1. Binospec - Next Generation Optical Spectrograph for the MMT
Daniel Fabricant, Robert Fata, Mark Mueller, Jack Barberis, Tom Gauron, and John Roll

2. Binospec at a Glance
Dual beams address adjacent 8′ by 15′ fields of view (30′ total slit length)
3900 to Å spectral coverage
Spectral resolution ~1300 – 5000 with 1″ wide slit
Sampling is 0.22″/pixel on 4K by 4K array

3. Binospec vs. the World Spectrograph Field of View (spectroscopy)
Maximum Spectral Resolution
Binospec-MMT
240 sq arcmin
~5000
DEIMOS-Keck
80 sq arcmin
VIMOS-VLT
224 sq arcmin
~2500
IMACS- Magellan
120 sq arcmin
>500 sq arcmin
>5000
<2500

4. 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~5.8
5.5 hrs with DEIMOS
9 i’ dropouts in 200 sq
arcmin GOODS-N field

5. 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.

6. Binospec Initial Grating Choices
Dispersion
Resolution 1″ slit
Spectral Coverage
270 gpm
1.17 Å/pixel
~1300
~5400Å
600 gpm
0.54 Å/pixel
~3000
~2500 Å

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

8. Binospec Optics
MMT f/5 focus
2.9 meters

9. Binospec Layout

10. Binospec Layout

11. Binospec Image Quality

12. Athermalized Optics
Coupling fluid lenses

13. Binospec Lens Mounts
Nub
Flexure
Nub Flexure
Flexure mounts instead of elastomeric mounts: materials
compatible with coupling fluid and greater control of axial stiffness

14. Binospec Collimator Lens Cell
Fold mirror
Lens 9
Teflon seals
Nub
O-ring
Flexure
Epoxy
injection hole
anti-rotation
pin
Seal interface rings
Bezel

15. Binospec CCDs
Current deep depletion E2V CCDs

16. Active Flexure Control
512 x 2028 Flexure control CCD
Flexure control CCDs
will monitor position
of fiducial fibers mounted
on slit mask assembly.

17. 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

18. Binospec on its handling cart
Entrance window
Electronics boxes
CCD
electronics
Cover/thermal shroud

19. Changing Slit Masks, Filters and Gratings
Filter access
Slit mask access
Grating access

20. Changing Filters and Gratings

21. Binospec Bottom View Grating exchange Grating Camera optics
Collimator optics
LN2 dewar

22. Binospec Inverted

23. Binospec Top View – cover removed

24. Binospec Focal Plane Area
Slit mask cassette
Center field acquisition
and slit guider
Off-axis WFS

25. Binospec Status
Mechanical design nearing completion: CDR fall 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