodiodes to a demonstration \SI{150}{Mpixel} CMOS sensor (Sony IMX411ALR as implemented in the QHY411M camera by QHYCCD). As a side-product, we provide full characterization of this camera. A fully automated spectrophotometric bench is built to perform the calibration transfer. The sensor readout electronics is studied using thousands of flat-field images from which we derive stability, high resolution photon transfer curves and estimates of the individual pixel gain. The sensor quantum efficiency is then measured relative to a NIST-calibrated photodiode. Flat-field scans at 16 different wavelengths are used to build maps of the sensor response. We demonstrate statistical uncertainty on quantum efficiency below \SI{0.001}{e^-/γ} between \SI{387}{nm} and \SI{950}{nm}. Systematic uncertainties in the bench optics are controlled at the level of \SI{1e-3}{e^-/γ}. Uncertainty in the overall normalization of the QE curve is 1%. Regarding the camera we demonstrate stability in steady state conditions at the level of \SI{32.5}{ppm}. Homogeneity in the response is below \SI1{\percent} RMS across the entire sensor area. Quantum efficiency stays above \SI{50}{\percent} in most of the visible range, peaking well above \SI{80}{\percent} between \SI{440}{nm} and \SI{570}{nm}. Differential non-linearities at the level of \SI1{\percent} are detected. A simple 2-parameter model is proposed to mitigate the effect

StarDICE I: sensor calibration bench and absolute photometric calibration of a Sony IMX411 sensor

The Hubble diagram of type-Ia supernovae (SNe-Ia) provides cosmological constraints on the nature of dark energy with an accuracy limited by the flux calibration of currently available spectrophotometric standards. The StarDICE experiment aims at establishing a 5-stage metrology chain from NIST photodiodes to stars, with a targeted accuracy of \SI1{mmag} in $griz$ colors. We present the first two stages, resulting in the calibration transfer from NIST photodiodes to a demonstration \SI{150}{Mpixel} CMOS sensor (Sony IMX411ALR as implemented in the QHY411M camera by QHYCCD). As a side-product, we provide full characterization of this camera. A fully automated spectrophotometric bench is built to perform the calibration transfer. The sensor readout electronics is studied using thousands of flat-field images from which we derive stability, high resolution photon transfer curves and estimates of the individual pixel gain. The sensor quantum efficiency is then measured relative to a NIST-calibrated photodiode. Flat-field scans at 16 different wavelengths are used to build maps of the sensor response. We demonstrate statistical uncertainty on quantum efficiency below \SI{0.001}{e^-/γ} between \SI{387}{nm} and \SI{950}{nm}. Systematic uncertainties in the bench optics are controlled at the level of \SI{1e-3}{e^-/γ}. Uncertainty in the overall normalization of the QE curve is 1%. Regarding the camera we demonstrate stability in steady state conditions at the level of \SI{32.5}{ppm}. Homogeneity in the response is below \SI1{\percent} RMS across the entire sensor area. Quantum efficiency stays above \SI{50}{\percent} in most of the visible range, peaking well above \SI{80}{\percent} between \SI{440}{nm} and \SI{570}{nm}. Differential non-linearities at the level of \SI1{\percent} are detected. A simple 2-parameter model is proposed to mitigate the effect

StarDICE I: sensor calibration bench and absolute photometric calibration of a Sony IMX411 sensor

The Hubble diagram of type-Ia supernovae (SNe-Ia) provides cosmological constraints on the nature of dark energy with an accuracy limited by the flux calibration of currently available spectrophotometric standards. The StarDICE experiment aims at establishing a 5-stage metrology chain from NIST photodiodes to stars, with a targeted accuracy of \SI1{mmag} in $griz$ colors. We present the first two stages, resulting in the calibration transfer from NIST photodiodes to a demonstration \SI{150}{Mpixel} CMOS sensor (Sony IMX411ALR as implemented in the QHY411M camera by QHYCCD). As a side-product, we provide full characterization of this camera. A fully automated spectrophotometric bench is built to perform the calibration transfer. The sensor readout electronics is studied using thousands of flat-field images from which we derive stability, high resolution photon transfer curves and estimates of the individual pixel gain. The sensor quantum efficiency is then measured relative to a NIST-calibrated photodiode. Flat-field scans at 16 different wavelengths are used to build maps of the sensor response. We demonstrate statistical uncertainty on quantum efficiency below \SI{0.001}{e^-/γ} between \SI{387}{nm} and \SI{950}{nm}. Systematic uncertainties in the bench optics are controlled at the level of \SI{1e-3}{e^-/γ}. Uncertainty in the overall normalization of the QE curve is 1%. Regarding the camera we demonstrate stability in steady state conditions at the level of \SI{32.5}{ppm}. Homogeneity in the response is below \SI1{\percent} RMS across the entire sensor area. Quantum efficiency stays above \SI{50}{\percent} in most of the visible range, peaking well above \SI{80}{\percent} between \SI{440}{nm} and \SI{570}{nm}. Differential non-linearities at the level of \SI1{\percent} are detected. A simple 2-parameter model is proposed to mitigate the effect

Measurement of telescope transmission using a Collimated Beam Projector

International audienceThe number of type Ia supernova observations will see a significant growth within the next decade, especially thanks to the Legacy Survey of Space and Time undertaken by the Vera Rubin Observatory in Chile. With this rise, the statistical uncertainties will decrease and the flux calibration will become the main uncertainty for the characterization of dark energy. The uncertainty over the telescope transmission is a major systematic when measuring SNe Ia colors. Here we introduce the Collimated Beam Projector (CBP), a device that can measure the transmission of a telescope and its filters. Composed of a tunable monochromatic light source and optics to provide a parallel output beam this device is able to measure with high precision the filter transmissions. In the following, we will show how measuring precisely a telescope transmission can also improve the precision of the dark energy parameters. As an example, we will present the first results of the CBP in the context of the StarDice experiment

Measurement of telescope transmission using a Collimated Beam Projector

International audienceThe number of type Ia supernova observations will see a significant growth within the next decade, especially thanks to the Legacy Survey of Space and Time undertaken by the Vera Rubin Observatory in Chile. With this rise, the statistical uncertainties will decrease and the flux calibration will become the main uncertainty for the characterization of dark energy. The uncertainty over the telescope transmission is a major systematic when measuring SNe Ia colors. Here we introduce the Collimated Beam Projector (CBP), a device that can measure the transmission of a telescope and its filters. Composed of a tunable monochromatic light source and optics to provide a parallel output beam this device is able to measure with high precision the filter transmissions. In the following, we will show how measuring precisely a telescope transmission can also improve the precision of the dark energy parameters. As an example, we will present the first results of the CBP in the context of the StarDice experiment

StarDICE I: sensor calibration bench and absolute photometric calibration of a Sony IMX411 sensor

The Hubble diagram of type-Ia supernovae (SNe-Ia) provides cosmological constraints on the nature of dark energy with an accuracy limited by the flux calibration of currently available spectrophotometric standards. The StarDICE experiment aims at establishing a 5-stage metrology chain from NIST photodiodes to stars, with a targeted accuracy of \SI1{mmag} in $griz$ colors. We present the first two stages, resulting in the calibration transfer from NIST photodiodes to a demonstration \SI{150}{Mpixel} CMOS sensor (Sony IMX411ALR as implemented in the QHY411M camera by QHYCCD). As a side-product, we provide full characterization of this camera. A fully automated spectrophotometric bench is built to perform the calibration transfer. The sensor readout electronics is studied using thousands of flat-field images from which we derive stability, high resolution photon transfer curves and estimates of the individual pixel gain. The sensor quantum efficiency is then measured relative to a NIST-calibrated photodiode. Flat-field scans at 16 different wavelengths are used to build maps of the sensor response. We demonstrate statistical uncertainty on quantum efficiency below \SI{0.001}{e^-/γ} between \SI{387}{nm} and \SI{950}{nm}. Systematic uncertainties in the bench optics are controlled at the level of \SI{1e-3}{e^-/γ}. Uncertainty in the overall normalization of the QE curve is 1%. Regarding the camera we demonstrate stability in steady state conditions at the level of \SI{32.5}{ppm}. Homogeneity in the response is below \SI1{\percent} RMS across the entire sensor area. Quantum efficiency stays above \SI{50}{\percent} in most of the visible range, peaking well above \SI{80}{\percent} between \SI{440}{nm} and \SI{570}{nm}. Differential non-linearities at the level of \SI1{\percent} are detected. A simple 2-parameter model is proposed to mitigate the effect