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WNEW A 2.4 Meter TMA Survey Telescope Concept. Rodger Thompson University of Arizona Steward Observatory. WNEW CHARACTERISTICS. 2.4 meter 3 mirror anastigmat telescope utilizing the NRO telescope components.
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WNEW A 2.4 Meter TMA Survey Telescope Concept Rodger Thompson University of Arizona Steward Observatory
WNEW CHARACTERISTICS • 2.4 meter 3 mirror anastigmat telescope utilizing the NRO telescope components. • Dichroic splitting of the optical paths to produce 4 fields of view, each of which images 0.25 sq. degrees. • WNEW contains 8 filters in two sets of four that can be viewed simultaneously. • The plate scale is 0.11” per pixel. • WNEW also contains 8 grisms for low resolution spectroscopy
WNEW ADVANTAGES • Four fold dichroic multiplexing optimizes the very large field of view to maximize the scientific return. • WNEW is based on a previously funded Origins Probe study, the Galaxy Evolution Probe, with a very well studied and mature design. • WNEW achieves all of the WFIRST DRM science in approximately 1/3 of the time in twice as many filters. • The WNEW capabilities enable science significantly beyond the scope of WFIRST.
Use of the NRO Telescope as part of a Three Mirror Anastigmat System NRO Provided Component
Four Focal Plane Optical Schematic • Each array of detectors has two filters and two grisms to provide 8 photometric bands. • Each dichroic assembly has two dichroics. Dichroic Wheel Filter Wheel
Two Exposures Produce Eight Images POSITION 1, 4 IMAGES POSITION 2, 4 IMAGES
IMPLEMENTING WFIRST SCIENCE WITH WNEW • WNEW can implement all of the WFIRST DRM2 programs in less time with twice as many photometric bands. • The 8 WNEW photometric bands greatly enhances the scientific productivity of the WFIRST DRM2 programs. • The reduced time to implement the DRM2 programs provides extra time for innovative programs not envisioned for WFIRST.
WFIRST Survey Programs • Survey of 3400 sq. degrees to ABmag=26 • WFIRST: 429 days for 4 filters • WNEW: 122 days for 8 filters • Survey of 3400 sq.deg R=600 ABmag=22.5 per pixel • WFIRST: 284 days • WNEW: 61 days • Survey of Gal. Plane 1240 sq. deg. ABmag =25.1 • WFIRST: 160 days for 4 filters • WNEW: 15 days for 8 filters
EXO-PLANET MICROLENSING • Monitor >2 sq. degrees for J=20.5 star with S/N=100 for 250 total days. • Cadence < 15 Minutes • Time for WNEW to reach S/N=100 for J=20.5 in 4 filters is 224 seconds = 3.75 minutes. • Better than 0.4” resolution • WNEW has 0.11” pixels • Automatic color information in at least 4 bands • Automatic guard against chromatic false positives
WNEW AS WFIRST • WNEW easily meets all of the WFIRST DRM requirements in far less time than WFIRST. • WNEW easily meets all of the WFIRST DRM requirements in twice as many filters than WFIRST • WNEW can exceed all of the WFIRST DRM requirements and still have time for additional science goals.
AN ADDITIONAL SCIENCE EXAMPLE • Very deep imaging in 4 fields of 1 square degree for 1 year. • Fields separated by ~90 degrees on sky • 4000 second integrations • 8 integrations to cover 1 sq. degree in all filters • 223 integrations at each position in one year with 10% overhead
4 Sq. Degree 5s AB mag per Pixel 8 Bands provide excellent photometric redshifts for high z objects 4 Square degrees and separation greatly reduces errors due to large scale structure. High spatial resolution avoids confusion limit.
Technical Readiness • The WNEW concept was developed during two funded studies as an origins probe. As such it has a very mature design. • WNEW simplifies the original concept by retaining only infrared bands and restricting the focal plane to a single detector type. • Many components already have preliminary or in some cases a mature design.
Dichroic Design in Place 47 layer dielectric multilayer results in reasonable VIS/NIR wavelength separation at 35 degree incidence angle
Need to adapt previous telescope design to NEW components NEW Telescope Redesigned optics
Detectors • Four focal planes utilizing 16 H4RG detectors (4kx4k) each. Science 4x4 array Guiding arrays on one focal plane only
Spacecraft Based on GEP Design In drift away or L2 orbit the mirrors instrument and detector systems are radiatively cooled with no cryogenics required. Data transmission requires only 5 hours of DSN reception per day on a moderate size receiver equivalent to the Univ. of AZ 12m dish on Kitt Peak.
CONCLUSION • WNEW provides a greatly enhanced platform for carrying out the proposed WFIRST science program at higher sensitivity, in less time and with twice as many photometric bands. • WNEW provides new science capabilities to go beyond the proposed WFIRST program. • WNEW could start tomorrow.