TELESCOPE

• High performance three mirror anastigmat
• 2-m diameter ULE honeycomb F/1.2 primary
• 144 mm x 144 mm corrected field (3 micron rms spots)
• Strehl ratio at 2 microns > 0.8 over field of view
• 150 nm rms wave front error
• Low background
• Earth shield completely baffles terrestrial thermal radiation
• Primary, secondary and subsequent optics < 180 K
• Throughput/emissivity  >0.9 / <0.1

SPACECRAFT & ORBIT

• Delta-2/GEOLITE TRW bus
• 105 minute, 900-km Sun synchronous/terminator orbit
• No terminator crossings
• Stable thermal environment
• Telescope to points in anti-sun direction
• Stable thermal environment & maximum power from solar panels
• Nominal pointing zone in ecliptic latitude: -5 < b < 5, available entire orbit
• Extended pointing zone available if telescope slews twice per orbit
• -5 < b < +25 (space craft N of equator)
• -25 < b < +5 (space craft S of equator)
• Restrictions minimize terrestrial heat load
• Telescope advances ~ 1 degree per day in ecliptic longitude
• Mission duration 3+ years
• Sky coverage rate in survey mode
• 2.5 sq degrees/day, 900 sq degree/yr
• 400 s total exposure time per field
• K = 25.3 AB, SNR = 10  point source sensitivity
• Two 200 s exposures separated by 4 hours
• 100 % redundancy corner-in-center tiling ensures astrometric and photometric integrity
• Revisit 50% of the fields every other year
• Proper motions with 1 and 2 year baselines
• Recover Kuiper belt objects
• Total sky covered after 3 year mission
• 1800 sq degree one or more epoch
• 900 sq degrees two or more epochs
• 450 sq degrees three or more epochs
• Pointed observations to K = 29.5 AB, SNR = 10 also available
• Ground station: SSL, Berkeley
• Science data rate
• 209 kbytes/s uncompressed at 16 bits/pixel (18 Gbytes/day)
• Science data pipeline at IPAC

INSTRUMENTATION

• Three x two mosaic of six 2k x 2k infrared arrays
• Sloan style camera
• Three 2 x 1 sub-mosaics, each with a single fixed filter for J (1.0-1.4), H(1.4-1.9 micron) & K(1.9-2.5 micron)
• 10' x 5'  instantaneous FOV per wavelength per band
• Nyquist sampled at 2.8 microns, 0.5 lambda/D = 0.15 arc sec/pixel
• Array properties
• Format: 2k x 2k
• 0.9-2.5 micron response HgCdTe
• Low noise detectors
• Dark current: < 0.03 e-/s/pixel
• Read noise: < 3 e- rms (multiple correlated sampling)

SCIENCE HIGHLIGHTS

• Discovery of the first quasars
• Sensitive to all quasars z < 12 within the survey
• Robust star and galaxy rejection
• J/H/K colors identify z > 5 quasars
• Diffraction limited performance at K eliminates galaxies