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A Brief Description:
MMTPol (Temporarily unavailable): NOTE: MMTPol is being upgraded while the MMT AO system is also undergoing an upgrade. The AO system will be available sometime in 2019.

MMTPol is a 1-5 µm diffraction-limited imaging polarimeter fed by the f/15 AO beam with negligible instrumental polarization. It was built at the Universities of Minnesota & Florida and commissioned at the MMT in November 2011.  It is a PI instrument. Contacts are Terry Jones and Chris Packham.  For instructions on how to propose to use MMTPol please see here.

The Fundamental Capabilities:



20" x 40"

Instrumental Polarization

0.05% +/-0.03%

FWHM at 2.2 µm with AO


SB Sensitivity

At 2.2 µm 18.1 mag/arcsec^2, S/N=3/1 in 2 hrs

SB Sensitivity

At 3.1 µm 15.9 mag/arcsec^2, S/N=3/1 in 2 hrs

Point Source Polarimetry

At 2.2 µm m=14.6, P=+/-1% in 2 hrs

Point Source Polarimetry

At 3.1 µm m=12.2, P=+/-1% in 2 hrs

Filters available:

  • 1.32 µm 3%
  • 2.20 µm 5%
  • 3.12 µm 4%
  • 3.50 µm 8%
  • 3.80 µm L'
  • 4.70 µm M
Further Information:

MMTPol is an adaptive optics optimized imaging polarimeter for use at the 6.5m MMT. By taking full advantage of the adaptive optics secondary mirror of the MMT, this polarimeter offers diffraction-limited polarimetry with very low instrumental polarization. The advent of AO secondary mirrors (e.g., Brusa et al. 2003) offers the chance to observe at the diffraction limit of large telescopes but with negligible increased instrumental polarization. The combination of a large collecting area, an AO system with no off-axis reflections, and an optical design approach to offer precision polarimetry, will permit polarimetric images in the 1-5μm region at higher precision at the diffraction limit than any other polarimeter.