Key Inputs / Requirements Version 0.5 TLH 16-Mar-05

Science Galaxy Formation and Evolution ISM, Disks, Star and Planet Forming Regions CMB and the SZE Solar System Studies KBOs and Irregular Satellites Write-ups are progressing The unique science of CCAT will be enabled by Combination of wavelength coverage, sensitivity, field-of-view Sensitivity is influenced by confusion (aperture size is very important)

Top Level: Requirements Item Req’ment Goal Notes Aperture 25 m > 25 m Sensitivity/Confusion Wavelength range 350 - 850 mm 200 – 1100 Field of view 10’ 20’ Surveys Pointing spectrographs cameras 0.35” 5” 2” 0.2” 3” 1” @ 350 & 200 mm blind pointing reconstructed Tracking one hour 20 min 10 sec 1” 0.25” 0.17” 0.5” 0.15” 0.1” Spec-Photo req’mt Elevation limits 30 - 80 15 - 85 From horizon Azimuth Range 270 0 is north What is reasonable time to move, repeak and move back on a source? Dead time at zenith ~ 2*10deg*60arcmin/deg*4sec/arcmin = 4800 seconds

Top Level: Requirements Item Req’ment Goal Notes Infrared mode (l < 40 mm, non-redundant masking) < 5 mm rms TBD panels < 5 mm rms 90% of panels Circumstellar disks Polarization capability (should be vs. l) calibratible to 0.2% calibratible to < 0.05 % Star forming regions, still TBD What is reasonable time to move, repeak and move back on a source?

Ancillary: Requirements Item Req’ment Goal Notes Instrument location Nasmyth Ltd. bent Cass Access, size, loading Delivered instrument f# f/8 f/6 Window/mirror sizes Focus dist. (from flange) 1 m (TBD) --- Nominal Focus range 0.5 m (TBD) 1.0 m (TBD) From nominal Chopping 2’ @ 0-0.5 Hz 5’ @ 0-1 Hz With M2 and/or M3? Scanning requirements 0.2 (/s) 0.14 (/s2) TBD ('') (/s) TBD (/s2) TBD ('') Rate (all directions) acceleration reconstructed pointing Based on “first-look” at instruments. Need further work on instrument concepts. Tech Memo on Chopping & scanning requirements being written by Dowell, Gowala, et. al.

Ancillary: Requirements Item Req’ment Goal Notes Instrument mass < 2 tons ? per instrument Instrument volume TBD Instrument power < TBD kW Online instruments 2 (TBD) 4 – 6 (TBD) Programmatic, weather Secondary blockage < 4% < 2% Daytime ops limited 24 hours There should be a few “typical” instruments which define the envelope of power, mass, and volume. Do we really need to have the “max” available for all online instruments?

Sensitivity Estimates: Status The atmosphere Data, models, & statistics in-hand & synthesized Continuum detection of point sources Herter, Stacey, Dowell, Bradford (basically agree) Confusion limits provided by Blain Low-Resolution spectroscopy Need to check yet Heterodyne Need inputs on this

Atmospheric Transmission 1000 450 350 200 Pardo models for 5000m (Radford). Optimized bands shown.

Water Vapor Stats From Blundell et. al (2002) tau(1.35 THz) statistics

Sensitivity vs. PWV 1-sigma in 1-second. Assume 30 deg from zenith, loss of 1.414 for differencing, 12 mm rms surface

Performance vs. Surface rms

CCAT Instrumentation Bolometer Array Cameras – more than 10,000 pixels 350 and 450 m at first light 620 and 850 m, likely in same dewar – filter wheel? 200 m likely 3rd band Direct Detection Spectrometers R =1000, 16 x 128 short slit grating spectrometer Spatial multiplexing Resolving power well matched to extragalactic science R = 100-1000, Z-Spec like wave-mode coupled spectrometer Coherent spectrometers for high spectral resolution science: e.g. Galactic star formation studies Spatial multiplexing important for extended sources Focus on shorter submm science, where we have a more distinct niche