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Binospec and future MMT optical spectroscopy
BK7 Entrance Window
Insulated Cover
Handling Cart
Daniel Fabricant
Wednesday, May 19, 2010
Binospec Design Goal
Build the most powerful spectrograph for deep optical surveys on an 8 meter class telescope
Power calculated by
P = Telescope Area · Throughput · FOV
Wednesday, May 19, 2010
Binospec in a Nutshell
• 3900-10000 Å wavelength range for imaging (g r i z) and spectroscopy
• 0.24″ pixel sampling• 200 mm collimated beam diameter – all refractive optics• Two identical beams observing adjacent 8′ by 15′ fields
• Continuous wavefront sensing maximizes image quality• Active flexure and focus control
Wednesday, May 19, 2010
Scientific Goals for Binospec
Three major themes have emerged:
(1)Near-Field Cosmology: Deep Studies of the Nearby Universe
(2) The High-Redshift Universe
(3) Transients and Transient Hosts
Wednesday, May 19, 2010
Binospec Operations
• Queue scheduling like the Hectos
• Full implementation of “piggy-back” projects to use all of the available slits and coordination of survey projects
Wednesday, May 19, 2010
Binospec Dual-Beam Optical Layout
Slit maskPeriscope fold mirrors
CollimatorCamera
Filter
Third Fold MirrorCCD
Grating
Wednesday, May 19, 2010
Binospec Spectroscopic ModesGrating Ruling
Order SpectralCoverage
(Å)
DispersionÅ/ pixel
Pixelsfor 1″slit
Resolutionfor 1″ slit
270 1 3900-9240 1.30 3.75 1340
600 1 4500-6960 0.60 3.47 2740
600 1 6000-8480 0.61 3.32 3590
600 1 7255-9750 0.61 3.20 4360
632 2 6405-7590 0.29 2.56 9427
Wednesday, May 19, 2010
Imaging Spectrographs and Fiber-Fed Spectrographs
• Imaging spectrographs (Binospec) preserve spatial information perpendicular to the dispersion
– Offer high fidelity sky subtraction– Small-scale kinematic information available– Operate as imagers– Offer the highest throughput
• Fiber-spectrographs (Hectospec) address the largest possible FOV
Wednesday, May 19, 2010
Binospec Offers Spatially Resolved Spectroscopy
Wednesday, May 19, 2010
Binospec’s Very Large FOV
15′ (150 mm)
8′ (80 mm)
1.33′ (13 mm)
1.26′ (13 mm)
1.68′ (17 mm)
Wave Front Sensor
X
Y
Guide strips
Wednesday, May 19, 2010
Binospec Aperture Mask
Up to 300 slitlets each 6″ long
Channel 1 Channel 2
15′
8′
Wednesday, May 19, 2010
Binospec’s Camera Optics
Lens 1
Lens2
Lens3
Lens4
Lens5
Lens6
Lens7
Lens8
Lens9
Binospec (2008)
Big optics allow:
Huge field of viewHigher resolution
Calcium fluoride lenses
Aspheric lens
360 mm
Wednesday, May 19, 2010
Binospec Offers Very High Throughput
Binospec
Hectospec
Telescope/Corrector optics included
Wednesday, May 19, 2010
Future of the MMT – before GMT
The 6.5 meter telescopes must provide our access to faint object spectroscopy
– Binospec will be the workhorse dark time instrument, combining spectroscopy and imaging to support observation of transients in the standard queue (fewer instrument changes)
– Binospec will be simpler to maintain than Hectospec, minimizing operations costs
Wednesday, May 19, 2010
Binospec Interior View
Filter Cassette
Optical Bench
Mounting Flange
Focal Plane Bench
Slit Exchange Cassette
A-frame Strut
Wednesday, May 19, 2010
Binospec Optical Bench
Dewar
CCD HousingGrating on Turntable
Grating Storage
Third Collimator Fold Mirror
Camera
Wednesday, May 19, 2010
Slit Mask Assembly
Wednesday, May 19, 2010
Grating Assembly
Wednesday, May 19, 2010
Oil-Coupled Doublet Prototype
Wednesday, May 19, 2010
Binospec Status
• Aiming for delivery early 2013 – contingent on funding
• Optics complete by end of 2010, high risk aspherics and CaF2 lenses already in hand. Major mechanisms and optical mounts prototyped and tested
• Main structure out for bid mid-June
• Major mechanisms completed: grating assembly, slit mask. Wavefront sensor under construction followed by single object guider. Main electronics assembly under construction
• Optical alignment equipment fully developed and tested on prototype optics, used for MMIRS
Wednesday, May 19, 2010
Binospec allows MMT scientists to lead in fields now dominated by DEIMOS/Keck
• Binospec gathers 65% of the light that DEIMOS collects per unit time
• Binospec has twice the slit length and three times the field of view of DEIMOS
• Power of Binospec = 1.3 to 2.0 Power of DEIMOS
Wednesday, May 19, 2010
The end
BK7 Entrance Window
Insulated Cover
Handling Cart
Wednesday, May 19, 2010
Wednesday, May 19, 2010
Binospec Exterior View
BK7 Entrance Window
Insulated Cover
Handling Cart
Wednesday, May 19, 2010
December 2007 Final Design Review
Chaired by Steve Shectman
“The design of the spectrograph in general impressed the committee to a very high degree”
Wednesday, May 19, 2010
Binospec uses all of the MMT’s available instrument volume and all of its weight carrying capacity to maximize throughput and FOV
3.26
156.80
Telescope Pivot
Wednesday, May 19, 2010
Large Calcium Fluoride Lenses
The closest approach to a perfect lens
Wednesday, May 19, 2010
Binospec Design Elements
• Large optics for large FOV, high resolution, wide spectral coverage
• Few glass-air surfaces with the best possible coatings• Very efficient detectors
• Robust mechanisms enhance reliability• Active flexure control for maximum data quality
Wednesday, May 19, 2010