- NASA Infrared Telescope Facility
Contents
1. 2010 For practical reasons it is required that the warm up time for the iSHELL instrument be less than 3 days Warm up is defined as the time required to get the instrument from its operational state to a temperature that the cryostat can be opened and worked on In this case all elements within the cryostat must be at a temperature greater than 0 Celsius As a goal the warm up time should be as short as possible without exceeding the warm up rates specified below 8 4 Warm Up Rates Estimate from J Rayner by analogy to SpeX Aug 2010 The major components optical bench optics and mechanisms within the instrument shall not be permitted to warm up at a rate greater than 0 1 K min The detector packages shall not be permitted to warm up at a rate greater than 1 0 K min The immersion gratings shall not be permitted to warm up at a rate greater than 0 1 K min TBD 8 5 Temperature Gradients During warm up cool down and during operation there shall exist no temperature gradients within any of the components that could result in significant stresses or damage to the components In determining what stresses are Page 24 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond allowable a safety factor of X shall be used for all metal components and a safety factor of Y will be used for all glass components 8 6 Alignment at Room Temperature Estimate from J Rayner by analogy to SpeX Aug 2010 Wherever poss2. Kelvin of this specified temperature 8 10 Immersion Grating Temperature Stability The Immersion Grating in iSHELL needs to be held at a temperature of 82 5 2 5 Kelvin and a closed loop control system is required to keep the Immersion Grating within 1 100 Kelvin of this specified temperature Page 25 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 9 Control System Requirements Specifications from E Warmbier Sep 2010 All iSHELL control systems shall meet the requirements listed below 9 1 General Control Strategy 9 1 1 Motor controllers shall interface with a PC shall accept commands from the PC and shall send back telemetry to the PC 9 1 2 Heater controllers shall be controllable from the controller unit itself or from a PC It shall also send back telemetry to the PC 9 1 3 Detector controller shall interface with a PC shall be controllable by the PC and shall send the detector data to the PC 9 2 Controller Types amp Physical Requirements 9 2 1 Motor controllers shall be off the shelf components 9 2 2 Heater controllers shall be off the shelf components 9 2 3 Heater controllers shall have front panel interfaces 9 2 4 All heater and motor controllers shall fit within the cool racks 9 2 5 Detector controller shall use the standard Stargrasp 2 board chassis and shall mount on the instrument 9 3 Control System Performance 9 3 1 The heater controllers shal
3. The total budget of the instrument is approximately 4M and it has been estimated to require about 14 man years of effort distributed over 4 years to reach completion 1 2 Document Purpose This document shall serve as a starting point for the technical staff for development of the iSHELL instrument Requirements stated in this document shall be clear concise and given in a way that the technical team will easily understand and will be able to carry on the design process with them All of the requirements in this document will be traceable to higher level requirements as given in sections 3 and 4 and should be derivable from them 1 3 Applicable and Reference Documents Science Case SC Science Requirements Document SRD DEN SGIR Controller Requirements Document MEER 1 4 Abbreviations Science Case Science Requirements Document Pp Pp Pp Page 6 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 2 Instrument Reference Design A general description of the instrument is given here as a basis for discussion This description can be considered as a pre conceived instrument concept or strawman design from which further refinements and or developments shall occur It is presented only to give the reader a general flavor of the instrument and the description given in this reference design should not be interpreted as any kind of established development or requirement of the instrument 2 1 Overview iSH
4. alignment 1 absolute photometry This is for an undersized stop An oversized stop is more tolerant to movement but transmits more background into the instrument When the instrument is mounted on the back of the telescope it must maintain its alignment to the following tolerances over the entire range of motion of the cassegrain instrument max change in elevation 90 degrees roughly factor of 2 more movement flexure than 2 hour observation sequence 1 0 mm translation in Z telescope optical axis 0 2 mm translation in X or Y perpendicular to the telescope optical axis 0 66 degrees rotation in Z axis of rotation of the cassegrain rotator 0 034 degrees rotation in X or Y tip or tilt on the mounting pad 7 3 Mass and Center of Gravity Requirements The total mass of the instrument shall not exceed BSUIRB and the center of gravity shall be located close enough to the mounting flange of MIM car so as not to apply a bending moment in excess of 4450 Nm in either X or Y tip or Page 21 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond tilt on the mounting pad when the telescope is slewed to its limits It is a requirement to meet the above stated limits yet it is a goal to have the mass and bending moments as small as possible 7 4 Volume Requirements The total volume of the instrument shall not exceed the envelope shown in the diagram below In addition to the hard limits shown in the diagram below consi
5. any of the elements not being immediately accessed Any mechanisms or components that are anticipated to require frequent maintenance will be made easily accessible through the vacuum jacket and radiation shield Page 23 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 8 Thermal Requirements The following is a list of thermal requirements that iSHELL shall meet 8 1 Cool Down Time Estimate from J Rayner by analogy to SpeX Aug 2010 For practical reasons it is required that the cool down time for the iSHELL instrument be less than 3 days That time will be measured and will commence with all components at room temperature and ending when all components are within 10 Kelvin of their final temperature with the exception of the detectors and Immersion Gratings which will be at their closed loop controlled temperatures As a goal the cool down time should be as short as possible without exceeding the cool down rates specified below 6 2 Cool Down Rates Estimate from J Rayner by analogy to SpeX Aug 2010 The major components optical bench optics and mechanisms within the instrument shall not be permitted to cool down at a rate greater than 0 1 K min The detector packages shall not be permitted to cool down at a rate greater than 1 0 K min The immersion gratings shall not be permitted to cool down at a rate greater than 0 1 K min TBD 8 3 Warm Up Time Estimate from J Rayner by analogy to SpeX Aug
6. eX PERPE NE PER evE UE 29 12 2 Helium Line IMIDPIGBS uico XO HD ncn eee EAS LEONEL E SPRLHEXE VERE RPL PEE CELER a Lad 29 12 3 Liquid Nitrogen ACCESS Porisi sse ate evt ER HASDEREVKR URN EF EINE EHE CRHRERAH RI UENREE ME GRUE 30 12 4 Electrical Interface COnRECHODBS uie ae testen tit rinse naa ani no le aa Pa nU V VO ERES A UP KK pA UK e alg 30 12 5 Power 717 77 7 MM T 30 12 6 Vacuum System CORN ECHO i cuscssvessscausvecicavenkiscsiendisvasssicstionniseersssacesseniesenvssccivs 30 13 Environmental Requirements sinsscscscssvcsssceascscvsssscacsiassnssecsssasassssvensieesnasseudssoctessvessseoesescenavene 31 13 1 Transportation Shipping ENnvirOnmMent sscccsssccsssscsscsscsccsscsscssssssssssecscsscsesseees 31 13 2 Facility Storage Operation Environment eee e ee eee ee eene entente tna nnn 31 13 3 Instrument Operation ENvir0nmMent scsesccseesrcsscsssssssccssccsscsscsscssssscssssessssseesseees 32 14 Other Additional Requirements cccsscccnsseensseennssesassseescnecaaiaasenndscaessaesnsesoaussesonsedecnanesensossenin 33 Page 4 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 14 1 Documentation Users Manual eee eee eee e eee eee eee eterne eene eee ee eet n neas eese e eee ena 33 14 2 Documentation Service Manual eee ee eee eee eee reete eee eee ette en neos eee e eee ten noe 33 14 3 Documentation As Built Drawings eee esee eee e
7. instrument TER oR A NT Ux 5 mounting bolt circle 115 5 ce Js ff i THRU LA K ES J J on d Ya redo EE E ui ER ii E E a SE p WA a S uum ur og peu COND hende Qe ur 3 FIGURE 10 i 9e bon bee Es S usce P 1 INSTRUMENT Lis ON ge i MOUNTING GC CMM MT c ir ELLEN IS EUN ee has OEE E N SURFACE o o UU 6 SCALE 1 4 PLOT DATE 10 19 1994 Figure X ISHELL The instrument shall be easily interchangeable with the other instruments on the back of the telescope As with the other instruments if an instrument change is required during the evening the time required for such a switch shall not exceed hour As a goal the instrument change time should be minimized 12 2 Helium Line Interfaces Page 29 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond The current instrument suite provides several sets of compressed helium lines As a goal iSHELL will utilize an identical set of lines and compressors for its cooling systems If this is not possible then the new cooling lines and compressors are to be designed and provided by the iSHELL project 12 3 Liquid Nitrogen Access Ports If the cooling scheme specified by the ISHELL instrument requires liquid nitrogen then the access ports for this shall be located such that the daycrew will be able to easily access them As a goal the cryogens will not spill out over the full range of motion of the instrument on the back of the telescope 12 4 E
8. instrument should be designed to minimize or eliminate such hazards during normal operation Page 33 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond Vacuum Hazards The instrument shall have protection from over pressure explosion hazard by internal leak of cryogens warm up of condensed gasses or operator error during warm up Cryogenic Hazards All staff required to handle cryogens will have had the appropriate training with respect to safe handling of cryogenic materials and oxygen deficient atmospheres The facility including both the telescope platform and laboratory areas should be provided with oxygen sensors for use when liquid cryogens are being handled Page 34 of 34
9. is reflected The TFP is re imaged onto the slit wheel by a collimator camera system A pupil image is formed following the collimator mirror and the system cold stop is placed here A k mirror image rotator is located immediately behind the cold stop Reflective slits in the slit wheel send the field surrounding the slit into the slit viewer Here a refractive collimator camera re images the slit field onto a Raytheon 512x512 InSb array A filter wheel in the slit viewer allows a selection of filters to be used for object acquisition guiding and scientific imaging A lens in the filter wheel is used to image the telescope pupil This pupil viewer PV provides a means to align the cryostat on the telescope The slit viewer will operate independently of the spectrograph The f 38 beam enters the spectrograph through the slit and order sorting filter wheel It is then folded and collimated at the first off axis parabola OAPI The silicon immersion grating IG is located at the pupil following OAPI An in out mirror close to the pupil is able to select either of two IGs IG1 covers 1 1 2 5 um and IG2 covers 2 8 5 3 um The IG is tilted slightly so that the emerging beam is reflected at OAPI to form a dispersed image of the slit at the spectrum mirror The beam reflected at the spectrum mirror is re collimated at OAP2 and forms a second white pupil image at the cross disperser XD mechanism Gratings in the XD wheel send the beam into the spectrogra
10. licensed version of the software required to edit those files will also be provided 14 4 Reliability iSHELL will be designed and built to have a downtime of less than M SPtotallsehedulediume on the telescope and where possible component failure shall result in gradual performance degradation 14 5 Expected Instrument Lifetime iSHELL shall be designed for an operational lifetime of 20 yrs Any major components that will need servicing or replacement during that time period must be identified and procedures for their replacement need to be detailed with a total downtime less than fdly including warm up and cool down times 14 6 Safety Requirements Cold and Hot Surfaces Any thermally active exposed parts subject to inadvertent contact by operating personal shall be labeled appropriately Surfaces lower than BS and higher than BS are considered thermally active Electrical Hazards Electrical hazards need to be labeled and interlocked appropriately The potential hazards always present with electrical and electronic instruments include batteries grounding isolation high voltage high currents and inadvertent or unexpected release of energy Mechanical Dangers Mechanical dangers need to be labeled and interlocked appropriately Potential hazards include sliding or rotating mechanisms that create a shearing or pinching point and exposed gears levers and rotating shafts capable of drawing loose pieces of clothing into themselves The
11. order to be interchangeable with the other instruments The instrument needs to be repeatably mounted and unmounted from the center section to the following tolerances 1 0 mm translation in Z telescope optical axis always operate instrument at the same focus within the ability to focus accurately 0 2 mm translation in X or Y perpendicular to the telescope optical axis cold stop alignment maintain absolute throughput within 296 between runs 0 66 degrees rotation in Z axis of rotation of the cassegrain rotator maintain absolute position angle within about 1 0 degrees rotation in X and Y tip or tilt on the mounting pad cold stop alignment maintain absolute throughput within 296 between runs 7 2 Rigidity on Telescope Derived from Zemax calculations by J Rayner Aug 2010 When the instrument is mounted on the back of the telescope it must maintain its alignment to the following tolerances over the course of an 2 hour max change in elevation 30 degrees observation sequence observations plus calibrations 0 5 mm translation in Z telescope optical axis depth of focus maintain throughput and focus 0 1 mm translation in X or Y perpendicular to the telescope optical axis cold stop alignment 1 absolute photometry 0 33 degrees rotation in Z axis of rotation of the cassegrain rotator for standard velocity precision 0 017 degrees rotation in X or Y tip or tilt on the mounting pad cold stop
12. ELL is being designed for a resolving power of R 70 000 and increased one shot wavelength coverage 54 2 10 um This is achieved through the use of a cross dispersed optical design and a 2048 x 2048 NIR array Because iSHELL is designed to maximize science return in the areas of planetary science star formation the interstellar medium and galactic astronomy the instrument is optimized for the H K and L bands The M band and part of the J band are also accessible Silicon immersion gratings are used to keep iSHELL manageably small about the same size as SPEX and affordable Absorption in silicon results in a short wavelength cut off in the J band at about 1 15 um Availability of large format arrays limits the long wavelength cut off is to about 5 um Slit lengths in the range 5 25 are needed for point sources and extended objects e g comets and planets 2 2 Basic Layout The iSHELL cryostat is mounted on the telescope at the cassegrain focus At this focus location the beam speed is approximately f 38 Inside the cryostat are three major optical sub assemblies the fore optics the slit viewer and the spectrograph In the fore optics the f 38 beam from the telescope enters the cryostat through the entrance window and comes to a focus at the telescope focal plane TFP A dichroic just inside the entrance window transmits the optical beam out of the cryostat through the exit window and into a wavefront sensor WFS and the infrared beam
13. MERSION GRATING 1 1 2 5 um IMMERSION GRATING OAPI OAP2 x SPECTRUM X DISPERSION MIRROR GRATING MECHANISM HH lt DROPA L7 H2RG DETECTOR FM3 Figure 2 iSHELL schematic layout The cryostat is of similar size to SPEX 1m3 and will nominally uses the same cooling scheme It contains an optical bench to which the optical sub assemblies are mounted The optics and bench are cooled to 75K using a liquid nitrogen can The radiation load on the cold structure is minimized by surrounding it with a radiation shield which is cooled using the first stage of a Cryodyne 1050 CP closed cycle cooler The spectrograph and slit viewer arrays are cooled to 38K and 30K respectively using the second stage of the cooler Cooling to operational temperature will take about three days components in the mechanism wheels take longest to cool 2 3 Detector Packages and Associated Electronics An in house STARGRASP infrared SGIR array controller runs the spectrograph and slit viewer array There are three subsystems the cryostat mounted electronics chassis a power supply and a computer connected via a local area network The cryostat mounted chassis has multiple slots that each houses an electronic board set Each board set consists of a PowerPC CPU and large FPGA 512 MB DRAM 16 10Mhz 16 bit ADCs and programmable bias and clock level generators These handle the generation of array bia
14. NASA IRTF UNIVERSITY OF HAWAII Document RQD 1 2 1 3 00 X Created on Jun 15 10 Last Modified on Sep 06 10 INSTRUMENT TOP LEVEL SPECIFICATION Original Author Tim Bond Latest Revision Tim Bond Approved by XX NASA Infrared Telescope Facility Institute for Astronomy University of Hawaii Revision History Revision No Author amp Approval amp Description Date Date Page 1 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond TMP inst spec ATTO6sep10 1 doc Page 2 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond Contents Minen P 6 LD Project iD OF OUT Re 6 E2 Document PHEBDSE God iioi hora Dr EH HAYA EE AS MEI o sooda daos POE PEE EDEN etie sauia 6 1 3 Applicable and Reference Documents eee e eere eee cette ee eere eese reset ne seen aseo 6 DA ADDY CVIAH ir c 6 2 Instrument Reference De simi C 7 PEU E 7 2 2 Basie P517 17 Tr 7 2 3 Detector Packages and Associated Electronics eeee eee eee eene eene enne 8 2 4 Observing Modes and Calibrationn cccccsocccccorssscsccsssccssccccssccccssccccssccessscccssscsessscceeees 9 23 Acguisition and UHNIIHE sq per hok P Eri eh beh cassona esocu EE GrP Pr Dr V Dr gR 9 3 Instrument Design Constraints Design Guidelines eee e eere creen eere ee
15. adence iSHELL SRD SR 12 The spectrograph shall be capable of taking and storing full array data at a sustained rate of up to 10 full data frames per minute standard read out with a goal of up to 30 frames per minute fast read out 4 13 Absolute Flux Calibrations iSHELL SRD SR 13 The instrument shall be capable of measuring absolute flux to an accuracy of 2 requirement 196 goal IA IA 4 14 Observing Efficiency iSHELL SRD SR 14 iSHELL shall have open shutter efficiencies total exposure time total elapsed time of 67 for 10 min observation gt gt 92 for a one hour observing block Overheads taken to include telescope slew acquisition guider setup and instrument configuration not more than 5 mins Page 16 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond Overheads do not include calibration flats arcs etc and observations of standard stars Page 17 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 5 Optical Requirements iSHELL shall meet the general optical requirements listed below 5 1 Existing Telescope Optics The optical design will assume the following with respect to the existing optics of the telescope IRTF Primary mirror Parabolic Concave Focal length 7642 225 mm 300 875 inches Conic Constant 1 IRTF Secondary mirror undersized to define pupil for IR applications Outer Diameter 243 84 mm 9 6 inches Inner Diameter reflectiv
16. alibration macros Some observations will only require relatively low precision and the calibration for these programs can be done at the end or beginning of the night or during the day This will require changing the instrument configuration to match the program Since mechanisms do not reposition precisely calibration is not as precise Radial velocity programs require very precise wavelength calibration and this is achieved by doing the wavelength calibration simultaneously with the observations with the use of a gas cell inserted into the beam immediately above the cryostat window Standard calibrations will also be required immediately following the observations with the gas cell still in place We are also considering the use of a laser comb for precise wavelength calibration of radial velocity observations but details are TBD 2 5 Acquisition and Guiding Target acquisition and guiding is executed with the infrared slit viewer Due to the high background at wavelengths longer than 2 5 um this is usually done in the J H K or similar wavelength narrow band filters Once the target is acquired it is placed in the slit by offsetting the telescope and guiding started Since guiding is implemented by offsetting the telescope guiding is necessarily slow and corrects telescope tracking at rates of 0 3 Hz In most cases guiding will be done on spill over from the target star in the slit Alternatively a guide star in the FOV of the slit viewer ca
17. aph camera lens The requirement is derived by convolving the profiles due to the slit Gaussian FWHM 3 0 pixels by design and the spot diagram EED a Gaussian distribution to a good approximation Page 18 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 5 4 Image Quality at the Slit Viewer Detector iSHELL SRD TR 10 The SV in series with the fore optics must not degrade the best image FWHM delivered by the telescope of about 0 4 a Gaussian to a good approximation by more than 10 In the SV this is met with 50 EED 27 um The origin of this requirement comes from the desire for iSHELL to not noticeably degrade the best images delivered by the telescope sensitivity and spatial information The requirement is derived by convolving the image profile at the slit Gaussian and the SV spot diagram EED Gaussian distribution 5 5 Cold Stop Alignment To achieve an absolute flux calibration of 1 the cold stop and telescope exit pupil need to remain co aligned to within 196 of their diameters both while observing the object and while performing the flux standard star observations Page 19 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 6 Detector Requirements iSHELL shall meet the general requirements listed below for both the spectrograph detector and the slit viewer detector 6 1 Mechanical Interface The detector shall be mounted such a way that once initially adjusted it can be remove
18. as a proving ground for this technology The silicon immersion grating has been produced and is being supplied by one of the Co PI s in Texas Dan Jaffe It is important to incorporate this technology to meet the original goals of the NSF proposal 3 5 Post Processing Software Design Guideline iSHELL SRD FR 3 A variety of software tools will be provided with the instrument that will help to make the instrument more effective and efficient This software suite will be developed and provided by the instrument team and additional tools may be provided at the request of observers based on the perceived advantage of such developments There are anticipated two different types of software tools one set for post observation data analysis and one set for use during the observations to expedite the observing process These tools will provide the following functionality Page 11 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond FUNCTION 1 FUNCTION 2 FUNCTION 3 Page 12 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 4 Summary of Top Level Science Requirements The following top level science requirements were identified from the proposed Science Cases Some rationalization has gone on with respect to these requirements As could be expected with any instrument it simply is not possible to have all of the desired functionally in a realistic instrument and as such some sacrifices have to be ma
19. d and reinstalled without necessitating optical realignment The detector shall be mounted such a way that it shall remain in a stress free state during cool down warm up or if exposed to any thermal gradients as specified in Sec 8 3 6 2 Thermal Interface The detector shall be mounted in such a way that it is thermally isolated and capable of being thermally controlled to the levels specified in Sec 8 6 6 3 Optical Interface The detector shall be mounted in such a way that it meets the optical alignment requirements over the all variations in temperature and geometric orientation flexure If this cannot be achieved with a fixed mounting scheme the detector shall be mounted on an appropriate stage and an appropriate control scheme will be utilized to provide the alignment required 6 4 Electrical Interface The detector shall be mounted with an appropriate connector to the controller hardware This connector will be easily accessed for installation removal of the detector and should not in any way be difficult risk damage to the detector Page 20 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 7 Mechanical Requirements iSHELL shall meet the general mechanical requirements listed below 7 1 Repeatability of Alignment on Telescope Derived from Zemax calculations by J Rayner Aug 2010 When the instrument is mounted on the back of the telescope it must be mounted on one of the existing MIM cars in
20. de It is the opinion of the team that the following requirements will provide for a very effective instrument at an extremely reasonable cost 4 1 Resolving Power iSHELL SRD SR 1 Spectral resolving power R 1 A2 at the center of the waveband shall be R 70000 required 80 000 goal Where is the wavelength AX is the smallest resolved wavelength interval using Rayleigh criterion 4 2 Sensitivity iSHELL SRD SR_2 iSHELL shall have point source sensitivities of for S N 100 in 3600 s at R 70 000 Vega magnitudes To achieve this sensitivity the average throughput shall be 1 2 0 05 required 2 _0 10 goal iSHELL SRD TR_1 In addition the read noise shall be 1 a lt _ 5e RMS with NDRs and read out overhead lt 30 0 s required b x 15 e RMS with NDRs and read out overhead lt 1 0 s c lt 100 e RMS with NDRs and read out overhead lt 0 1 s 2 a lt 2 e RMS with NDRs and read out overhead lt 30 0 s goal b x 7e RMS with NDRs and read out overhead lt 1 0 s c lt 50e RMS with NDRs and read out overhead lt 0 1 s iSHELL SRD TR 2 Page 13 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond In addition the dark current shall be 1 x 0 1 e s required 2 x 0 01 e s goal iSHELL SRD TR 3 In addition the instrument background shall be 1 x 0 01 e s pixel required iSHELL SRD TR 5 4 3 Wavelength Coverage
21. deration must be given to the access for all servicing operations as well as for all interfaces i e cabling helium lines In2 filling All iSHELL electronics shall be located in the cooled telescope electronics racks provided by the IRTF Exceptions to this are allowed only if absolutely necessary 1 e detector controller electronics Fig X Volume Restrictions 7 5 Vacuum System Requirements iSHELL shall provide a means to evacuate its cryostat while the instrument is on its handling cart possibly in the instrument prep area and while the instrument is mounted on the back of the telescope Vacuum ports on ISHELL will be accessible without removing the instrument from the telescope The instrument must be able to maintain a vacuum of at least XXX XX for a period of EX months without pumping 7 6 Mechanism Operational Requirements The individual mechanisms in iSHELL should be capable of moving to their desired positions within a time period of 0 5 min for simple mechanisms eg filter wheels and within 2 mins for precision mechanism e g grating and cross dispererser mechanisms If the mechanism requires a re initialization operation recalibration or to reconfirm Page 22 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond limits then the total time for this operation shall not exceed I min for simple mechanisms and 4 mins for precision mechanisms The total time for a re initialization operation fo
22. e button 48 8 mm 1 921 inches Primary Secondary Separation Distance vertex to vertex 7022 225 mm Primary Vertex to Instrument mounting face distance 1610 61mm Primary Vertex to telescope focal plane distance 2057 777 mm 5 2 Image Quality at the Spectrograph Slit iSHELL SRD TR_9 The fore optics must not degrade the best image FWHM delivered by the telescope of about 0 4 a Gaussian to a good approximation by more than 5 This is met with 50 EED lt 60 um At the telescope the best image quality is dominated by seeing best image FWHM about 0 4 220 um The requirement is derived by convolving the telescope image profile Gaussian and the spot diagram EED Gaussian distribution A degradation of 5 in the image quality at the slit reduces the spectrograph throughput by about 3 5 3 Image Quality at the Spectrograph Detector iSHELL SRD TR 8 The image quality at the spectrograph detector shall not degrade the slit limited spectra resolving power by more than 10 to maintain R gt 70 000 This requires 50 EED 18um This is specified in the dispersion direction x axis Lower image quality in the cross dispersion direction y axis does not affect spectral resolving power The slit limited resolving power is R 80 000 FWHM matched to a 3 pixel wide slit Refocusing of the spectrograph detector with wavelength is allowed The image quality in the spectrograph is dominated by the performance of the spectrogr
23. e eene eerte eene tn nettes eene setas nen 33 H44 RIOD Hr 33 14 5 Expected Instrument LifellB c eese eterna ree o XER IURI n EY EYAEE KERN MEHR ENASSRREE AERE R Ud 33 14 6 Safety ReghiFOeDIDIS a esie ede ao RAMS Vr CHE UHR SENE Ie E EU PERE YN ERI n ERA sepse ssri MEINE 33 Page 5 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 1 Introduction 1 1 Project Background iSHELL is to be a facility class infrared cross dispersed spectrograph developed for the IRTF using silicon immersion grating technology As a goal this instrument will provide a resolving power of up to 80 000 at 1 2 2 5 um and 70 000 at 3 5 um No other spectrograph in the Northern Hemisphere presently provides such a high resolving power at near infrared wavelengths Silicon immersion gratings are to be incorporated into the design to keep iSHELL manageably small about the same size as the IRTF facility instrument SPEX The immersion grating design will have the advantage of allowing high spectral resolving power without requiring an extremely narrow slit or large collimated beam diameters This will be the first facility instrument at 1 5 um to employ an immersion grating and therefore it will be an important demonstration of this new technology for future instrumentation The total instrument budget for iSHELL has been secured from several different sources NSF NASA UH and through the IRTF operations budget itself
24. iSHELL SRD SR 3 The instrument shall have the capability to position any wavelength in the range 1 2 5 2 um in the center of the array cross dispersion axis and the simultaneous wavelength range shall be continuous 4 4 One shot Simultaneous Wavelength Coverage iSHELL SRD SR 4 The simultaneous i e one shot wavelength coverage 82 is the continuous wavelength range covered in one setting of the instrument and shall be 9X 9X A 10 required A 5 goal IA IA Where A is the central wavelength setting of the instrument In order to achieve this the pixel field of view shall be 1 0 125 per pixel in dispersion direction required iSHELL SRD TR 4 Page 14 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 4 5 Slit Widths iSHELL SRD SR 5 The slit width matched to R 70 000 shall be 0 375 arcsec A selection of wider slits shall be available for better sensitivity in a range of seeing conditions and for improved sensitivity when higher resolving power is not needed 0 75 arcsec R 39 000 1 50 arcsec R 20 000 3 00 arcsec R 10 000 wide slit for absolute spectro photometry 4 6 Sampling iSHELL SRD SR 6 The smallest spectral resolution element R 70 000 shall be sampled by 3 0 pixels 4 7 Slit Lengths iSHELL SRD SR 7 A selection of slit lengths shall be provided 10 0 arcsec required 15 0 arcsec required 25 0 arcsec required 5 0 arcsec optimal 4 8 Signal to Noise Ratio Lim
25. ible the alignment of elements within the instrument will be such that their positions can be confirmed at room temperature and will achieve final alignment at the final cool down temperature 8 7 Thermal Repeatability Estimate from J Rayner by analogy to SpeX Aug 2010 It is not required for the optical elements optical bench or the mechanisms to be controlled to a specified temperature i e their temperatures are allowed to float within their allowed range It is required that the immersion gratings and detector packages be controlled to a specified temperature 8 8 Optical Bench Mechanism Temperature Stability Estimate from J Rayner by analogy to SpeX Aug 2010 The optical bench and all mechanisms in the iSHELL cryostat essentially everything within the radiation shield needs to be held at a temperature of 75 Kelvin and variations in temperature of 1 0 Kelvin of this specified temperature are allowable The exceptions to this are of course the detectors and Immersion Grating as mentioned above 8 9 Detector Temperature Stability The Detector in the iSHELL Slit Viewer needs to be held at a temperature of 30 1 Kelvin and a closed loop control system is required to keep the detector within 1 100 Kelvin of this specified temperature The Detector in the iSHELL Spectrograph need to be held at a temperature of 38 2 Kelvin and a closed loop control system is required to keep the detector within 1 100
26. its iSHELL SRD SR 8 Systematic noise effects shall not limit the measured S N to less than 1000 4 9 Velocity Precision iSHELL SRD SR_9 Without special calibration iSHELL shall enable the measurement of velocity of 1 km s required 0 4 km s goal lt lt The velocity measurement shall be stable over a period of hours 4 10 Radial Velocity Precision iSHELL SRD SR 10 With special calibration iSHELL shall enable the measurement of velocity of Page 15 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 20 m s required lt 10 m s optimal lt 5 m s goal The radial velocity measurement shall be stable over a period of months 4 11 Spectral Response Function SHELL SRD SR 11 To achieve a radial velocity precision about 10 m s RMS the skewness defined by the dimensionless third moment us must be known at all times to within 0 01 This requires a that provision shall be made to measure u to 0 01 arc lines or laser fringes b that us of the instantaneous optical SRF shall be stable between measurements e g daytime calibration to this precision or better c that u for the effective SRF being the combination of the optical SRF in b and any smearing brought about by image drift during the course of an observation shall be kept stable to within the same to 0 01 this requires the image motion across the face of the detector be 0 1 pixel during an observation 4 12 C
27. l control the temperature to 0 10 K of the set point minimum 9 3 2 The heater controllers shall have a set point command resolution of 0 10 K minimum 9 3 3 The heater controllers shall have a set point range of at least 25 K to 100 K 9 3 4 The motor driver control systems shall provide the required mechanical resolution for each mechanism NOTE The mechanism resolution is a function of the motor mechanical gearing and controller 9 3 5 The motor driver control system shall have the ability to move the mechanism at its required maximum rate NOTE The mechanical movement of the mechanism is a function of the motor mechanical gearing controller mechanism mass and power supply voltage 9 3 6 Feedback sensors shall be conditioned such that the controllers can meet control specifications 9 3 7 The detector controllers shall clock and sample the detectors at the rates and noise levels required to meet the science requirements Page 26 of 34 TMP inst spec ATT06sep10 1 doc Created by Tim Bond 10 Electrical and Electronic Requirements Specifications from E Warmbier Sep 2010 ISHELL shall meet the electrical and electronic requirements listed below 10 1 Grounding and Shielding Requirements 10 1 1 The electronics shall meet all requirements in the presence of internal or external electromagnetic interference Sensitive electronics shall be shielded as required 10 1 2 Grounding shal
28. l use a star topology Different system grounds shall remain as separate as possible and shall only tie together at one point 10 2 Electrostatic Discharge Requirements 10 2 1 When the instrument is not powered and is not mounted on the telescope the external detector connectors shall have shorting plugs in stalled NOTE The only ESD sensitive device in the instrument that requires special attention is the detector 10 2 2 Electronics excluding the detectors shall not require any special handling requirements beyond ESD wrist straps ESD bags and ESD bench mats 10 3 Power Requirements 10 3 1 All power for the electronics shall be supplied from power supplies residing in the cool racks 10 3 2 Detector power supplies shall be isolated from the motor and heater power supplies NOTE Power does not appear to be an issue There isn t a hard power budget The supplies used for the controllers _ supply much more power than required Attention must be given to the physical space required for the supplies and controllers since that isn t really known at the moment Page 27 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 11 Software Requirements Specifications from T Denault and based on previous facility instrument software Sep 2010 ISHELL shall meet the software requirements listed below 11 1 IRTF Software Requirements 11 1 1 Operating System Requirement The Operation Syste
29. lectrical Interface Connections TBD 12 5 Power Connections TBD 12 6 Vacuum System Connections The vacuum ports on iSHELL will be accessible without removing the instrument from the telescope The project will provide all of the hardware required for hookup to the existing vacuum pumps provided by the IRTF If it is determined that the existing equipment will not be adequate then a dedicated vacuum pump will be specified for the iSHELL instrument and the project will purchase and provide this pump as well as all of the hardware required for use of this pump Page 30 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 13 Environmental Requirements This section will define the operating environment for the instruments and its associated subsystems and how they must perform under these conditions Three separate environmental conditions are specified The first 1s involved with transportation the second with general site operations and the third with operating while mounted on the telescope 13 1 Transportation Shipping Environment The shipping environments are those conditions experienced when the instrument is being transported to or from the telescope The instrument and its components must remain undamaged after repeated cycles of these conditions It is not a requirement that the instrument meet this specification in an assembled operational condition A moderate level of work is acceptable at both ends of the shi
30. ms for computers should be CentOS CentOS is the standard OS at the IRTF thus integrating and supporting the systems with CentOS will require less time and effort 11 1 2 VNC Requirement The IRTF uses Virtual Network Computing VNC sessions to host instrument software A standard session display is 1280x1024 pixels The Graphical User Interface needs to be hosted in this VNC window Using multiple windows for an instrument is allowed 11 1 3 Integration with TCS3 and Autofocus systems is required 11 1 4 The spectrograph image viewer and mechanism control software should run independently from each other 11 2 Software SubSystems The following software subsystems are to be developed 11 2 1 IC XUI DV The Instrument Control IC application X Window User s Interface XUI and Data Viewer DV This suit of applications provides the high level control software and graphical interface to the instrument 11 2 2 Controller Software The embedded controller code in the SGIR hardware for controlling the IR Arrays H2RG and Aladdin 11 2 3 Mechanism Control Software Software that interfaces to temperature controllers motor controllers and other hardware IO controllers to provide control to the instrument s mechanisms 11 2 4 Data Analysis Software Data reduction software to assist the observer with image processing Page 28 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 12 E
31. n be used The centroid of extended objects can be guided on by increasing the size of the guide box The guiding scheme is very similar to that successfully used in SPEX see Figure 21 The only differences are the smaller FOV and pixel scale 30 x30 and 0 06 pixel respectively With further development it may also be possible to guide on features in extended objects in particular planets by using cross correlation techniques Since ISHELL works at high resolving powers its targets will be intrinsically brighter than those observed with SPEX making guiding easier Page 9 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 3 Instrument Design Constraints Design Guidelines iSHELL has several design constrains design guidelines imposed upon it These are not specifications or requirements as dictated by the science case for the instrument In fact they are simply guidelines or constraints that have come about largely by legacy type issues financial matters politically motivated forces available effort or possible use of existing infrastructures 3 1 iSHELL as a IRTF Facility Instrument Design Constraint iSHELL Science Requirements Document FR 1 ISHELL is to be used as a general facility instrument at the IRTF It shall be designed in such a way as to take advantage of the existing infrastructure at the IRTF and to be used in such a way as not to significantly increase the overhead required to maintain the IRTF instr
32. nd Center of Gravity Requirements ceres eere eee eee eene n netten netta eee tna nto 21 4d Folimg Regreniplisaqaesieednie otn in isa dd v nent EUR ERE Pr e sedens 22 45 Vacuum System ReguiFembetis us ieeeeiesexeie e ueke eo ka aene Aer INS EEEHN EE EEYRENEEPAQR VA E PEE NUR M RU 22 7 6 Mechanism Operational Requirements eee eee e eerte eerte nee enne netta ase ttnasena 22 7 4 dnstrument Bands aedis ted adv tH DVATDIUX RU IE EEUU LUE V OPE ELE UR DEXM VAI KN OH EVEN MUN 23 7 8 Servicing and Access RequiFembes eee aea sne trae eaa a re a eR Y Ree EUYA Neu ERU R PEN PNE EEY E EEUU p Vus 23 8 Thermal Regnmiemeltstaaoden ain aiino cO HO ird Fire da Ovi FE EE o EVER FEE E ER PYERE EIU E PAR CRI 24 MESE NE MT 24 8 2 COOL Down TALES c 24 6 3 PATI WIL NE Torr 24 6 4 Warm Up Rats c 24 8 5 Temperature Gradi ntSeisisssisssrsiisissssssrisessssrssosssssoesessos RARI isses snore rsss iess sisis 24 8 6 Alignment at Room Temperatur e sss ssssssssssssssoesssssssoessoosesosssoesssosssoessoosssosssosssoosssosee 25 5 7 Thermal Rep atabilit sssssesisssistsssssssvesssissrssssisrssisvossesevissssosssasovotssisore is ssesevso ovsis c s 25 8 8 Optical Bench Mechanism Temperature Stability cssccccoccsscsscsssscssscscsscsscsseseees 25 8 9 Detector Temperature SUID lity ecasssecviaresarsserrsscresesscersievesssssousssessessrenssseessoscousssenssoene
33. ne 10 3 1 iSHELL as a IRTF Facility Instrument Design Constraint e eere 10 3 2 Array Selection Design Constraint eee eere eene eene eee eee nee e eee en aee eta see ena see 10 3 3 Array Controller Electronics Design Constraint eee e eee e eee eere en nennt I 3 4 Immersion Gratings Design Constraint eee ecce eene eene eene eene eene seen netta seen Il 3 5 Post Processing Software Design Guideline eee Il 4 Summary of Top Level Science Requirements sscccsscsscsscssssccsssecsssesssssessscesssseseeees 13 4 1 CI Eus T p 13 DDS CISIIV ILD P ani sios 13 4 3 WAVCICN OL COVEN ACE ciii enr HEREIN INT IRE HRA ITI YS ULTRA UNE FETA isoo issos tssis Essos sasn VIE KE 14 4 4 One shot Simultaneous Wavelength Coverage ecce eee eee eee eene eene nennt 14 deo TE REB RENAE SE EEE E EEEE E E NA A E 15 BO SOLA EE PERPE 15 CREATURE Tro DH H n EStSt 15 4 8 Signal to Noise Ratio Limils ieeeieecivessnekesekaxe tis tk eia se eMe Ve o PERPE eR PUE FERRO EE PURA e PERO e eU EE 15 4 9 Velocity PRECISION e d ovde laine enamel ERE VEU RUE 15 LI Radial Velocity PFOCIIDR aui nie ri ter opa EneH nt quta pk Pug eaae e Pk xu Ou pe bi E VAY E PA ek VR VERE Fu RR IN 15 4 H Spectral Response PUNCH OM csisscssssscerssevarscasarssarssarscersiarsceveoesescisorsuesssersscesnoassorss
34. oeoe 16 4 12 CAMO CE TO siskot sss ti 16 4 13 Absolute Flux C ALDI AON ccssasesiesssaiccvessenescveusescessesscausosesseuvensessevisessereeseevdsveassecuss 16 4 14 ODS Ervine TD ICICN CY wnwssicevspriccrinris ied anima EE 16 5 Optical ttt les iiis CERTI 18 5 1 Existing Telescope m M 18 5 2 Image Quality at the Spectrograph Slit ecce eee eee eee cete eerte netten nee nnntn 18 5 3 Image Quality at the Spectrograph Detector eee eee eee eere eene eene netten etnue 18 5 4 Image Quality at the Slit Viewer Detector eee eee eee eerte eerte nene tn nenne 19 5 5 Cold Stop AISHIBORL oi onbres e HU MURRELUYKRHE LOYER PK rs bossi Kore FED YR DEVE TUE 19 Mistress MR ss sises 20 6 1 Mechanical Inter CC T 20 Uy E ip e Soosa oroS se SaS 20 Page 3 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 6 3 Optical INP UE T 20 6 4 Electrical Interfa CE eoi e pese e lier ba DX EPUE A FUROU HE CE ETUR A VU EXER DEEU CFI E resessie 20 7 Mechanical Re guiPemibnfs t sauce edpon deii ria nd cin ug eps ie bored e E Dav bale sienose sinoi sisisi 21 7 1 Repeatability of Alignment on Telescope e eee e eee eee eren eene eerte netten etant 21 7 2 Rigidity on Ielescop ssaeddeueninenie UP SUR DOR tasses PUDE Sbata nossos rons IVs REIR REEMEUR 21 7 3 Mass a
35. ovided by M Mumma at Goddard as part of the collaboration The array controller electronics to be used is an iteration of the STARGRASP detector controller utilized on the PANSTARRS science cameras The electronics was developed here at the IFA and identical electronics has been under development for upgrades to several of the other facility instruments SPEX and NSFCAM2 It is highly desirable to use a similar if not identical electronics suite for all of the facility instruments on the telescope Many of the array controller performance statistics are ITAR sensitive however a summary of the non sensitive characteristics are given below SPECTROGRAPH DETECTOR CONTROLLER Teledyne H2RG MODE Read Out Max Min Integration Typical Integration Max Cadence TBD Overhead s Time s Time s 3600 60 600 x 6 cycles 30 frames hr 60 5 10 6 co adds 10 frame min 5 03 10 co adds 30 fiames min SLIT VIEWER DETECTOR CONTROLLER Raytheon Aladdin II InSb MODE Read Out Max Min Integration Typical Integration Max Cadence Overhead s Time s Time s Sow 50 300 10 30 1 co add 10 1 1 2 co adds 30 frames min 1 lt 0 1 0 1 10 co adds 60 frames min Additional information ITAR sensitive may be found in attachment X 3 4 Immersion Gratings Design Constraint SHELL SRD FR 1 One of the main goals of the original NSF Proposal for funding was to develop a spectrograph utilizing a silicon immersion grating
36. ph camera lens which images the resulting spectrum onto a 2048x2048 H2RG array A calibration unit CU is located on top of the cryostat It contains illuminating optics an integrating sphere arc and flat field lamps and a gas cell An in out mirror above the entrance window is used to project calibration light into the instrument A gas cell is mounted on a two position stage between the entrance window and in out mirror so that it can be placed into the beam for radial velocity RV science observations An option for precision wavelength calibration required for RV science is to feed the output of a laser frequency comb into the integrating sphere Due to Page 7 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond its size 1m3 and stability required the laser comb is located in the instrument preparation room and its output fed to the integrating sphere via an optical fiber Figure 2 shows a general schematic layout of iSHELL FORE OPTICS FMI DICHROIC WINDOW GAS CELL i COVER IRTF TELESCOPE INTEGRATING W Window FLAT SPHERE A7N LASER L Lens LAMPS Nu COMB TFP Telescope Focal Plane COLL Collimator a s OAP Off Axis Parabloid CALIBRATION ARC UNIT CRYOSTAT i FM5 L3 L4 in L5 L6 LA COLD STOP 512x 512 SLIT WHEEL De d di InSb DETECTOR SLIT VIEWER ORDER SORTER SPECTROGRAPH WHEEL 2 8 5 3 um IM
37. pping process disassembly packing unpacking assembly inspection etc to ensure these conditions are met Ambient Temperature OMT TempraueShok HS Atmospheric Pressure IOL32S RBSNGLCIPRISENISVENONSIUUN Relative Humidity Lo o Vibration QUiSg Hzuptod0Hz o Sek 0 TN 13 2 Facility Storage Operation Environment The facility storage operations environment are those conditions experienced under normal facility operations including storage at the base and mountain facilities handling onto the MIM storage on the MIM operating on the MIM and disassembly from the MIM After repeated cycles of the above conditions the instrument must meet its operating performance requirements with no intervention from the operations staff other than routine tasks handling connecting services LN fill etc Ambient Temperature HSRONGHOSIE TempraueShok CMH Atmospheric Pressure IULS2SIRBEHGSAPE GENIEVENOSUUN Relative Humidity po Vieaion Oe Sek HEN Page 31 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 13 3 Instrument Operation Environment The instrument operating environment are those conditions experienced under normal telescope operations when the instrument is mounted on the telescope and in use All of the instruments performance requirements must be met under these conditions These conditions also include the testing of
38. r the entire instrument shall not exceed 4 mins Mechanisms should be configurable in parallel No mechanism shall move in the event of a loss of electrical power 7 7 Instrument Handling An appropriate handling scheme will be derived for handling the iSHELL instrument both in a laboratory environment and as well at the summit The handling scheme must accommodate the needs of the development team during integration and testing and will allow for full flexure testing at any orientation that the instrument may encounter while mounted on the telescope The handling scheme should spell out in detail the procedures required to move the instrument from the sea level integration and testing laboratories to the summit and also detail the procedures for mounting and unmounting from the back of the telescope Any hardware that is required for handling i e flexure rigs handling carts lifting eyes specialized crates needs to be identified designed and fabricated as part of the instrument design process 7 8 Servicing and Access Requirements Wherever possible iSHELL shall use standard unmodified commercially available components Access to internal components and subassemblies shall be considered in the iSHELL design Tools and hand clearances will be considered as well as space requirements for the removal of relevant components The servicing and maintenance that is to be performed on iSHELL should not impact the optical alignment of
39. ses and clocks and the amplification digitization and transport of pixel data to the computer called a pixelserver Control and data transport is Page 8 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond accomplished over a one gigabit fiber Ethernet interface The software running on the PowerPC CPU is open source C code The power supply is an Ethernet controllable multiple output system that supplies the necessary voltages to the controller chassis The LINUX computer is completely off the shelf with no additional plug in boards and there is no particular favored vendor 2 4 Observing Modes and Calibration iSHELL has three basic spectroscopy modes Short cross dispersed mode SXD covers observations done at 1 2 5 um Radial velocity RV mode is a subset of SXD mode in which observations are made through a gas cell Long cross dispersed mode LXD covers observations done at 2 8 5 3 um In addition the infrared slit viewer that is used for acquisition and guiding can also be used for scientific imaging Standard calibration requires obtaining flat field and arc lamp exposures Typically these will be acquired immediately following an object and standard star observing sequence This requires that the spectrograph configuration not be changed The only change will be to move the external in out mirror into the beam so that the spectrograph can view the calibration lamps The calibration sequences will be run under command of c
40. ss 25 8 10 Immersion Grating Temperature Stability eee eee eret eee eee ettet tnue 25 9 Control System R qgiiremelifazooascepnn d bn EH RETE ED EORR UAE EFEDU DELENDUM IR RUECO MEER EUR ER ORE REE 26 3I General Control Mrdleey uo ovs eene na arit FU cera AS rh EYE V e ERkH S PEDREN VATER AKK Vr P Da ua 26 9 2 Controller Types amp Physical Requirements eee eee crees eren eene netten netu 26 9 3 Control System PerfOF ml Q8 accuse eins Rode RR IA URN UH PRCREFEOHR PEEOPERE UE FERE UE UE RDUM COM REN REP dE ERA 26 10 Electrical and Electronic Requirements eeee eee e esee eene eren eee enne einst en netta se tna seo 27 10 1 Grounding and Shielding Requirements eee e ee seen eene eren netten 27 10 2 Electrostatic Discharge Requirements eee e eee e eee eee e eee n netten seen as enae 27 10 3 DM TI RETE 27 11 Software FG MUM CUTAN oci eri acess HUE EAE CER EURO RYE LFU ERE ERE CI ERE FI EHE PEEL E EUEHD ER CHAP HEAR AERA ERERE 28 11 1 IRTF Software REGU CMCHIS aene ese rv XE EMR SERE SN PEN EK VRYEFK FA TEUER VERE YR UR DRE d 28 11 2 Software Sub S y SEES e dei Win oa p pF RIVA OEVE Ep RADI C RA QU OU MD RUM s iso IVR MEN FORE 28 12 External Interface Requirements xsascsasecscasecascreansoosuecsanecieaccnssieaniesocuioanevsninanssiennsveouxssanasane 29 12 1 Mounting on MIM and Telescope ise nenas thin re raY en i rb nen Ye Ve Een a Ye bbY
41. the instrument on its handling cart either at the telescope or at the base facilities prior to acceptance and delivery Ambient Temperature D TempraueShok HHS Atmospheric Pressure E Relative Humidity lina fF Gravity Orientation Any orientation experienced while mounted on telescope Vibration Occasional wind blown dust sand and insects Page 32 of 34 TMP inst spec ATTO6sep10 1 doc Created by Tim Bond 14 Other Additional Requirements The following is a list of additional general requirements that iSHELL will meet 14 1 Documentation Users Manual The iSHELL instrument will provide the IRTF with a detailed user s manual During the development of the instrument an OCDD will be produced and maintained and at the end of the commissioning phase the OCDD document will serve as a basis for the final user s manual 14 2 Documentation Service Manual The iSHELL instrument will provide the IRTF with a detailed service manual During the development of the instrument an FPRD will be produced and maintained and at the end of the commissioning phase the FPRD document will serve as a basis for the final service manual 14 3 Documentation As Built Drawings A complete set of as built drawing both electronic and paper versions will be produced and prided to the staff of the IRTF for future reference and possible upgrades A server with all of the 3D part and assembly drawings will be provided and a
42. ument suite iSHELL will be mounted to the bottom of the telescope on the existing MIM structure and will be easily interchangeable with the other existing IRTF instruments iSHELL will be made available to the general IRTF community The instrument will fit within an envelope that can be accommodated on the existing MIM and the instrument will not exceed a mass that cannot be handled by the MIM and or Telescope The instrument shall utilize wherever possible existing services provided to back of the telescope and if additional services are required they will be included in the design The instrument will be designed to accept the existing F38 approx beam delivered by the telescope and the instrument shall be capable of existing and operating within the IRTF dome environment 3 2 Array Selection Design Constraint iSHELL SRD FR 2 There are two arrays used in iSHELL a 512x512 InSb array used in the slit viewer and a 2048x2048 H2RG array used in the spectrograph Properties of the two detectors are as follows F of Pixels Pixel Pitch of Pixels Pixel Pitch Additional information ITAR sensitive may be found in attachment X Page 10 of 34 TMP inst spec ATT06sep10 1 doc Created by Tim Bond 3 3 Array Controller Electronics Design Constraint Decision was made to use the Teledyne H2RG array for the spectrograph and to use a Raytheon Aladdin II InSb array for the slit viewer The former was purchased the latter was pr
43. xternal Interface Requirements iSHELL shall meet the interfacing requirements listed below 12 1 Mounting on MIM and Telescope The mounting and unmounting of the instrument shall use the existing infrastructure provided by the IRTF ie cassegrain area platform dome cranes forklifts If the infrastructure available at the IRTF is not able to provide the required functionality then any addition equipment required shall be designed and provided as part of the iSHELL project The mechanical mounting interface of the instrument shall conform to the existing interface on the MIM transport cars This interface is shown in figure X below Alternative interfaces may be investigated and utilized but these new alternative interfaces must not affect the use of the current suite of instruments and must still allow instrument changes to occur within the specified time limits Icoking up at the e e bis 5 p mounting plate o Menu o 4 Vous um uie qug qn BS mercedem uo oi et oe i oO p oe Ote A TX 1 i we c NS 1 small instrument 2 18 NNa gn Q J e ud E CY A AL A NE AS SHOWN EN lt d Ba Mi X i on 18 000 dm Hu FU I j NUR x i H o i amp i i b A a WA EN 1 A E i a d NNN Vi N x E WA m uu Pe af Uc ee ue X A Y p M PT C MN TEM Y 38 oF ng i NEU T a p ON POE l EN i HB 3 FAR SIDE ry Hu IE Re cR CE FT Eat g Pad es ii i a ES id large
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