Information for applicants

  • Those who intend to use the LGS mode for the first time are encouraged to make contact with the support astronomer in advance.
  • Applicants who intend to use the LGS mode with PI type instruments (such as CHARIS/SCExAO), please make contact with the PI of the instrument and AO188 support astronomer.
  • There are some restrictions for observations that require using the atmospheric dispersion corrector for non-sidereal objects. Those who want to observe with this mode of operation should make contact with the support astronomer in advance.


Note: Please read Planning Observations carefully before submitting proposals.

AO188 is equipped with a 188-element wavefront curvature sensor with photon counting APD modules and a 188 element bimorph mirror. AO188 is installed at the IR Nasmyth platform of Subaru telescope, whereas our previous AO36 system was operated at the Cassegrain focus. This can be used in either natural guide star (NGS) or laser guide star (LGS) mode.

The open-use instrument operated with AO188 is IRCS. SCExAO, SCExAO+CHARIS, and SCExAO+HiCIAO are also available with AO188 as PI type instruments. AO188 has successfully completed the first light observations with IRCS in late 2006 (see the press release).

AO188 in the NGS mode has been offered for open use observations since S08B. For the NGS mode operation, a natural guide star is required. The guide star should be a bright star located within 30 arcsec of the science target. You can also use your target itself as the NGS. To obtain reasonable performance improvement, the NGS should be brighter than R magnitude of 16.5. Diffraction-limited spatial resolution can be achieved at KLM-band with a sufficiently bright guide star at good observing conditions. At shorter wavelength (zJH band), high spatial resolution comparable to or even higher than the K-band diffraction-limit resolution can be achieved. The maximum Strehl ratio so far achieved at K-band is 0.55 at a 0.5'' seeing condition.

As of the latter half of S11A semester, the LGS mode that uses an artificial sodium laser guide star for high-order wavefront correction will become available. The LGS can be propagated into the sky close to or on top of the science target. The brightness of the LGS is around 10.5 mag in R-band in best case. This brightness might become faint depending on the sodium layer condition and telescope elevation. A natural guide star is still required for the LGS mode operation to correct for the tip-tilt motion that cannot be sensed by the LGS. The tip-tilt guide star (TTGS) is expected to be brighter than 18 mag in R-band and located within around 90 arcsec from the science target. You might be able to get small correction with the guide star as faint as R~19 (only in dark night). The performance of the LGS mode is summarized in the performance page listed in below.

Previous AO36 system has been decommissioned since S08B semester and no longer available. If you need the information of AO36, please see old AO page.

Instrument citation

Please cite the following paper when you refer AO188 in your publication.

"Commisioning status of Subaru laser guide sta adaptive optics system"
Hayano et al. 2010, Proc. SPIE, vol. 7736, 21
"Current status of the laser guide star adaptive optics system for Subaru Telescope"
Hayano et al. 2008, Proc. SPIE, vol. 7015, 25

Further information

Questions regarding this page should be directed to Etsuko Mieda ( Please note that all numbers on these pages are subject to change as the performance of AO188 is better determined.

13 July 2017

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