Pushing point-spread function reconstruction to the next level: application to SPHERE/ZIMPOL. Issue 1 (4th April 2020)

• Record Type: Journal Article
• Authors: Beltramo-Martin, O; Marasco, A; Fusco, T; Massari, D; Milli, J; Fiorentino, G; Neichel, B
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 494:Issue 1(2020)
• Page Start: 775
• Page End: 788
• Publication Date: 2020-04-04
• Subjects: atmospheric effects -- instrumentation: adaptive optics -- methods: analytical -- methods: data analysis; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa525
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Point-spread function (PSF) reconstruction (PSF-R) is a well-established technique to determine the PSF reliably and accurately from adaptive optics (AO) control-loop data. We have successfully applied this technique to improve the precision of photometry and astrometry for observations of NGC 6121 obtained with the Spectro Polarimetric High-contrast Exoplanet REsearch (SPHERE)/Zurich IMaging POLarimeter (ZIMPOL), which will be presented in a forthcoming Letter. First, we present the methodology we followed to reconstruct the PSF by combining pupil-plane and focal-plane measurements using our PSF-R method PRIME (PSF Reconstruction and Identification for Multiple-source characterization Enhancement), with upgrades of both the model and best-fitting steps compared with previous articles. Secondly, we highlight that PRIME allows us to maintain the PSF fitting residual below 0.2 per cent over 2 hours of observation and using only 30 s of AO telemetry, which may have important consequences for telemetry storage for PSF-R purposes on future 30–40 m class telescopes. Finally, we deploy PRIME in a more realistic regime using faint stars, so as to identify the precision needed on the initial-guess parameters to ensure convergence towards the optimal solution.