- Announcements
- enewscast
- Library
- PIO
- Sciops
- Gemini Home
- Telescopes and Sites
- Science Visitors at Gemini
- Observing With Gemini
- Instruments
- Retired Instruments
- NORTH
- ALTAIR
- GMOS
- GNIRS
- NIFS
- NIRI
- GRACES
- SOUTH
- FLAMINGOS-2
- GeMS
- GMOS
- GPI
- GSAOI
- VISITING
- Interface Specs for VI
- Visiting Instrument Policy
- DSSI Speckle Camera
- TEXES (North)
- RESOURCES
- Integration Time Calculators
- Magnitudes and Fluxes
- Near-IR Resources
- Mid-IR Resources
- Observing Condition Constraints
- Performance Monitoring
- SV/Demo Science

- Future Instrumentation & Current Development
- Queue and Schedules
- Data and Results
- Helpdesk
- Statistics

- Viaje

Change page style:

# Adaptive Optics in the ITC

The ability of the AO system to correct the wavefront depends on the brightness and off-axis angle of the wavefront reference source (the AO "guide star"). The Strehl ratio of the AO-corrected core is approximated in the ITC by:

where *S _{fit}* is the Strehl due to the system fitting error (i.e. limited number of actuators),

*S*is the Strehl loss due to the limited number of photons from the guide star and

_{noise}*S*is the Strehl loss due to anisoplantism.

_{aniso}*R*is the R-band guide star magnitude and

_{GS}*theta*is the off-axis angle in arcsec.

_{GS}The total signal from a point source is the sum of the AO-corrected core and the uncorrected (seeing-limited) halo. For moderate or high Strehl ratios the core dominates, for poor correction (low Strehl) the halo dominates. As in the non-AO case, the ITC defaults to an "optimum" aperture which gives a reasonable approximation of the best S/N ratio; we have taken this to be *1.18 * FWHM _{AO}*, where

*FWHM*is the width of the corrected core:

_{AO}

*Last update August 29, 2003; Francois Rigaut and Phil Puxley*