The MICADO first light imager for ELT: its astrometric performance

Pott, Jörg-Uwe; Rodeghiero, Gabriele; Riechert, Hannes; Massari, D.; Fabricius, Maximilian; Arcidiacono, Carmelo; Davies, Richard

doi:10.1117/12.2312069

Cited by 6 publications

(7 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Modern astrometry has in large part been possibly by an increasing understanding of the instrumental distortions and the stability thereof. 2,[14][15][16][17][18] The distortions shown in the previous section are relatively small, compared to the typical geometric distortions expected from the optical design and telescope stability. Furhermore, the shape of these distortion patterns can be resolved by a third order polynomial, 18 resulting in an astrometric solution accurate to 8 µas, with a minor improvement when using a fifth order polynomial.…”

Section: Discussionmentioning

confidence: 87%

“…The instrument will be able to determine the relative distance between multiple point sources to an accuracy of 50 microarcseconds (µas). 2 The main challenge for reaching such performance lies in the understanding of the system stability -how image distortions change as the telescopes moves around, temperature variations occur and time passes. In this work we investigate the impact of wavefront errors on the geometric distortions, and subsequently on the astrometric accuracy.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Fourier optics approach to evaluate the astrometric performance of MICADO

Born

Jellema

Navarro

et al. 2020

Modeling, Systems Engineering, and Project Management for Astronomy IX

View full text Add to dashboard Cite

We present our investigation into the impact of wavefront errors on high accuracy astrometry using Fourier Optics. MICADO, the upcoming near-IR imaging instrument for the Extremely Large Telescope, will offer capabilities for relative astrometry with an accuracy of 50 micro arcseconds (µas). Due to the large size of the point spread function (PSF) compared to the astrometric requirement, the detailed shape and position of the PSF on the detector must be well understood. Furthermore, because the atmospheric dispersion corrector of MICADO is a moving component within an otherwise mostly static instrument, it might not be sufficient to perform a simple pre-observation calibration. Therefore, we have built a Fourier Optics framework, allowing us to evaluate the small changes in the centroid position of the PSF as a function of wavefront error. For a complete evaluation, we model both the low order surface form errors, using Zernike polynomials, and the mid-and high-spatial frequencies, using Power Spectral Density analysis. The described work will then make it possible, performing full diffractive beam propagation, to assess the expected astrometric performance of MICADO.

show abstract

Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

A Fourier optics approach to evaluate the astrometric performance of MICADO

Born

Jellema

Navarro

et al. 2020

Modeling, Systems Engineering, and Project Management for Astronomy IX

View full text Add to dashboard Cite

show abstract

“…63 The requirements in regular imaging are 50 μas, with a goal of 20 μas. 68 This will be achieved thanks to a dedicated astrometric stability by design and built-in calibration strategy. However, high-precision astrometry in exoplanet imaging requires a dedicated strategy, as described in this paper using SPHERE as an example.…”

Section: Exoplanet Imaging With the Eltmentioning

confidence: 99%

Lessons learned from SPHERE for the astrometric strategy of the next generation of exoplanet imaging instruments

Maire

Langlois

Delorme

et al. 2021

J. Astron. Telesc. Instrum. Syst.

Self Cite

View full text Add to dashboard Cite

Measuring the orbits of directly imaged exoplanets requires precise astrometry at the milliarcsec level over long periods of time due to their wide separation to the stars (≳10 au) and long orbital period (≳20 yr). To reach this challenging goal, a specific strategy was implemented for the instrument Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE), the first dedicated exoplanet imaging instrument at the Very Large Telescope of the European Southern Observatory (ESO). A key part of this strategy relies on the astrometric stability of the instrument over time. We monitored for five years the evolution of the optical distortion, pixel scale, and orientation to the True North of SPHERE images using the near-infrared instrument IRDIS. We show that the instrument calibration achieves a positional stability of ∼1 mas over 2″ field of views. We also discuss the SPHERE astrometric strategy, issues encountered in the course of the on-sky operations, and lessons learned for the next generation of exoplanet imaging instruments on the Extremely Large Telescope being built by ESO. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

show abstract

“…As for this work, previous experience with the MCAO system at GeMS 17,47 has shown that the astrometric solution built within a single detector is systematically better and preferable to the global solution over the full detector array. These simulations do not include stability effects of the optomechanical tolerances that have a similar impact on the size of the correctable FoV (1 to 2 arc sec) as stated by Pott et al 16 The time-variant component of the distortions is represented here by the field rotation on top of the optics, which turns out to have a very similar amplitude and temporal behavior to the stability tolerances of the optics. The observation scenario shall be oriented toward the construction of local astrometric solutions over 2 arc sec 2 patches mosaicking larger fractions of the MICADO FoV or alternatively recalibrating the distortion pattern more frequently in the PA space when working on wider FoVs.…”

Section: This Distortion Study Concentrates On the Distorted Versus Distorted (Dd) Frames At Differentmentioning

confidence: 99%

“…For instruments such as MICADO 14 and IRIS, 15 the common figure of merit for the relative astrometry at single-and multi-epoch observations is 50 μas in the near-infrared (NIR) for sources ∼1 as apart. The origin and fundamental limits of achieving 50 μas-level astrometry with the ELT/MICADO was discussed by Pott et al 16 Generally, NIR refers to a wavelength range of 0.8 to 2.4 μm where typically higher AO performances (and boosted astrometry) are achieved at the red side of this range (H-K band). The ≃50 μas precision is intended as postfit, differential astrometry after having applied third to fifth or higher order polynomials that fit and remove the distortion pattern induced by the instrument to the image.…”

Section: Introductionmentioning

confidence: 99%

Performance and limitations of using ELT and MCAO for 50 μas astrometry

Rodeghiero

Arcidiacono

Pott

et al. 2021

J. Astron. Telesc. Instrum. Syst.

Self Cite

View full text Add to dashboard Cite

Multi-conjugated adaptive optics (MCAO) is essential for performing astrometry with the Extremely Large Telescope (ELT). Unlike most of the 8-m class telescopes, the ELT will be a fully adaptive telescope, and a significant portion of the adaptive optics (AO) dynamic range will be depleted by the correction and stabilization of the telescope aberrations and instabilities. MCAO systems are of particular interest for ground-based astrometry since they stabilize the low-order field distortions and transient plate scale instabilities, which originate from the telescope and in the instrument. All instruments have several optical elements relatively far away from the pupil that can potentially challenge the astrometric precision of the observations with their residual mid-spatial frequencies errors. Using a combined simulation of ray tracing and AO numerical codes, we assess the impact of these systematic errors at different field-ofview (FoV) scales and fitting scenarios. The distortions have been assessed at different sky position angles (PA) and indicate that over large FoVs only small PA ranges (AE1 deg to 3 deg) are accessible with astrometric residuals ≤50 μas. A full compliance with the astrometric requirement, at any PA, is achievable for 2 arc sec 2 FoV patches already with a third-order polynomial. The natural partition of the optical system into three segments, i.e., the ELT, the MAORY MCAO module, and the MICADO instrument, resembles a splitting of the astrometric problem into the three subsystems that are characterized by different distortion amplitudes and calibration strategies. The result is a family portrait of the different optical segments with their specifications, dynamic motions, conjugation height, and AO correctability, leading to tracing their role in the bigger puzzle of the 50-μas as astrometric endeavor. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

show abstract

The MICADO first light imager for ELT: its astrometric performance

Cited by 6 publications

References 7 publications

A Fourier optics approach to evaluate the astrometric performance of MICADO

A Fourier optics approach to evaluate the astrometric performance of MICADO

Lessons learned from SPHERE for the astrometric strategy of the next generation of exoplanet imaging instruments

Performance and limitations of using ELT and MCAO for 50 μas astrometry

Contact Info

Product

Resources

About