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TMT.SEN.DRD.05.001.CCR26Page 8 of 60OBSERVATORY REQUIREMENTS DOCUMENTCCR 15August 13,2007 Updates as per ORD CCR15 change historyas documented inTMT.SEN.TEC.07.025.DRF12, including: Addition of REQ-1-ORD-2740 Change to REQ-1-ORD-2755 Addition of REQ-1-ORD-2756 Addition of REQ-1-ORD-2757 Change to REQ-1-ORD-2760 Addition of REQ-1-ORD-2761 Addition of REQ-1-ORD-2762 Addition of REQ-1-ORD-2785 Change to REQ-1-ORD-3505 Change to REQ-1-ORD-3655 Updates as per proposed errata andupdates as documented inTMT.SEN.TEC.07.025.DRF05, including: Change to [REQ-1-ORD-4310] Change to [REQ-1-ORD-4385] Consolidated acquisition requirements into asingle section. Merged previous softwarerequirements with pointing requirements.Reorganized and renumbered LightCollection Geometry SectionAdded a telescope optical throughputsectionAdded REQ-1-ORD-2670Added an Operational Efficiency sectionMoved software requirements section to theend of chapter 3.3.3.63.3.73.3.18.1CCR 14May 25, 20073.3.19.33.3.19.4DRF 13May 12, 2007DRF 12May 7, 2007DRF11May 1, 2007DRF10March, 20071.73.2.23.3.3 3.3.11 3.3.53.5.23.8 1.53.3.33.3.123.3.19.33.3.19.53.4.4.1 NumerouschangesNOVEMBER 27, 2013Updated ReferencesUpdated pupil obscuration requirementUpdated thermal background requirementUpdated IRMOS requirementsUpdated [REQ-1-ORD-4570]Updated [REQ-1-ORD-5505]ththUpdate after April 24 and 25 reviewComplete reorganization and rewriteABBREVIATIONSThe abbreviations used in this document are listed in the project acronym list [AD3]

TMT.SEN.DRD.05.001.CCR26OBSERVATORY REQUIREMENTS DOCUMENT2.OVERALL DESCRIPTION2.1PERSPECTIVEPage 9 of 60NOVEMBER 27, 2013The observatory collects the light of celestial objects, and extracts information about thecharacteristics of those objects from the collected light. The primary extracted informationis the spatial (angular) and spectral intensity distribution of the light of celestial objects ina defined field of view.The observatory as a system with its basic interactions to its environment is shown inFigure 1.Figure 1 The observatory system with its inputs and outputs2.1.1 System InputsThe primary input to the system is the light from celestial objects under investigation (i.e.science targets) after it has passed through the atmosphere of the Earth. This light issometimes known as the science beam (or beams if multiple sub-field-of-views areobserved simultaneously). When passing through the atmosphere, the wavefront of theoriginal science beam is distorted by time-variable refractive index changes caused byturbulence at various elevations above the surface of the Earth.The secondary input to the system is the light from celestial sources located near thescience beam on the celestial sphere. These sources are called natural guide stars(NGS) and are used for two purposes: (i) to measure telescope tracking errors andmisalignments, as well as (ii) to measure atmospheric wavefront distortion so that theeffect of these distortions can be removed from the science beam.Since suitable NGS may not be present near all desired science targets, the observatorywill generate artificial guide stars to measure atmospheric turbulence.The input light interface is above the observatory, where the air flow disturbance andthermal effects of the observatory buildings become negligible.The tertiary input to the system is a science observation request. This observationrequest defines what science target(s) to observe, what guide stars to use, how toconfigure the system for that observation, and how long to collect photons from thescience target(s). In classical observing, such a request may be developed in near-realtime by an on-site PI assigned a specific time window by fiat or by a time allocation

TMT.SEN.DRD.05.001.CCR26OBSERVATORY REQUIREMENTS DOCUMENTPage 10 of 60NOVEMBER 27, 2013committee. When queue (dynamic) scheduling is used, such requests are generated inadvance and executed in order of scientific priority when the system configuration,weather, and atmospheric conditions are suitable.Various auxiliary inputs are required for setting operating conditions and evaluate datacollected, including universal time, local weather and atmospheric (seeing) conditionsand system readiness. For safety reasons, information about work on or near thetelescope is needed as well as information about the presence of aircraft in theobservatory air space.2.1.2 System OutputsThe primary output of the system will be the science data stream; that is, the digitallyencoded spatial and spectral information collected by the focal-plane instruments. Thesescience data will be tightly bound to system status information recorded during thescience observation, such as time of observation, telescope pointing, AO systemconfiguration and status, focal-plane instrument configuration and status.The secondary output of the system will be the calibration data stream necessary toremove the signatures of the science instruments and the atmosphere from the sciencedata stream. These data will be based on observations of on-board calibration sources orastronomical objects. These data will be tightly bound to system status information asdescribed for the science data stream.The tertiary output of the system will be engineering data for performancecharacterization and optimization.2.2SYSTEM FUNCTIONSThe basic functions of the observatory are:a. Observation preparation. The system will provide user interfaces to allow thesubmission of observation and/or configuration change requests to the system.b. Light collection. The system collects the light of celestial objects, as sciencetargets, natural guide stars (NGS), and reference stars for calibration andacquisition, and focus this light into images of the objects. The system will be able tosense its own status and estimate self induced wavefront distortions in the sciencebeams, in order to reduce these aberrations by properly aligning and shaping theoptical surfacesc.Light processing. The system will process the light collected in order to deliverspecific spatial and/or spectral intensity distributions to the science detector. Thesystem will also be able to estimate and modify the wavefront of the science beamwith adaptive optics to reduce the effects of the atmospheric turbulence and residualsystem misalignments. In order to make these estimates, status of the atmospherearound the science beams will be probed with natural and laser guide stars (NGSand LGS).d. Data generation. The system will digitally encode and record image (undispersed)or spectral (dispersed) light intensity distributions delivered to the surface of thescience detectors. When such data result from observations of science targets, theywill be known as science data. When such data result from the observations ofcelestial calibration targets or terrestrial (built-in) calibration sources, they shall beknown as calibration data. Both kinds of data will be time-stamped and linked toinformation about system configuration and status as well as environmentalconditions during data acquisition. These meta-data will be complete enough to

TMT.SEN.DRD.05.001.CCR26OBSERVATORY REQUIREMENTS DOCUMENTPage 11 of 60NOVEMBER 27, 2013allow users to link science and calibration data for the purposes of removing theartificial signatures caused by the terrestrial atmosphere and the instrument.e. Data storage. All science and data (as well as all environmental conditions andengineering telemetry) generated by the system will be captured and stored.Storage duration requirements are specified elsewhere in this document.f.Data processing. It will be possible extract information from the generated data fordata quality control purposes. It will also be possible to remove artificial signaturescaused by the terrestrial atmosphere and the instrument from science data.In order to perform its basic functions, the system needs to provide operationalinfrastructure, including utilities, operational environment, and boarding/lodgingThe methods of light collection, processing and data generation are classified asoperating modes and system configurationsSystem configurations are realized by specific combinations of adaptive optics andinstruments. The different system configurations are identified by their characteristicscience measurement:a. IRIS, i.e. the Infra-Red Imaging Spectrometer, including the appropriateconfiguration of the Laser Guide Star Multi Conjugate AO System (MCAO);b. IRMS, i.e. the Infra-Red Multi-Object Spectrometer, including the appropriateconfiguration of the Laser Guide Star Multi Conjugate AO System (MCAO);c.WFOS, i.e. the seeing limited Wide Field Optical Imaging Spectrometerd. NIRES, i.e. the Near Infra-Red Echelle Spectrometer, including the appropriateconfiguration of the Multi Conjugate AO System (MCAO);e. IRMOS, i.e. the Near Infra-Red Multi-Object Spectrometer, including a Laser GuideStar multi-object AO System (MOAO);f.MIRES, i.e. the Mid Infra-Red Echelle Spectrometer, including a small field, lowemissivity, Laser Guide Star mid-IR AO system (MIRAO);g. HROS, i.e. the seeing limited High Resolution Optical Spectrometer;h. PFI, i.e. the Planet Formation Instrument, including an extreme AO system (ExAO)and coronagraph enabling very high contrast imaging.i.WIRC, i.e. the Wide Field Infrared Camera, including the appropriate configurationof the Multi Conjugate AO System (MCAO);Several operating modes are defined for the observatory, and there are specificrequirements related to each of these. The defined operating modes are:a. In Seeing Limited Operating Mode the telescope delivers light directly to theinstrument, without introducing further optical elements beyond the telescopemirrors. Wavefront correction is limited to closed loop active optics.b. In Adaptive Optics Operating Mode.the telescope delivers the light of the scienceobject to the instrument with aberrations significantly reduced by means of adaptiveoptics compensation of atmospheric turbulence effects and residual telescopeaberrations. The entire TMT observatory system is designed with adaptive opticscapabilities to improve science potential over a broad range of wavelengths andfields of view. The AO performance requirements are qualitatively very different foreach class of TMT configuration, and different AO system concepts are mostsuitable for each case:

TMT.SEN.DRD.05.001.CCR26OBSERVATORY REQUIREMENTS DOCUMENTPage 12 of 60NOVEMBER 27, 2013-The needs of near infra-red spectroscopy and imaging instruments (IRISand IRMS) are well met by a multi-conjugate AO (MCAO) system thatutilizes multiple laser guide stars (LGSs) and deformable mirrors (DMs) tomeasure and correct atmospheric turbulence in three dimensions, therebyproviding diffraction-limited image quality over a field-of-view significantlylarger than the conventional isoplanatic angle.-The degree of atmospheric turbulence compensation required forobservations in the mid-IR is comparatively modest, but system emissivitymust be limited by minimizing

TMT.SEN.TEC.07.038.REL06 CCR21 March 26 2009 Updates as per Level 1 DRD Change History Document, TMT.SEN.TEC.07.038.REL05 CCR20 January 28 2009 Updates as per Level 1 DRD Change History Document, TMT.SEN.TEC.07.038.REL04 CCR19 September 5, 2008 Updates as per Level 1 DRD Change History Document, TMT.SEN.TEC.07.038.REL03