Data Set Overview:The Composite Infrared Spectrometer is a dual-interferometer carried on theCassini spacecraft Remote Sensing Palette. Cassini was launched on 15October 1997 and due to arrive at Saturn on 1 July 2004. En route toSaturn, Cassini made a gravity-assist maneuver at Jupiter in December2000, which allowed for a six-month Jupiter observing campaign. CIRS wasoperated in full science mode for much of this six month period,either as the 'prime' instrument controlling pointing, or as a'ride-along' when another team was 'prime'. The CIRS Jovian datasetforms the first part of the CIRS archive.The Cassini Prime Mission after SOI (Saturn Orbit Insertion) is thefirst four years of tour, from July 2004 to July 2008. After thattime, if approved and technically possible, an extended mission periodwill begin. During the first four years of Prime Mission, Cassini willundergo 76 orbits (revs) of Saturn, known as 0, A, B, C, 3 ... 74. Theoriginal orbits 1 and 2 were replaced with A, B and C when the missionwas redesigned in order to accommodate radio link issues with theHuygens probe, discovered after launch. The probe delivery to Titan isscheduled for rev C. There are 44 targeted (i.e. close) fly-bys ofTitan planned during the first 76 revs.See MISSION.CAT file for more information on the Cassini mission.Science Objectives and Observation Strategy-------------------------------------------The Cassini/Huygens mission tothe Saturnian system is designed to investigate the following targets:1. Saturn2. Rings3. Titan4. Other ('icy') satellites.The overall mission may also be broken in physical target types:1. Atmospheres (Saturn and Titan)2. Surfaces (Titan, and other satellites).3. Magnetosphere: fields, particles and solar wind interaction (Sun-Saturn)4. Orbital mechanics (rings, satellites - especially Hyperion).CIRS contributes to the investigation of many of these areas:SATURNSensing of tropospheric and stratospheric temperatures and composition.This includes abundances of the major and minor species, the hunt for newgaseous species, isotope ratios for major species, anddynamics. Allocating time for Saturn observations was theresponsibility of the Saturn TWT (Target Working Team), which was incharge of much of the periapse parts of each orbit (rev). There wasalso input from the Atmospheres Working Group (AWG) which dealt withhigh-level science recommendations.sCIRS Saturn atmospheric science goals are met with observations at avariety of inclinations, range from Saturn and, in some cases, inconjunction with other teams' observations. The standard CIRS requestsinclude:Name Range DetailsCOMPSIT >60Rs Composition sit and stare at 0.5 cm-1 spectral resolution using FP1. Uses all 3 focal planes. Search for oxygen compounds (CO2 and H2O) and new molecules.MIRMAP 25-40Rs Mid-IR maps, centered at a latitude, with the long axis of our arrays (Z) pointed toward the pole of Saturn to allow the planet's rotation to map out a latitude band. 3 cm-1 resolution.FIRMAP 15-25Rs Far-IR maps, constructed by slewing equatorward over a hemisphere. Slews overlap and repeat to map out the entire hemisphere. 15 cm-1 spectral resolution.FTRACK <10Rs Campaign with VIMS and ISS to track features across the disk from limb to limb, including limb sounding. FP1 nadir sounding at 3 cm-1, FP3/4 limb sounding at 15 cm-1. The goal is to study vertical structure and poleward heat transport.LIMBMAP <6Rs Vertical sounding at multiple latitudes on the limb at 15 cm-1.LIMBINT <6Rs Long integrations for vertical composition at one location on the limb. Resolution : 0.5 cm-1 or 1 cm-1 (TBD).NADIROCC<10Rs Helium abundance measurements taken by following the Radio Science Team's occultation points across the disk, 3 cm-1 res.OCCLIMB <6Rs Independent verification of vertical temperature profile at Radio Science's occultation latitudes.REGMAP <10 Rs Regional mapping and/or composition feature tracks, to fillCOMPFT/ in coverage not obtained by the other observations (0.5 or 3 cm-1)TEMPSIT Early temperature map. Res:3 cm-1. Sit on CML, FP3/4 N-S, let planet rotate to cover all longitudes. Arrays cover Southern Hemisphere (north blocked by rings).MIRCMPSIT Early composition sit and stare. Res : 0.5 cm-1. Sit on CML, FP3/4 N-S, Arrays cover Southern Hemisphere (north blocked by rings).FIRCMPSIT Early far-IR composition. Res : 0.5 cm-1. FP1 centered on South Pole and on mid-Southern latitudes.RINGSMeasurement of the infrared spectrum at varying phases, leading toconclusions about ring particle size, shape, composition, distributionand dynamics. Allocation of time for rings observing was carried outby the Rings TWT, in conjunction with the Rings Working Group (RWG).Ring observations are made as a function of ring opening angle, orspacecraft elevation:* Faint Ring Long Integrations. The low optical depths of thefaint D, E, F and G rings will pose particular observing challengesfor CIRS. These rings are best viewed edge-on because this geometryenhances the instrument fill factor. Low spectral resolution of 15cm-1 with FP1 provides the best signal-to-noise and should besufficient for detecting the variations of emissivity with wavelength,which is our primary measurement goal. From close range (~ 10 RS) andsmall opening angle, the FP1 filling factor will approach 1% whenpointed at the F rings ansa. Integrations of ~ 10 minutes should yieldusable signals. However, because the F ring is so clumpy, it needs tobe sampled at many longitudes before a truly representative spectrumcan be obtained. Observations will consist of alternating between bothring ansas every ~30 minutes to achieve the most complete rotationalcoverage of this ring. The E ring will be observed by pointing FP1near the orbit of Enceladus, where the long edge-on line of sightthrough the ring maximizes the fill factor. However, this fill factorwill still remain quite low, ~ 10-4, so , detecting the E ring willrequire many, perhaps 100 or more, hours of integration. On the otherhand, because the ring is so thick vertically, the observing range canbe quite large (3040 RS). More observing time is available then duringthese apoapse periods of the tour. The VIMS and UVIS instruments willalso require substantial integration on this ring, so E ringobservations will be cooperative activities between all of Cassini'soptical remote sensing instruments. Unfortunately, the best possiblefill factors for the remaining rings, D and G, are still lower thanfor Ring E. It is unlikely that either will be detected with CIRS.* Composition Integrations. CIRS will determine with uniqueaccuracy the ring spectrum between 50 and 1000 micron. As intimatelymixed contaminants significantly influence this part of the spectrum,mixtures derived from the visible and near-infrared spectra will betested against this new spectrum. Spectra of the three main rings overthe full CIRS wavelength range will be obtained to determine possibleradial variations in the bulk composition. Two types of observationswill be made: high spectral resolution (0.5 cm-1) FP3 emissionmeasurements of the A, B and C rings, and high spectral resolutiontransmission measurements of the rings with the rings against Saturn.The former can be obtained from large ranges 2040 Rs because of FP3sfine spatial resolution; long integrations of 1020 hours will beobtained on representative locations in each ring. The transmissionmeasurements will be made from 20 Rs at relatively low ring openingangles. This will allow a search for absorption features in the A andC rings, and the Cassini division. The same region of Saturn will beobserved in at a similar spatial resolution when the rings are notpresent, to establish the background. The transmission spectra willbe obtained over a series of emission angles.* Stellar Occultations. A handful of stellar occultations areobserved by CIRS to directly obtain the ring opacity in the infrared.Only a limited number targets are observable by CIRS, including CW Leoand Eta Carinae. Eta Carinae occultations are only observable duringthe final month of the tour. Occultations are observed in one FP3pixel (CW Leo) or one FP4 pixel (Eta Carinae) at 15 cm-1 spectralresolution.* Radial scans. These scans are typically executed between 5 and20 Rs over a range of spacecraft inclinations, from low (5 deg) tohighest possible inclination (75 deg), radial mapping (FP1, FP3) of therings, on both lit and unlit sides, over a range of spacecraftelevations, inclinations, local times and phase angles, is performedto obtain broadband radiometric measurements of the total flux in theCIRS wavelength range. Sets of observations are obtained in each ofthe inclined orbit intervals to map the temperature variation in therings with changing solar illumination. Two types of scans areplanned. So called temperature scans will consist of spectra at 15cm-1 spectral resolution of the lit and unlit sides of the rings atmany incidence and emission angles and provide prime information onthe ring thermal gradient as a function of radial distance toSaturn. Submillimeter scans will be made of spectra at 1 cm-1 spectralresolution of the lit and unlit sides of the rings to map the thermalcharacteristics and composition of the ring particles out to 1 mm.* Azimuthal scans. These observations are executed between 5 and20 Rs at spacecraft inclinations greater than 20 deg. They will be usedto study both the surface properties, the vertical dynamics and thespin of ring particles. Observations of the cooling and heating of thering particles entering and emerging from the planetary shadow areplanned to derive particle thermal inertias for all three mainrings. It will make measurements at moderate radial resolution(typically 1000 km) across the shadow boundaries at low spectralresolution (15 cm-1) with the FP1 field of view. To constrain thevertical dynamics of ring particles, the temperatures of the mainrings will be measured by CIRS along the ring azimuth of the mainrings, from the exit of the shadow (morning) to the evening ansa, bothon the unlit and unlit faces. This unique experiment will be realizedwith spectra at low spectral resolution (15 cm-1). Spins create bothan azimuthal asymmetry in the ring temperature and a dependence of thetemperature with the emission angle, due to day/nightcontrast. Circumferential scans at a variety of phase and emissionangles will be executed to detect azimuthal asymmetries and theanisotropy in the ring particle emission function which are bothfunction of particles spin and thermal inertia. Occasionally, whenobserving time is highly disputed, long azimuthal scans (8-to-20 hourslong depending on geometry and face) will be replaced by a series ofradial scans at different azimuths.TITANSensing of tropospheric and stratospheric temperatures and composition.This includes abundances of the major and minor species, the hunt for newgaseous species, isotope ratios for major species, and dynamics.CIRS may also be able to sense the surface near 600 cm-1. Allocationof time for Titan observations was primarily done in the TOST group(Titan Orbiter Science Team), in conjunction with recommendations fromthe AWG.CIRS can achieve different science goals at different distances fromTitan. Typically, CIRS makes the following requests (symmetric aboutclosest approach):+ 0 to +10 mins HIRES surface mapping (e.g. slew over south pole).+10 to +45 mins FIRLMBT - radial limb scans with FP1 to derive temperatures in the 8--100 mbar region via the N2-N2 collision-induced absorption between 20--100 cm-1.+45 to +75 mins FIRLMBAER - radial limb scans with FP1 to measure/ characterize particulate and condensate distributions, abundances and properties.+75 to +135 mins FIRLMBINT - integrate at two altitudes on the limb with FP1 to search for signals of CO, H2O and new species.+2:25 hrs to +5 hrs FIRNADMAP - slow scan north-south or east-west on the disk to sound tropospheric temperatures at 40--200 mbar, via the N2-N2 absorption, OR, slow scans at constant emission angle on the disk, to retrieve surface temperatures in the presence of aerosols around 520 cm-1.+5 to +9 hrs MIRLMBMAP - map 1/4 limb using the FP3 and FP4 arrays, to infer stratospheric temperatures via the 1304 cm-1 band of CH4. The arrays are placed perpendicular to the limb at two altitudes, chosen to provide overlapping coverage of the altitude range 150 to 420 km. The arrays are used in blink (ODD-EVEN) mode. After mapping both altitudes, the arrays are stepped 5 degrees in latitudes for the next step. OR, MIRLMBINT - as in MIRLMBMAP, except that only a single latitude is covered, at two over-lapping altitudes for 2 hrs in each position. To search for and measure new species in the mid-IR: methyl, benzene etc+9 to +13 hrs FIRNADCMP - integrate on the disk at emission angle approximately 60 degrees with the FP1 detector, in order to measure spatial abundance distribution of weak species and search for new species in the far-IR.+13 to +22 hrs MIDIRTMAP - scan the entire visible disk with the FP3/FP4 arrays perpendicular to the scan direction ('push-broom'), to measure stratospheric temperatures via the CH4 v4 band. Used for later dynamical analysis, for winds, waves etc.+22 to +48 hrs COMPMAP or TEMPMAP - map a meridian across the planet either E-W or N-S, using the Fp3/FP4 arrays in two positions longwise. To search for new species, and/or monitor temperatures.ICY SATELLITESSurface mapping in the IR, providing information on the surface composition,morphology, and age. Close passes of icy satellites resulted in timeallocated to the SOST (Satellites Orbiter Science Team), which dividedthe time between teams. There was also input from the Surfaces WorkingGroup (SWG).During the Cassini tour, there are eight flybys of the classical icysatellites targeted at 1000 km or less, as well as a number of'Voyager-class' (less than 300,000 km) encounters. There are alsoflybys of several much smaller satellites, such as Janus andEpimetheus, at various distances. The dimensions of these objectsrange from less than 100 km to as much as 1530 km (for Rhea).Consequently, it is most useful to discuss CIRS observations in termsof the angular diameter of the object, rather than its distance fromthe spacecraft.Normally the spacecraft orientation is controlled by momentum wheels,which provide pointing accuracy and precision of ~2 mrad and ~0.04mrad, respectively. Consequently, the full spatial resolution of theFP3 and FP4 pixels (0.3 mrad) cannot be utilized with reasonableconfidence until the target exceeds 1 mrad in diameter. At thatpoint, the separation of focal planes 3 and 4 (0.9 mrad), and thelarge size of FP1 (nominally 3.9 mrad) offer reasonable assurance ofobtaining useful data in either FP1 or at least one of FP3 and FP4.As with the planet and the rings, the order of magnitude difference inFOV scale between FP1 and the other focal planes plays heavily in thedesign of the icy satellite observations. Approaching from adistance, CIRS observations might proceed roughly in the followingorder. FP1INT, FP34INT: Compositional integrations (typically performed at ranges where the target AD is 1-3 mrad). Because spectral features of solid materials are generally broader than those of molecular lines, these observations are made at 1-3 cm-1 resolution. Conducted in staring mode, using FP1 and center detectors of FP3 and FP4, these are concentrated in geometries with low phase angles, so as to view the icy satellite surfaces at their warmest and maximize the signal-to-noise ratio. The steep rolloff of intensity with increasing wavenumber requires increasing integration time to extend the spectrum. For a 100K surface and a spectral resolution of 3 cm-1, a SNR of 10 at 600 cm-1 can be obtained with 1 minute of integration, but extending the spectrum to 800 cm-1 with the same SNR requires integration of 100 minutes Therefore, extending the spectrum to the highest wavenumbers will involve coadding spectra over the entire tour. SECLN, SECLX: Satellite eclipse entry (N) or exit (X) observations (AD>1 mrad, phase angle phi <100 degrees, spectral resolution delv : 15.5 cm-1; a typical eclipse duration is ~2 hours). The high sensitivity of FP1 permits observations of objects even when the FOV is incompletely filled, or when the phase angle is moderately high. At low phase angles, even FP3 can be used to follow the initial portion of the cooling curve for relatively dark objects; this allows observations with body-centric spatial resolution better than 10o to be made when the apparent target size exceeds ~3 mrad. Eclipses provide the thermal inertia of the upper mm or so of the surface, as well as estimates of surface coverage by relatively large fragments of consolidated material. FP1FAZ: Phase/longitude (diurnal cycle) coverage (AD>1 mrad, delv:15.5 cm-1, 10-20 minutes). Focal plane 1 will be utilized to determine the disk-averaged temperature of the satellites. From the resulting diurnal behavior, mean thermal inertias in the upper cm or so of the surface will be derived. FP34FAZ, FP34MAP, FP34REG: Global thermal inertia mapping and/or hot spot monitoring (AD>3 mrad, delv:15.5 cm-1). Maps are made by slewing and rastering FP3 and FP4 across the disk at rates not to exceed that for Nyquist sampling (16 microrad/sec in blink mode); observation durations will typically be 10-30 minutes. These maps will be successful for varying portions of a satellite, depending on its albedo and thermal inertia. The exception is Enceladus, which is so cold that even the subsolar regions will be barely detectable in an individual measurement. In this case, mapping will serve to monitor the satellite for ongoing endogenic activity; for example, active sources at or above the NH3.H2O eutectic temperature will be easily observed if they fill more than a few percent of an FP3 or FP4 pixel. FPGREEN: Search for a solid state greenhouse (AD>10 mrad, phi <40 degrees, delv :15.5 cm-1, 15 minutes). The decreasing absorption coefficient of water ice with decreasing wavenumber in the far-IR permits detection of radiation from increasingly far below the surface, reaching as deep as 1 cm at 10 cm-1. Slow east-west slews using FP1 allow following the daily penetration of the thermal wave into the regolith. FP1POLE: Polar night (annual cycle) coverage (AD>10 mrad, delv:15.5 cm-1, 15 minutes). FP1 observations of the dark winter polar region from high latitude permit determination of the seasonal cooling curve. This enables an estimate of thermal inertia in the upper tens of cm of the polar regolith. FP1DAYMAP, FP1DRKMAP: Hemispheric FP1 mapping near closest approach (AD>10 mrad, delv:15.5 cm-1). The high sensitivity of FP1 permits rapid mapping of satellite disks near closest approach, where time is at a premium. Nyquist-sampled maps at low spectral resolution (slew rate 400 microrad/sec) will typically take 10-30 minutes. These permit identification of minor thermal anomalies, even on the night hemisphere.Other TWT and WGsThe cross-discipline TWT (XD TWT) allocated time near apoapse on somerevs. The magnetospheres TWT allocated critical time for magnetosphericobservations, such as time near critical transition boundaries.Instrument Overview-------------------CIRS consists of two interferometers; a far-IR polarizing interferometersensitive from 10-600 cm-1, and a mid-IR interferometer sensitive from 600-1400 cm-1. The far-IR radiation is sensed by a large (~4 mrad diameter)thermopile detector (actually two, one for reflected and one fortransmitted beam at the polarizer/analyzer), known as FP1. The mid-IRradiation falls on two 1X10 arrays, known as focal planes 3 & 4. FP3is an array of photoconductive detectors sensitive from 600-1100 cm-1,and FP4 is an array of photovoltaic detectors sensitive from 1100-1400 cm-1.FP2 was dropped from the original design.Each of the 1X10 arrays has a 5-channel amplifier/signal processor, meaningthat only 5 of the 10 detectors in each array can be used at a time. Themaximum number of simultaneous interferograms from CIRS is therefore 11(1 from FP1, 5 from FP4, 5 from FP4). However, there are observing modesin which some of the focal planes are not used, leading to a lesser numberof active channels.Almost the entire instrument is thermostated to 170 K, including theprimary and secondary mirrors, internal optics, scan mechanisms, and the FP1focal plane assembly. The only exception is the FP3 and FP4 arrays (themid -IR FPA), which are cooled by a passive radiator to between 74 and 85K.See the INST.CAT file for full details.Calibration Overview--------------------Wavelength calibration is achieved by use of a reference diode laserinterferometer which uses the same scan mechanism as the IRinterferometer. Careful attention must be paid to the laser mode andvoltage which may drift/mode jump.Radiometric calibration in the far-IR (FP1) is simplified due to thefact that there is only one temperature inside theinstrument. Therefore, use of a deep space (2.7 K) reference target issufficient to calibrate radiance.The fact that the mid-IR has two temperatures to contend with meansthat a second reference target is required. Therefore, in the mid-IRoptical path, a shutter may be lowered for calibration purposes, whichgives a 170K reference body.Calibration must be done using complex number algebra and Fouriertransforms, to correctly account for phase changes which occur in thebeamsplitter. See the DATASIS.PDF for details.Parameters----------The major parameters when observing with CIRS are as follows:1) mid-IR shutter (open or closed). This is used for radiometriccalibration in the mid-IR, which requires two thermal referencebodies (space and shutter).2) mid-IR focal plane temperature set point (74-85 K). This wasusually set to the lowest level in the range at which the radiatorcould cope with heating from the sun and/or Saturn/rings, andtherefore, achieve stability of FPA temperature.3) FP3 pixel mode (ODD, EVEN, CENTER, PAIRS). Odd mode: detectors1,3,5,7,9 active. Even mode: detectors 2,4,6,8,10 active. Center mode:detectors 3,4,5,6,7 active. Pairs mode: 1&2, 3&4, 5&6, 7&8, 9&10signals combined and amplified.4) FP4 pixel mode (ODD, EVEN, CENTER, PAIRS). As FP3 modes, exceptthat detectors 4,5,6,7,8 used in CENTER mode, to spatially match thedetectors of FP3 which are numbered in reverse physical order.5) co-add mode (COADD or NO-COADD). In co-add mode, two successivescans are added together in the on-board electronics (buffers), toreduce the data rate by half.Data----This dataset is composed of CIRS Time Sequential Data Records,CIRS Spectral Image Cubes and related calibration software.READOUT, DOWNLINK AND DECOMPRESSIONCIRS data is normally read out at a rate of 4 kilobits per second(kbs) and 8kbit packets are transferred via the Bus Interface Unit(BIU) to the spacecraft Command Data Subsystem (CDS) every 2 seconds.CIRS has many ways of reducing data rate, such as co-adding IFMs(reduces rate by factor 2), dropping FP3 or FP4 readout (reduces by45%), dropping FP3 and FP4 readout (reduces by 91%), or going tohousekeeping only mode.Data packets are compressed in the instrument electronics, packetizedon the spacecraft, transmitted to the Earth via the Deep Space Network(DSN) and then decompressed by software on the ground. At this stage,the data goes into a processing pipeline, which organizes the sciencedata into binary tables and interpolates housekeepingrecords. Pointing and geometry tables are also produced when the NAIFdata becomes available.VANILLA PROGRAM FOR READING TABLESThe data is in the form of binary tables, also known as theVanilla database. Vanilla is a simple database access tool,also included on each volume as both source and executable.Note however that the Vanilla software is NOT REQUIRED in orderto read the binary data, but it may simplify the task. Notably,Vanilla links together all binary files into a huge, `logical'table, which can be searched based on key fields.However, the user may read the binary data directly, using anyprogramming language desired. If this approach is taken it isextremely important to pay attention to binary field widths:field widths vary, and typically trying to read an entire recordinto a data structure will fail: due to assumed padding of fields.The user must read the data in field by field, specifying width.Field widths are described in the *.FMT files, which are placedin each data directory.Some tables have both fixed-length and variable-length fields.In this case, the variable length part of the record is storedseparately, in a file with the same name but an extension .VAR,instead of .DAT. The third type is file extension is .LBL, whichis the PDS detached label.DATA LEVELSThe level-0 tables (base level) are contained in /DATA/TSDR/UNCALIBR.These are described in detail in the document DATASIS.PDF(DATASIS.TEX). These table types (IFGM, OBS, IHSK, FRV) are essentiallythe raw-level information which came from the instrument: theonly process applied was unpacking (uncompressing) the instrumentpackets and, in the case of the housekeeping data, interpolatingthe 64-sec interval housekeeping data onto the science scan intervals.Original housekeeping data is stored in /DATA/TSDR/HSK_DATA, which is readout at 64-sec intervals when the instrument is either ON or in SLEEP mode.Pointing and geometry information is stored in /DATA/TSDR/NAV_DATA.These tables are described in detail in the DATASIS document, andalso in the FMT format files in the NAV_DATA area. Primarily, thesestore the spacecraft attitude and position with respect to major bodies(GEO file type), the position of the 11 detectors (9 Q-points,or fiducial reference marks) on all bodies in the FOV (POI filetype), and the list of bodies seen in each detector (TAR type).Pointing and geometry information is derived from the spacecraftre-constructed attitude ('C') and trajectory ('SPK') kernels, usingNAIF (Navigation and Ancillary Information Facility) toolkit routinessupplied by JPL.Apodized calibrated spectra are stored in /DATA/TSDR/APODSPEC.Apodization is the process of mathematical filtering or smoothingwhich removes `ringing' effects from finite-width mathematical FFTs,widening the instrument line shape in the process. Apodization willnormally use the Hamming function window, but other types may be usedand the type will be given in the tables.CUBESSpectral Image Cubes are generated by systematic processingof the calibrated spectra. These data products are describedin detail in the document CUBESIS.PDF.Cubes are generated using two types of projections : equirectangularand point-perspective. These are stored in DATA/CUBE/EQUIRECTANGULAR, DATA/CUBE/POINT_PERSPECTIVE and DATA/CUBE/RING_POLAR.

This volume represents a first attempt at calibrating the CIRS Jupiterdataset. Certain calibration problems are known to exist, inparticular, thermal drifts in the ATMOS02B map noticeable at the 1-2 Klevel, which are seen as 'striping'. Similar drifts are likely to bepresent in other areas. Hence, the absolute radiometric accuracy isunlikely to be better than 1%. If a way is found to adequately removethese effects, it is envisaged that a second edition of the data wouldbe produced. The spectral calibration is thought to be accurate toapproximately 0.1 cm-1. NOTE ON INTERFERENCESCIRS interferogram data suffers from a number of external interferences,especially:- an 8 Hz spike pattern due to spacecraft communications and also to the onboard numerical filtering.- a 1/2 Hz spike pattern due to the Bus Interface Unit, transfer of data.- a sine wave of variable frequency which appears correlated with the electronics board temperature.- scan speed fluctuations which have been traced to two mechanical vibrations on the spacecraft: (a) the MIMI LEMMS actuator (b) the reaction wheels used to turn the spacecraft.- a 1 Hz spike pattern from the analog multiplexor data readouts.- an 8.3 Hz spike pattern from an unknown source.These various effects, plus the onboard and on-ground processing doneto mitigate them, are described in more detail in thecirs_interferences.pdf, CIRS-USER-GUIDE.PDF, and CirsNoise.pdf documentsfound in the DOCUMENT directory. PDS VERSION 2.0The entire CIRS dataset has been re-delivered as Version 2.0(DATA_SET_ID : CO-S-CIRS-2/3/4-TSDR-V2.0), which brings all previousvolumes up to the same calibration level.In this release, the AREA8HZSPIKE field in the UNCALIBR/DIAG table wasremoved and the following fields added: NAME : RATIO_SINE_8HZSPIKE NAME : ZPD_POS NAME : ZPDPEAK NAME : RAWPOWER NAME : DELTA_BIURTI NAME : FIFM_STD_DEV NAME : FIFM_ID NAME : TZPD NAME : TAMP NAME : ZPDENV NAME : AMPENV NAME : DCLEVELThere were some slight changes made to the calibration algorithm used toidentify blocks of deep space data. In those cases where a deep space datagap of more than an hour was found, a new minor block was created. Alsomodified, the deep space search window was increased from 4 hours to 8hours, and the maximum number of deep space interferograms allowed in ablock was increased to 5000. PDS VERSION 3.1The entire CIRS dataset was re-delivered as Version 3.1 (i.e., DATA_SET_ID: CO-S-CIRS-2/3/4-TSDR-V3.1). Following is a list of changes for each ofthe vanilla tables affected by this release. Descriptions for new fieldscan be found in the .FMT file for that table or in DATASIS.PDF.Table HSK_DATA/HSK: Field DECSPOSN changed from LSB_UNSIGNED_INTEGER (2 bytes) to PC_REAL (8 bytes). Field PHOTODIODE changed from LSB_UNSIGNED_INTEGER (2 bytes) to PC_REAL (8 bytes). The second IDSCALIB field has been renamed to IDSCALIB2.Table UNCALIBR/DIAG: New fields: NAME : RWA1_MIN NAME : RWA1_MAX NAME : RWA2_MIN NAME : RWA2_MAX NAME : RWA3_MIN NAME : RWA3_MAX NAME : RWA4_MIN NAME : RWA4_MAX NAME : RWA_NOISE_FLAGTable UNCALIBR/OBS: Eight new fields were added: NAME : SCET_MSEC NAME : COMPUTED_RTI NAME : CONSECUTIVE_NULL_SCANS NAME : IDS_MUX NAME : TCM_MUX NAME : PACKETIZATION_STATUS NAME : MSEC_SINCE_RTI NAME : FSVTable NAV_DATA/GEO: Changed TIME_ZPD from LSB_INTEGER to PC_REAL. It is now a time based on SCET, OBS.SCET_MSEC, and DIAG.TZPD. The field SCET_FRACTIONAL_SECONDS has been removed. The following fields were added: NAME : BODY_SUB_SPACECRAFT_LATITUDE_PC NAME : BODY_SUB_SOLAR_LATITUDE_PC NAME : PRIMARY_SUB_SPACECRAFT_LATITUDE_PC NAME : PRIMARY_SUB_SOLAR_LATITUDE_PCTable NAV_DATA/POI: Changed TIME_ZPD from LSB_INTEGER to PC_REAL. It is now a time based on SCET, OBS.SCET_MSEC, and DIAG.TZPD. The following fields were added: NAME : ZLIMB NAME : SPACECRAFT_BODY_FIXED NAME : FOV_BODY_FIXED NAME : Z NAME : LATITUDE_ZPD_PC NAME : LATITUDE_END_PCTable NAV_DATA/RIN: Changed TIME_ZPD from LSB_INTEGER to PC_REAL. It is now a time based on SCET, OBS.SCET_MSEC, and DIAG.TZPD. The fields RING_LONGITUDE_ZPD and RING_SOLAR_ZENITH are now defined for all Q points.In addition to the above, this release includes an algorithmic change.For interferograms collected using CIRS Flight Software Version 6 (executedin July of 2010), non-co-added data will have the 1/2 Hz noise spikessuppressed while no noise spike suppression will be done on co-added data. PDS VERSION 3.2The entire CIRS dataset was re-delivered as Version 3.2 (i.e., DATA_SET_ID: CO-S-CIRS-2/3/4-TSDR-V3.2). Following is a list of changes for each ofthe vanilla tables affected by this release. Descriptions for new fieldscan be found in the .FMT file for that table or in DATASIS.PDF.Table HSK_DATA/HSK: HSK.HSECOOLTEM: This field previously contained negative temperatures for five scans in 2005 and 2006. Each of those scans corresponds to an analog to digital conversion error when trying to sample the MUX channel which sets an error flag in housekeeping in the following packet. This was not being picked up in the previous version. Now the flag is checked and if set, HSK.HSECOOLTEM is set to -1.Table UNCALIBR/OBS: OBS.SCLK: Changed from LSB_UNSIGNED_INTEGER to PC_REAL. It represents the time equivalent of OBS.SCET + OBS.SCET_MSEC / 1000. OBS.SCET + OBS.SCET_MSEC / 1000. now represents the time of the first raw data sample. Because fractional seconds are now included in the SCLK to SCET conversion, going from v3.1 to v3.2 sometimes increases the SCET value by 1 second. This occurs when the fractional seconds, computed_rti, and msec_since_rti are combined to get a SCET_MSEC value greater than 999. NAIF SPICE kernels are now used to convert from SCLK to SCET in the OBS table. (Previously an epoch specified in the SFDU header was used.) This change in methods may produce a correction in the OBS.SCET value when calculations switch from using predict SCLK kernels to reconstructed kernels. OBS.SCAN_FLYBACK_MSEC: Added. Represents the time (in seconds) from the first raw data sample to the start of the mirror flyback. Implemented on board the instrument as of FSV 6.0.1. Before FSV 6.0.1, this field will be set to 0.Table UNCALIBR/IHSK: IHSK.HSECOOLTEM: The previous version allowed the use of negative HSK.HSECOOLTEM values when calculating the interpolated value IHSK.HSECOOLTEM. This version only uses non-negative values of HSK.HSECOOLTEM for the interpolation.Table NAV_DATA/GEO: GEO.TIME_ZPD: Calculation change. It now uses OBS.SCET, OBS.SCET_MSEC, and DIAG.TZPD, along with the focal plane dependent time delays associated with the numerical filter to find a much more accurate ZPD time (in the SCET time system). Time shifts of up to 3 seconds occur because of the change. GEO.SCLK: Changed from LSB_INTEGER (4 bytes) to PC_REAL (8 bytes).Table NAV_DATA/POI: POI.TIME_ZPD: Calculation change. It now uses OBS.SCET, OBS.SCET_MSEC, and DIAG.TZPD, along with the focal plane dependent time delays associated with the numerical filter to find a much more accurate ZPD time (in the SCET time system). Time shifts of up to 3 seconds occur because of the change. POI.SMEAR: Calculation change. The condition that the boresight hit the target in order to compute the SMEAR field has been removed. It will still compute the same value as in the previous version if the boresight hits the target, but the new version always computes the SMEAR. When it doesn't hit the target it now uses the ray periapsis rather than the intersection point. POI.Z: A bug in the code which used the wrong indices to calculate this field has been corrected.Table NAV_DATA/RIN: RIN.TIME_ZPD: Calculation change. It now uses OBS.SCET, OBS.SCET_MSEC, and DIAG.TZPD, along with the focal plane dependent time delays associated with the numerical filter to find a much more accurate ZPD time (in the SCET time system). Time shifts of up to 3 seconds occur because of the change.Table NAV_DATA/TAR: Three new targets have been added to the TAR table: Daphnis, Methone, and Pallene. These correspond to three new fields TAR.DAPHNIS, TAR.METHONE, and TAR.PALLENE. New bit fields in TAR.FOV_TARGETS have also been defined with bits 2^26, 2^27, and 2^28 represented by Methone, Daphnis, and Pallene, respectively.Table APODSPEC/ISPM: The selection criteria fields used in the compilation of calibration blocks are now detector, rti, coadd, shutter, laser mode (1,2,3,!:0), fpa setpoint, noise (!:1), fp1dettem, hsecooltem, fpatem, firpolriztem, npts, truezpd, rawpower, and flight software version. Previously, only detector, rti, coadd, fpa setpoint, noise (!:1) and optical sense mode were used. The following fields were added: NAME : CALIB_SCORE1 NAME : CALIB_SCORE2 NAME : CALIB_SCORE3 NAME : CALIB_SCORE4 NAME : CTZPD1 NAME : CTZPD2 NAME : DIST_DS_TZPD1 NAME : DIST_DS_TZPD2 NAME : DIST_DSSH_TZPD1 NAME : DIST_DSSH_TZPD2 NAME : DIST_SH_TZPD1 NAME : DIST_SH_TZPD2 NAME : DS_TDET NAME : DS_TINSTR NAME : DS_TZPD1 NAME : DS_TZPD2 NAME : FPASET NAME : LASER_WL NAME : PHASE_SHIFT NAME : HASE_SHIFT_ERROR NAME : PHASE_SHIFT_FLAG NAME : SH_TDET NAME : SH_TINSTR NAME : SH_TZPD1 NAME : SH_TZPD2 NAME : TDETNewly included in the archive are the spectral image cube dataset (V1.0)and the Titan atmosphere temperature, aerosol, and ice profiles. PDS VERSION 4.0The entire CIRS dataset was re-delivered as Version 4.0 (i.e., DATA_SET_ID: CO-S-CIRS-2/3/4-TSDR-V4.0). Following is a list of changes for each ofthe vanilla tables and algorithms affected by this release. Descriptionsfor new fields can be found in the .FMT file for that table or inDATASIS.PDF.The FP1 electrical interference spike suppression algorithm has beenimproved for 0.5 Hz and 8 Hz de-spiking, and 1 Hz de-spiking andsine wave suppression have been added.A new algorithm for detecting and characterizing velocity variations ininterferograms for both pre- and post-FSW 6.0.0 has been added.The algorithm examines the values of MECH_OUT_OF_PHASE, RWA_NOISE_FLAG, andNPTS to establish two levels of velocity variation disturbance: NOISE : 1('negligible' or 'mild' velocity variations) and NOISE : 4096 or 8192('severe' velocity variations).Made enhancements to the interferogram noise detector algorithm to moreeffectively identify and reject interferograms afflicted with a wide rangeof disturbances: spikes, drifts, DC level off, too few samples, too manysamples, incorrect ZPD position, and velocity variations.The number of samples (FPTS) assigned to filtered interferograms (FIFMs)for each focal plane and RTI has been refined. Every FIFM of a given focalplane and RTI is assigned the same value of FPTS, regardless of its NPTSvalue. In addition, 40 RTI interferograms are truncated to the values ofFPTS assigned to 39 RTI interferograms. Finally, all FP1 39 and 40 RTIinterferograms now have FPTS : 179 samples and are therefore symmetricabout the ZPD fringe at sample number : 89. These changes ensure thatall spectra of a given RTI have the same spectral resolution.Improved the power spectrum (RAWPOWER) of the symmetricaltwo-sided ZPD region of each interferogram. Focal plane 1 RAWPOWER is nowcalculated after the DC baseline and deep-space shape function are subtractedfrom the interferogram. The focal plane 3 RAWPOWER is calculated afterthe DC baseline is removed.There is a small difference in the way the laser value is being selected.For any FRV[2] value that fits between a minimum and maximum value(4 and 6.25, respectively), the laser mode is selected according to SCET.If it is outside the limits, the laser mode is set to 0.In previous versions, only scans with a noise value of 1 were written tothe FIFM tables. This version additionally allows all scans with noisevalues of 4096 and 8192 to be written to the FIFM table. If the noisevalue is other than 4096, 8192, or 1, the scan is written to the FIFMtable as having a length of 1 and a value of 0. This was done to allowthe scan to be included in the output of queries that include other tables.New calibration algorithm: The calibration of CIRS data requires the calculation of reference interferograms or spectra at 2 known temperatures, commonly referred to as 'cold' and 'hot'. For our instrument, the cold data is acquired by pointing at the cold deep space, away from any known target. The hot data is acquired by closing the shutter and looking at the structure of our instrument. As part of the science observation designs, the instrument team included time periods for the acquisition of these 2 types of reference data. Nominally, they would be included at least at the beginning and at the end of an observation, but if the observation is extended, the observation may have been designed to include additional calibration measurements during the observation. In CIRS volume deliveries before PDS version 4.0, to calibrate a given interferogram the algorithm was designed to find a contiguous block of reference data as near as possible in time to the interferogram and build a cold and a hot average. Because contiguity was a requirement, the averages would sometimes be based upon very few interferograms. For the current release, the algorithm was modified to use a much larger number of cold and hot calibration interferograms, removing the contiguity constraint and using up to 4,000 scans during a 3 month range about the acquisition time. The primary goal of increasing the number of scans in the hot and cold averages is to increase the signal-to-noise ratio. This release also includes a phase correction algorithm used to compensate sampling errors during acquisition of the interferograms. The interferogram sampling system is sensitive to external mechanical perturbations such as the spacecraft reaction wheel assembly. Under specific conditions, the opto-mechanical system controlling the moving mirror can trigger sampling away from the nominal position. The recorded interferogram is then time shifted, and its corresponding spectrum will have a baseline distortion. The phase correction algorithm predicts and identifies anomalous interferograms and applies a linear phase correction.Table UNCALIBR/DIAG: The following fields were added: NAME : PHASESINE NAME : RATIO_FWHM_HALF_HZ NAME : RATIO_WN_EIGHT_HZ NAME : RATIO_FWHM_EIGHT_HZ NAME : RATIO_EIGHT_HZ_SPIKE_AMPLITUDE NAME : IFM_DC_LEVEL NAME : STD_DEV_BEFORE_ZPD NAME : STD_DEV_ZPD_REGION NAME : STD_DEV_AFTER_ZPD NAME : DELTA_RTI_DIFFERENCE NAME : NOISE_DIAGNOSTIC NAME : AMPSINEWAVE NAME : AMP8HZSPIKE The RATIO_SINE_8HZSPIKE, DCLEVEL, ZPDPOS, AND ZPDPEAK fields were removed. The FIFM_ID field has been renamed as SPECTRUM_DIAGNOSTIC, however, FIFM_ID remains as an alias.Geometry/Pointing algorithm: The size of Titan's penumbra was previously increased (from a radius of target+600KM to a radius of target+1K KM), however, it created a problem during some observations where the spacecraft was inside the newly increased penumbra and the code marked those scans as being deep-space, as opposed to being Titan scans, which confused the calibration code. Now, when the body_spacecraft_range is smaller than the penumbra (i.e., radius of target + padding) the code ensures those scans are cataloged as the target and not deep-space. The following observations were affected by the penumbra change: CIRS_106TI_REGMAP001_VIMS on March 26-27, 2009 CIRS_106TI_REGMAP001_ISS on March 27, 2009 CIRS_106TI_HIRES001_VIMS on March 27, 2009 CIRS_138TI_GLOBMAP001_VIMS on September 24, 2010 CIRS_169TI_REGMAP001_VIMS on July 24, 2012 CIRS_169TI_HIRES001_VIMS on July 24, 2012 CIRS_169TI_HIRES002_VIMS on July 24, 2012 CIRS_169TI_FIRNADMAP002_PRIME on July 24-25, 2012 CIRS_169TI_MIRLMBMAP002_PRIME on July 27, 2012 Jupiter is now explicitly searched for in the field of view during the time period Cassini was in orbit about Saturn.Table NAV_DATA/TAR: Two new targets have been added to the TAR table: Polydeuces and Aegaeon. These correspond to two new fields TAR.POLYDEUCES and TAR.AEGAEON. New bit fields in TAR.FOV_TARGETS have also been defined with bits 2^29 and 2^30 represented by Polydeuces and Aegaeon, respectively. Changed the FOV_TARGETS field from 33554432 (rings) to 0 (deep space) when the RING_SPACECRAFT_RANGE_ZPD[5] field is negative, which means the rings are behind the spacecraft.New table, OISPM: During the calibration process, a filtering and noise detection algorithm is applied to the data to determine the quality of the interferograms. The algorithm looks for anomalies in the number of interferogram sample points (typically from scan mechanism velocity variations), dual zero phase difference (ZPD) peaks, and irregular sampling (see the NOISE field in DIAG table). While shortened interferograms or dual ZPD interferograms are not usable, interferograms with moderate sampling perturbations can produce calibrated spectra, but they may be of lower quality or noisier than spectra calibrated without anomalies. To ensure users of these lower quality spectra are aware of the data's limitations, a new table, OISPM, has been created and placed in a directory (DATA/TSDR/SUSPECT_SPECTRA) separate from the nominal spectra, forcing it to be queried independently of the ISPM tables. Also critical to the calibration process, the temperature of the focal plane assembly (IHSK.FPATEM) of the mid-infrared focal plane assembly (FPA) must be taken into account. This temperature is defined by the thermal balance between the 70K cooler and a heater placed near the detectors. During a CIRS observation, the temperature of the FPA is set to one or more of a discrete set of values where each value (set point) corresponds to a temperature range of 0.4 K about values spaced 0.75 K apart. If the instrument is not thermally stable or if the sun, Saturn, or Saturn's rings illuminate the FPA radiator, the FPA may not be operating at a nominal, steady, controlled temperature. Because the mid-infrared detector responsivities are dependent on the FPA temperature, in order to be properly calibrated, target interferograms should be matched with averages of deep space data acquired at the same FPA temperature (set point). If the target and deep space interferogram FPA temperatures cannot be matched, nearby deep space data (in time) at a different temperature will be used, with the resulting calibrated spectra placed in the OISPM table. There are several additional cases in which the calibration of an interferogram was determined to be questionable, causing its spectrum to be placed in the OISPM table: 1. The calibration accuracy is dependent on the number of deep space interferograms averaged together. If too few are available, the noise increases to unacceptable levels, and the spectrum becomes suspect. 2. During the mission, the laser state (DIAG.LASER) changed modes several times which caused some instrument recording modes to have little or no reference data. Calibrating target data with reference data from a similar, but different, instrument mode caused small mismatches in the wavelength scale. 3. A subset of the data used a mode for which interferograms were co-added time-wise. This sometimes affected the noise spike pattern making it difficult for the de-spiking algorithm to do its job. This was exacerbated if no co-added reference data was available.