Adaptive Optics System

For natural guide star observing, wavefronts may be corrected at full speed for objects of V ~ 11-12 magnitude, depending on conditions. For target stars as faint as V ~ 13.5-14, fewer corrections can be applied, but improvements in image quality over the natural seeing are possible. 

If the target star is fainter than V~14 you may choose one of the following options.

1. Leave the mirror flat and do no corrections.

2. Use a very nearby (less than 20-30 arcseconds away) brighter star to correct on.

3. Close the loop on a nearby bright star and "fix" the shape of the mirror, then return to the target star.  Keep the mirror stationary for the duration of the science observations.

Further Information:

When the f/15 is mounted the wind constraints are tighter to protect the deformable secondary mirror. If pointing into the wind and the wind is sustained at 25 mph or gusting above 30 mph, then we must close. If pointing away from the wind and the wind is sustained at 30 mph or gusting above 35 mph, the front shutters must be closed. Additionally, if the wind is coming out of the North-East or East, then it arrives at the telescope over Mt Wrightson and the ridge. This causes major turbulence above the telescope and will degrade the seeing and make it highly variable. In this case, there is nothing we can do to improve the conditions other than wait for the wind to change direction.

Overhead for setting up AO at the beginning of the night is estimated to be 30 minutes, with an additional 15 minutes for each new object during the night. Please include this in overhead estimates when planning your run.

For additional information on the MMT NGS-AO system performance see: "MMT AO Performance: Analysis and Status."

For a presentation of early science results, click here.

For more information, please contact adaptive optics scientist and engineer Keith Powell.

ARIES

Please Note that the LM band capabilities are not available currently. A large format 1-5 um detector is expected to be available in the future.

The Arizona Infrared imager and Echelle Spectrograph is designed to exploit the low thermal background and high optical throughput offered by the MMT's f/15 adaptive secondary system. With first imaging light achieved in 2003 and first spectra in 2007, ARIES is currently offered as a PI instrument. With three IR arrays, ARIES provides diffraction-limited imaging in the JHK(LM) atmospheric windows and long-slit and echelle spectroscopy at resolving powers from 1,500 to 50,000 (200 to 5 km/s). ARIES can also supply global wavefront tip/tilt information to the adaptive system using cryogenic pick-off mirrors to access field stars over a 90 arcsec diameter field at wavelengths from 1-2 microns.

ARIES consists of two dewars which share a common mount and vacuum. The 'purple dewar' is generally referenced as the imaging half of ARIES and also provides the spectrometer foreoptics. The 'green dewar' is generally referenced as the spectrometer half of ARIES. There is some cross-functionality between the two dewars: the imager contains a filter wheel that can provide slitless objective grism capabilities, and the spectrometer in turn has a grating selection mirror that can reference a flat mirror for wider field imaging.

To a greater or lesser degree, both halves of ARIES can be operated independently and simultaneously. Spectra of the science target can be acquired with the 'green' spectrometer while the spilt light in the slit plane can be imaged using the 'purple' camera.

Be aware that if you are applying to observe transits or obtain other time sensitive measurements with ARIES, it is unlikely that the instrument will be mounted at any time other than bright time. Please check whether your dates coincide with a bright moon phase before applying for time.

For further information please see the ARIES wiki.

BINOSPEC

Information for Binospec observers and instrument characteristics are described here.

Binospec will exploit the wide field of view of the MMT with the f/5 secondary mirror by using dual identical but independent channels splitting the focal plane into two 8' x 15' FOV. Each channel has up to 4 gratings, 6 filters and a 4K E2V CCD (0.24" pixel sampling). The commissioning filters will offer broadband Sloan g, r, i, z

For further information please see BINOSPEC webpages or contact Dan Fabricant.

BLINC / MIRAC

The Mid-Infrared Array Camera and Bracewell Infrared Nulling Cryostat (MIRAC-BLINC) is an instrument developed for use with the adaptive optics system on the 6.5 m MMT. It has two main modes of operation: imaging at 8-25 microns, and nulling interferometry at 8-13 microns.

A fourth version of MIRAC (MIRAC4) saw first light in late October 2006. The camera features a 256×256 array with high quantum efficiency and low dark current. The camera is cooled using a pulse tube mechanical cooler which eliminates the need for liquid helium cooling. BLINC is a liquid nitrogen-cooled set of fore-optics for the MIRAC system.

The entrance window provides the reflection surface for the visible light to be sent to the AO wavefront sensor. The Cassegrain focus is reimaged by an off-axis ellipse within BLINC which is capable of being rotated to send the light to either the nulling interferometer or the imaging channel. The imaging channel forms an image of the secondary on a reflective cold stop which baffles out warm radiation from the telescope. The mirror at the cold stop is mounted on a rotating voice coil actuator. This allows chopping at 1-10 Hz within the cryostat.

The nulling interferometer splits the entrance pupil in half and overlaps these two beams on a 50% transmissive beamsplitter. Manual alignment of the beams can be achieved with feedthrough actuators. Pathlength changes are introduced by translating the beamsplitter mount using a stepper motor with 42 microns of motion per revolution. Small pathlength changes can be introduced by a PZT-mounted mirror in the right arm of the interferometer. Both outputs of the interferometer are sent to a NICMOS3 detector within BLINC to allow sensing of phase variations in the interferometer. One of the outputs has a short pass dichroic which sends 8-13 micron light to MIRAC.

For further information please see the MIRAC-BLINC wiki.

Blue & Red Channel Spectrographs

Please follow the Blue and Red Channel links below to see tables of the fundamental capabilities.

For hints and tips on how to operate the instrument please see the Cheat Sheets.

CLIO

Clio is a 3-5 micron imager and coronagraph built to exploit the unique sensitivity and resolution of the MMT deformable secondary AO system. A particular area of focus for the instrument is to provide sensitive detection of giant planets at 3.8 and 4.8 microns. In spring 2010, the original 320×256 Indigo Systems InSb detector was replaced by a 512×1024 HAWAII HgCdTe detector. This upgrade allowed for more sensitive low background observations, while modestly reducing the allowable field size at M band.

For further information please see the CLIO wiki.

Hectospec & Hectochelle

Hectospec and Hectochelle are two large bench mounted spectrographs that are fiber fed by 300, 25m long optical fibers from the telescope's Cassegrain focus. A common to both spectrographs robotic positioner that is mounted behind the f/5 beam uses a pair of six-axis robots, dubbed Fred and Ginger, to reconfigure all 300 fibers over the 1deg focal surface to an accuracy of ~25um in just 300 seconds. Each fiber that is held magnetically on the focal surface has a core diameter of 250um that subtends to 1.5" on the sky. Adjacent fibers can be spaced as closely as 20" and is positioned using a complex algorithm.

Hectospec is a moderate-resolution, multiobject optical spectrograph, it offers 5770Å of spectral coverage at ~6Å resolution in the 350 to 1000 nm band. A higher dispersion grating offering ~3Å resolution is also available.

The Hectochelle adds a high dispersion capability to Hectospec's moderate dispersion with a second, very large bench-mounted spectrograph using an echelle grating. Hectochelle uses 240 of the possible 300 fibers and attains R~32,000 (sigma~4 km/s) over a single, filter-selected orders.

For greater details about the instruments, how to prepare for your observations, your reponsibilites, tips on data collection and reduction and links to all supporting documentation please see the Hectospec webpages and the Hectochelle webpages.  IDL Software for the reduction of Hectospec data can be found here (please contract Joannah Hinz with any questions).

MAESTRO

MAESTRO (The MMT Advanced Echelle Spectrograph) is a Cassegrain mounted, optical, slit single, high-resolution echelle spectrograph which uses the MMT f/5 secondary, spectroscopic corrector, wavefront sensor and ADC. MAESTRO has a 4096 x 4096 CCD with 15μm pixels that has been optimized for the UV by the UA Imaging Technology Lab (ITL).

The design of MAESTRO was driven by the desire to do multi-order spectroscopy of a single object with a wide wavelength coverage extending to the atmospheric cut-off in the UV. It is optimized for multi-order, simultaneous wavelength coverage, with R = 28,000, or 7.5 km/s when used with a 0.7" slit. The best possible spectral resolution, using a 0.3" slit, is Nyquist sampled with spectral resolution of R=93,000 or 3.2 km/s. The single exposure wavelength coverage is 3150 to 9850Å with small gaps redward of about 8000Å.

For further details please see the MAESTRO homepage.

MMIRS

MMIRS has returned from Magellan and now resides permanently at the MMT.  MMIRS observing is run in queue mode. Astronomers do not need to be present at the MMT for their observations. If you have questions about queue observing, please contact Joannah Hinz.

• Observing Manual
• Observing protocol -- Methodology required in order to obtain the best possible data reduction with the MMIRS Spectral Data Pipeline
• MMIRS Data Reduction Pipeline
• Slitmask design
• MMIRS Catalog Submission Tool -- The catalog submission tool provides the needed details to observatory staff to obtain your observations in queue mode. You should receive an email with a personalized link for your program.
• How to set up dither files for imaging

Getting Your Data:

Raw data can be obtained by emailing the SAO Telescope Data Center helpdesk.

MMTPol

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

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.

Megacam

PISCES

PISCES is a JHK wide field imager that was initially designed and built as a test bed for a Hawaii-I detector and used in conjunction with the f/9 secondary and was later used with the adaptive f/15. PISCES can reimage the focal plane from any telescope with an f-ratio #9 onto the 1024 x 1024 Hawaii CCD. It uses accurate pupil reimaging and cold baffling to block the thermally emissive structures associated with operating at the Cassegrain focus. The optical design was driven by the desire to optimize the spot sizes for the K band but also seeing-limited performance in the J and H bands.

For further information please see the PISCES webpages.

SPOL

SPOL is an imaging spectropolarimeter that can be configured with either a λ/2 or λ/4 rotatable achromatic retardation plate to provide linear or circular polarization measurements, respectively. A thin Wollaston prism, which has very high throughput and polarimetric efficiency, is used as the polarization analyzer. In spectroscopic mode a number of slit widths and gratings are available.  For the imaging mode, a large square 19" x 19" aperture is used and a flat mirror replaces the grating. The two polarized beams that emerge from the prism are reimaged as either complementary parallel spectra (spectroscopic mode) or complementary polarized images (imaging mode) on the CCD detector. The polarimetric efficiency (the degree of polarization measured for a completely polarized source) exceed 95% over a range of 4500-8000Å.

The instrument and camera are controlled with a single PC that is programmed to coordinate motion control (shutters, wave plates, etc) and image acquisition. The aperture plate is tilted to provide reimaging to a CCD guide camera for target acquisition and guiding.

An "observation" is the measurement of a Stokes parameter in a sequence of exposures, with polarimetric modulation occurring following readout via rotation of the wave plate. Individual frames are co-added in computer memory according to wave plate orientation, producing two complementary images in orthogonal senses of polarization. These are compared during data reduction to obtain the degree of polarization Q, U, or V.

Data reduction is performed using custom IRAF scripts that are available from the PI. These scripts are comprehensive and straight forward to use and therefore non-polarimetrists can achieve robust results. For information please see the SPOL website. 

SWIRC

The SAO Widefield InfraRed Camera (SWIRC) was designed with the goal to be a quickly delivered, wide FOV IR imager with minimum optical elements to give the MMT YJH ability with very high throughput. The instrument was proposed in May 2003 and successfully commissioned at the MMT just over 12 months later. The only trade-off for speed of completion was to sacrifice K-band capability by not including an internal, cold Lyot stop. The instrument is mounted at the f/5 focus without the imaging corrector optics as the dewar window acts as the field flattening lens. SWIRC has three science filters and one dark slide giving it an observing range of ~0.9μm to ~1.8μm. The instrument uses a 2048 x 2048 Hawaii-II detector with a plate scale of 0.15”/pixel to fully sample the best seeing at the MMT site over the 5.12’ x 5.12’ FOV.

For further details please the SWIRC website

MMTCam

MMTCam is an instrument for the MMT commissioned by Warren Brown in November 2012. The f/5 wavefront sensor system serves as the platform on which the imager is installed. The associated filters have central wavelengths of 355nm, 469nm, 616nm, 748nm, and 893nm. Binning can be set to 2 x 2 if faster read-out is desired. Because the f/5 secondary is mounted on the MMT for approximately 30% of available telescope time, the MMTCam enables a rapid-response imaging capability for the MMT for use on targets of opportunity, transients and monitoring of objects such as supernovae for longer term projects, without requiring an instrument change. We highly recommend requesting only dark or grey time with this instrument. For more information, including camera manual, please go here.