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

The calibration hardware system of the Large Synoptic Survey Telescope (LSST) is designed to measure two quantities: a telescope's instrumental response and atmospheric transmission, both as a function of wavelength. First of all, a "collimated beam projector" is designed to measure the instrumental response function by projecting monochromatic light through a mask and a collimating optic onto the telescope. During the measurement, the light level is monitored with a NIST-traceable photodiode. This method does not suffer from stray light effects or the reflections (known as 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 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 a prototype system at the Cerro Tololo Inter-American Observatory (CTIO) 0.9 meter telescope. We compare the instrumental throughput measurements to nominal values measured using a laboratory spectrophotometer, and we describe measurements of the atmosphere made via CALSPEC standard stars during the same run

Le projet SNDICE : réalisation d'un dispositif optoélectronique pour l'étalonnage photométrique de l'imageur grand champ MegaCam au CFHT

The photometric calibration of the wide field imager MegaCam at the CFHTis the dominant systematic uncertainty for the measurement of the cosmological parameters with type Ia supernovae performed by the SNLS team.This thesis descibes the SNDICE project, an illumination source made of 24 LEDsaiming at characterizing at the permil level the response of MegaCam to an illumination. The device has been constructed and characterized at the LPNHE prior to being installed at the CFHT.The first part of the manuscript describes the spectro-photometric calibration of SNDICE. It shows the high stability of the source and discuss in detail the various systematics of the calibration. The second part describes the analysis of in-situ illuminations of MegaCam with SNDICE. The analysis emphasises on its specificities : an highly stable, partial illumination of the primary miror which allow unique study of reflections on the optics and monitoring of MegaCam electronic stability.La calibration photométrique de l'imageur grand champ MegaCam au Canada-France-Hawaii-telescope (CFHT) est l'incertitude systématique principale de la mesure des paramètres cosmologiques à l'aide des supernovae de type Ia qui a été effectuée par l'équipe SNLS.Cette thèse décrit le projet SNDICE, la réalisation en laboratoire et l'utilisation au télescope d'une source lumineuse constituée de 24 LEDs pour caractériser au pour mille la réponse de l'imageur MegaCam à une illumination.La première partie de ce manuscrit présente l'étalonnage photométrique de SNDICE. Il décrit l'excellente stabilité de la source et discute en détail les différentes systématiques. La seconde partie décrit l'analyse des images SNDICE prises par MegaCam. Cette analyse porte plus particulièrement sur les spécificités des illuminations SNDICE: l'illumination partielle du miroir par une source stable à 10-4, ce qui permet une étude unique des reflets sur les éléments optique du télescope et le suivi de la stabilité de l'électronique de MegaCam.umé disponibl

Le projet SNDICE (réalisation d'un dispositif optoélectronique pour l'étalonnage photométrique de l'imageur Grand Champ MegaCam au CFHT)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

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

AbstractThe calibration hardware system of the Large Synoptic Survey Telescope (LSST) is designed to measure two quantities: a telescope’s instrumental response and atmospheric transmission, both as a function of wavelength. First of all, a “collimated beam projector” is designed to measure the instrumental response function by projecting monochromatic light through a mask and a collimating optic onto the telescope. During the measurement, the light level is monitored with a NIST-traceable photodiode. This method does not suffer from stray light effects or the reflections (known as 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 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 a prototype system at the Cerro Tololo Inter-American Observatory (CTIO) 0.9 meter telescope. We compare the instrumental throughput measurements to nominal values measured using a laboratory spectrophotometer, and we describe measurements of the atmosphere made via CALSPEC standard stars during the same run.</jats:p

Electro-optical testing of fully depleted CCD image sensors for the Large Synoptic Survey Telescope camera

The LSST Camera science sensor array will incorporate 189 large format Charge Coupled Device (CCD) image sensors. Each CCD will include over 16 million pixels and will be divided into 16 equally sized segments and each segment will be read through a separate output amplifier. The science goals of the project require CCD sensors with state of the art performance in many aspects. The broad survey wavelength coverage requires fully depleted, 100 micrometer thick, high resistivity, bulk silicon as the imager substrate. Image quality requirements place strict limits on the image degradation that may be caused by sensor effects: optical, electronic, and mechanical. In this paper we discuss the design of the prototype sensors, the hardware and software that has been used to perform electro-optic testing of the sensors, and a selection of the results of the testing to date. The architectural features that lead to internal electrostatic fields, the various effects on charge collection and transport that are caused by them, including charge diffusion and redistribution, effects on delivered PSF, and potential impacts on delivered science data quality are addressed.Physic