Binospec - Next Generation Optical Spectrograph for the MMT

Daniel Fabricant, Robert Fata, Mark Mueller, Jack Barberis, Tom Gauron, and John Roll

Binospec at a Glance

• Dual beams address adjacent 8′ by 15′ fields of view (30′ total slit length)

• 3900 to 10000 Å spectral coverage

• Spectral resolution ~1300 – 5000 with 1″ wide slit

• Sampling is 0.22″/pixel on 4K by 4K array

Binospec vs. the World

Spectrograph Field of View (spectroscopy)

Maximum Spectral Resolution

Binospec-MMT 240 sq arcmin ~5000

DEIMOS-Keck 80 sq arcmin ~5000

VIMOS-VLT 224 sq arcmin ~2500

IMACS- Magellan 120 sq arcmin

>500 sq arcmin

>5000

<2500

Scientific Drivers for Binospec

Large scale structure and galaxy evolution from z=0-1.4 with [OII]3727 and z=2.2-7 with Ly α

Ly α at z~5.85.5 hrs with DEIMOS

9 i’ dropouts in 200 sqarcmin GOODS-N field

New Scientific Possibilities with Binospec

• Perform slitless spectroscopy to identify PN in nearby galaxies and conduct dynamical studies

• Characterize faint Chandra/Spitzer AGN samples beyond reach of Hectospec

• Efficiently observe crowded fields that do not use 1º Hectospec format

• Carry out programs that require both imaging and spectroscopy. We could explore additional options opened by queue observing.

Binospec Initial Grating Choices

Grating Dispersion Resolution 1″ slit

Spectral Coverage

270 gpm 1.17 Å/pixel ~1300 ~5400Å

600 gpm 0.54 Å/pixel ~3000 ~2500 Å

Binospec Imaging

FOV ~15′ by 16′, use pair of 7 by 10 inch filters

Binospec Optics

2.9 meters

MMT f/5 focus

Binospec Layout

Binospec Layout

Binospec Image Quality

Athermalized Optics

Coupling fluid lenses

Binospec Lens Mounts

Nub Flexure

Nub

Flexure

Flexure mounts instead of elastomeric mounts: materialscompatible with coupling fluid and greater control of axial stiffness

Binospec Collimator Lens Cell

Lens 1

Lens 2

Lens 3

Lens 4

Lens 5

Lens 6

Lens 7

Lens 8

Fold mirror Lens 9

Teflon seals

Nub

O-ring

Flexure Epoxyinjection hole

Nubanti-rotation

pin

Seal interface rings Bezel

Binospec CCDs

Current deep depletion E2V CCDs

Active Flexure Control

512 x 2028 Flexure control CCD

Flexure control CCDswill monitor positionof fiducial fibers mountedon slit mask assembly.

Active Flexure Control in Operation

• Grating tilt for wavelength setting will be controlled by the flexure control system

• Flexure and focus shifts will be removed by 3-axis piezo stage in the dewar

• Flexure control system will have selectable lamps and a filter wheel to pass only the desired light for flexure control

Binospec on its handling cart

Cover/thermal shroud

Electronics boxes

CCDelectronics

Entrance window

Filter access

Changing Slit Masks, Filters and Gratings

Grating access

Slit mask access

Changing Filters and Gratings

Binospec Bottom View

Grating

Camera optics

LN2 dewar

Grating exchange

Collimator optics

Binospec Inverted

Binospec Top View – cover removed

Binospec Focal Plane Area

Slit mask cassette

Center field acquisitionand slit guiderOff-axis WFS

Binospec Status

• Mechanical design nearing completion: CDR fall 2006. Electronics design is mature.

• 10/12 CaF2 lenses coated and delivered

• 6/6 aspheric lenses nearly complete

• Major assembly task of mounting lenses in bezels will be prototyped this summer.

• Delivery late 2008/early 2009