Microarcsecond astrometry with MCAO using a diffractive mask

S. Mark Ammons, Eduardo A. Bendek, Olivier Guyon, Bruce Macintosh, Dmitry Savransky

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Citation (Scopus)

Abstract

We present a new ground-based technique to detect or follow-up long-period, potentially habitable exoplanets via precise relative astrometry of host stars using Multi-Conjugate Adaptive Optics (MCAO) on 8 meter telescopes equipped with diffractive masks. MCAO improves relative astrometry both by cancellation of high-altitude atmospheric layers, which induce dynamic focal-plane distortions, and the improvement of centroiding precision with sharper PSFs. However, mass determination of habitable exoplanets requires multi-year reference grid stability of ~1-10 μas or nanometer-level stability on the long-term average of out-of-pupil phase errors, which is difficult to achieve with MCAO (e.g., Meyer et al. 2011). The diffractive pupil technique calibrates dynamic distortion via extended diffraction spikes generated by a dotted primary mirror, which are referenced against a grid of background stars (Guyon et al. 2012). The diffractive grid provides three benefits to relative astrometry: (1) increased dynamic range, permitting observation of V < 10 stars without saturation; (2) calibration of dynamic distortion; and (3) a spectrum of the target star, which can be used to calibrate the magnitude of differential atmospheric refraction to the microarcsecond level. A diffractive 8-meter telescope with diffraction-limited MCAO in K-band reaches < 3-5 μas relative astrometric error per coordinate perpendicular to the zenith vector in one hour on a bright target star in fields of moderate stellar density (~10-40 stars arcmin-2). We present preliminary on-sky results of a test of the diffractive mask on the Nickel telescope at Lick Observatory.

Original languageEnglish (US)
Title of host publicationProceedings of the International Astronomical Union
PublisherCambridge University Press
Pages369-374
Number of pages6
Volume8
EditionS293
ISBN (Print)9781107033825
DOIs
StatePublished - 2012

Publication series

NameProceedings of the International Astronomical Union
NumberS293
Volume8
ISSN (Print)17439213
ISSN (Electronic)17439221

Fingerprint

astrometry
adaptive optics
masks
stars
grids
telescopes
extrasolar planets
pupils
atmospheric refraction
phase error
zenith
high altitude
extremely high frequencies
diffraction
spikes
cancellation
dynamic range
sky
observatories
nickel

Keywords

  • astrometry
  • instrumentation: adaptive optics
  • stars: planetary systems
  • techniques:high angular resolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics

Cite this

Ammons, S. M., Bendek, E. A., Guyon, O., Macintosh, B., & Savransky, D. (2012). Microarcsecond astrometry with MCAO using a diffractive mask. In Proceedings of the International Astronomical Union (S293 ed., Vol. 8, pp. 369-374). (Proceedings of the International Astronomical Union; Vol. 8, No. S293). Cambridge University Press. https://doi.org/10.1017/S1743921313013173

Microarcsecond astrometry with MCAO using a diffractive mask. / Ammons, S. Mark; Bendek, Eduardo A.; Guyon, Olivier; Macintosh, Bruce; Savransky, Dmitry.

Proceedings of the International Astronomical Union. Vol. 8 S293. ed. Cambridge University Press, 2012. p. 369-374 (Proceedings of the International Astronomical Union; Vol. 8, No. S293).

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Ammons, SM, Bendek, EA, Guyon, O, Macintosh, B & Savransky, D 2012, Microarcsecond astrometry with MCAO using a diffractive mask. in Proceedings of the International Astronomical Union. S293 edn, vol. 8, Proceedings of the International Astronomical Union, no. S293, vol. 8, Cambridge University Press, pp. 369-374. https://doi.org/10.1017/S1743921313013173
Ammons SM, Bendek EA, Guyon O, Macintosh B, Savransky D. Microarcsecond astrometry with MCAO using a diffractive mask. In Proceedings of the International Astronomical Union. S293 ed. Vol. 8. Cambridge University Press. 2012. p. 369-374. (Proceedings of the International Astronomical Union; S293). https://doi.org/10.1017/S1743921313013173
Ammons, S. Mark ; Bendek, Eduardo A. ; Guyon, Olivier ; Macintosh, Bruce ; Savransky, Dmitry. / Microarcsecond astrometry with MCAO using a diffractive mask. Proceedings of the International Astronomical Union. Vol. 8 S293. ed. Cambridge University Press, 2012. pp. 369-374 (Proceedings of the International Astronomical Union; S293).
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