Gaia: focus, straylight and basic angle

Mora, A.; Biermann, M.; Bombrun, A.; Boyadjian, J.; Chassat, F.; Corberand, P.; Davidson, M.; Doyle, Dominic; Escolar, D.; Gielesen, W.L.M.; Guilpain, T.; Kirschner, Volker; Koeck, C.; Laine, Benoit; Lindegren, L.; Serpell, Edmund; Tatry, Philippe; Thoral, P.

doi:10.1117/12.2230763

Cited by 16 publications

(11 citation statements)

References 6 publications

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“…It can also jeopardize the detection of faint objects such as exoplanets in the case of coronagraphs. The worst situation is if a SL issue is only discovered once the instrument is already in space, as it was the case for example in the GAIA mission 4 .…”

mentioning

confidence: 99%

Stray light characterization with ultrafast time-of-flight imaging

Clermont

Uhring

Georges

2021

Sci Rep

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Understanding stray light (SL) is a crucial aspect in the development of high-end optical instruments, for instance space telescopes. As it drives image quality, SL must be controlled by design and characterized experimentally. However, conventional SL characterization methods are limited as they do not provide information on its origins. The problem is complex due to the diversity of light interaction processes with surfaces, creating various SL contributors. Therefore, when SL level is higher than expected, it can be difficult to determine how to improve the system. We demonstrate a new approach, ultrafast time-of-flight SL characterization, where a pulsed laser source and a streak camera are used to record individually SL contributors which travel with a specific optical path length. Furthermore, the optical path length offers a means of identification to determine its origin. We demonstrate this method in an imaging system, measuring and identifying individual ghosts and scattering components. We then show how it can be used to reverse-engineer the instrument SL origins.

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mentioning

confidence: 99%

Stray light characterization with ultrafast time-of-flight imaging

Clermont

Uhring

Georges

2021

Sci Rep

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“…The Hipparcos catalog (ESA, 1997) is shown as a solid orange line for comparison, the integrated sky appearing slightly brighter until the catalog completeness falls off above m V ∼ 9. Newer catalogs such as Gaia (Mora et al, 2016) would provide increased precision but not discernibly alter the shape of the stellar density function for these relatively bright stars. Neglecting detector effects, integration over the distribution of stellar magnitudes (m), and the instrument field-of-view (FOV) give the total number of photons per second received by the detector from stars up to a limiting magnitude m l .…”

Section: Sensingmentioning

confidence: 99%

Practical Limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon Noise

Douglas¹,

Tracy

Manchester

2021

Front. Astron. Space Sci.

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Accurate and stable spacecraft pointing is a requirement of many astronomical observations. Pointing particularly challenges nanosatellites because of an unfavorable surface area–to-mass ratio and a proportionally large volume required for even the smallest attitude control systems. This work explores the limitations on astrophysical attitude knowledge and control in a regime unrestricted by actuator precision or actuator-induced disturbances such as jitter. The external disturbances on an archetypal 6U CubeSat are modeled, and the limiting sensing knowledge is calculated from the available stellar flux and grasp of a telescope within the available volume. These inputs are integrated using a model-predictive control scheme. For a simple test case at 1 Hz, with an 85-mm telescope and a single 11th magnitude star, the achievable body pointing is predicted to be 0.39 arcseconds. For a more general limit, integrating available star light, the achievable attitude sensing is approximately 1 milliarcsecond, which leads to a predicted body pointing accuracy of 20 milliarcseconds after application of the control model. These results show significant room for attitude sensing and control systems to improve before astrophysical and environmental limits are reached.

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“…The Hipparcos catalog ESA ( 1997) is shown as a solid orange line for comparison, the integrated sky appearing slightly brighter until the catalog completeness falls off above m V ∼ 9. Newer catalogs such as Gaia (Mora et al, 2016) would provide increased precision but not discernibly alter the shape of the stellar density function for these relative bright stars. Neglecting detector effects, integration over the distribution of stellar magnitudes (m) and the instrument field-of-view (FOV) gives the total number of photons per second received by the detector from stars up to a limiting magnitude m l .…”

Section: Sensingmentioning

confidence: 99%

Practical limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon Noise

Douglas,

Tracy,

Manchester

2021

Preprint

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Accurate and stable spacecraft pointing is a requirement of many astronomical observations. Pointing particularly challenges nanosatellites because of an unfavorable surface area to mass ratio and proportionally large volume required for even the smallest attitude control systems. This work explores the limitations on astrophysical attitude knowledge and control in a regime unrestricted by actuator precision or actuator-induced disturbances such as jitter. The external disturbances on an archetypal 6U CubeSat are modeled and the limiting sensing knowledge is calculated from the available stellar flux and grasp of a telescope within the available volume. These inputs are integrated using a model-predictive control scheme. For a simple test case at 1 Hz, with an 85 mm telescope and a single 11th magnitude star, the achievable body pointing is predicted to be 0.39 arcseconds. For a more general limit, integrating available star light, the achievable attitude sensing is approximately 1 milliarcsecond, which leads to a predicted body pointing accuracy of 20 milliarcseconds after application of the control model. These results show significant room for attitude sensing and control systems to improve before astrophysical and environmental limits are reached.

show abstract

Gaia: focus, straylight and basic angle

Cited by 16 publications

References 6 publications

Stray light characterization with ultrafast time-of-flight imaging

Stray light characterization with ultrafast time-of-flight imaging

Practical Limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon Noise

Practical limits on Nanosatellite Telescope Pointing: The Impact of Disturbances and Photon Noise

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