Data Set Overview : This data set contains the Infrared Thermal Mapping (IRTM) data of Mars acquired by the Viking orbiters. The database contains the time, geometry, and radiative parameters obtained by the IRTM instrument. Included in the database for each measurement are model temperatures of Mars; this model attempts to represent the average Martian response to the temporal variation of insolation. The reference 'Thermal and Albedo Mapping of Mars during the Viking Primary Mission', Journal of Geophysical Research, Vol. 82, No. 28, 1977, describes how the thermal emission and reflected energy measured by the various channels on the Infrared Thermal Mapper are used to reveal wide variations in the Martian surface properties. There is a description of how the surface thermal inertias are mapped and correlated with the surficial geologic units. The derivation of model and surface temperatures are described. The data set includes latitude and longitude for each measured point, as well as emission angle, solar incidence angle, the position of the sun, and other parameters that help to locate the position of the spacecraft relative to Mars. (For further information see the Confidence_Level_Note).  Processing Level Id : 4 Software Flag : Y Processing Start Time : 1976 Processing Stop Time : 1980 Native Start Time : 415147712 FDSC Native Stop Time : 964559552 FDSC   Parameters :  Data Set Parameter 'BRIGHTNESS TEMPERATURE' ------------------------------------------- The kinetic temperature of an ideal blackbody which, if observed with the spectral response of the instrument spectral channel in question would yield the observed radiance.  Data Set Parameter Name : BRIGHTNESS TEMPERATURE Data Set Parameter Unit : KELVIN Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : 1.12 Sampling Parameter Interval : 1.12 Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'DERIVATIVE OF MODEL WITH ALBEDO' ---------------------------------------------------- The differential dependence of model temperature upon the assumed surface bolometric bond albedo, at the nominal value of model thermal inertia.  Data Set Parameter Name : DERIVATIVE OF MODEL WITH ALBEDO Data Set Parameter Unit : DEGREES Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : N/A Sampling Parameter Interval : N/A Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'DERIVATIVE OF MODEL WITH INERTIA' ----------------------------------------------------- The differential dependence of model temperature upon the assumed surface thermal inertia, at the nominal value of model bolometric bond albedo.  Data Set Parameter Name : DERIVATIVE OF MODEL WITH INERTIA Data Set Parameter Unit : KELVIN / (10**(-3)*CAL*CM**(-2)*S**(-1/2)*K**(-1)) Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : N/A Sampling Parameter Interval : N/A Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'LAMBERT ALBEDO' ----------------------------------- The reflectance of a grey Lambert (ideal diffuse) smooth surface parallel to the target body geoid which would yield the observed reflected radiation in the absence of any atmosphere.  Data Set Parameter Name : LAMBERT ALBEDO Data Set Parameter Unit : N/A Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : 1.12 Sampling Parameter Interval : 1.12 Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'MINNAERT ALBEDO' ------------------------------------ Albedo computed presuming a Minnaert behavior, with the Minnaert exponent k equal to 0.95. A_m : Visual_Brightness * cos(incidence angle)**-k * cos(emission angle)**(1.-k).  Data Set Parameter Name : MINNAERT ALBEDO Data Set Parameter Unit : N/A Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : 1.12 Sampling Parameter Interval : 1.12 Minimum Available Sampling Int : 1.12 Noise Level : N/A   Data Set Parameter 'MODEL TEMPERATURE' -------------------------------------- The surface kinetic temperature calculated using a nominal set of parametric values for a smooth planet of uniform physical properties and for the latitude, time of day, and season of the observation. The model used for the Viking IRTM is described in the appendix of [KIEFFER_ETAL_1977].  Data Set Parameter Name : MODEL TEMPERATURE Data Set Parameter Unit : KELVIN Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : N/A Sampling Parameter Interval : N/A Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'PHASE CORRECTED ALBEDO' ------------------------------------------- Albedo computed using a phase dependence derived from IRTM observations (See [KIEFFER_ETAL_1977]). A_g : A_l * (1.+0.000146*exp(0.075*phase_angle) where A_l : Visual_brightness / cos(incidence angle)  Data Set Parameter Name : PHASE CORRECTED ALBEDO Data Set Parameter Unit : N/A Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : 1.12 Sampling Parameter Interval : 1.12 Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'SINGLE POINT THERMAL INERTIA' ------------------------------------------------- The thermal inertia which would yield the observed brightness temperature, based on the observed Lambert albedo, the model temperature and partial derivatives of model temperature with albedo and inertia, and an approximation of the non-linear dependence of model temperatures with respect to thermal inertia. If the observation was at night, so that no measure of albedo was made, the albedo is assumed to be the same as in the nominal thermal model.  Data Set Parameter Name : SINGLE POINT THERMAL INERTIA Data Set Parameter Unit : 10**(-3)*CAL*CM**(-2)*S**(-1/2)*K**(-1) Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : N/A Sampling Parameter Interval : N/A Minimum Available Sampling Int : N/A Noise Level : N/A   Data Set Parameter 'VISUAL BRIGHTNESS' -------------------------------------- The radiant energy measured in the IRTM solar band (0.3-3.0 microns), normalized to that expected for an ideal Lambert reflector observed under normal incidence at the current heliocentric range of the target body.  Data Set Parameter Name : VISUAL BRIGHTNESS Data Set Parameter Unit : WATT/(METER*METER)/STERADIAN Sampling Parameter Name : TIME Sampling Parameter Unit : SECOND Minimum Sampling Parameter : N/A Maximum Sampling Parameter : N/A Sampling Parameter Resolution : 1.12 Sampling Parameter Interval : 1.12 Minimum Available Sampling Int : N/A Noise Level : N/A   Source Instrument Parameters : Instrument Host ID : VO1 Data Set Parameter Name : MODEL TEMPERATURE Instrument Parameter Name : N/A Important Instrument Parameters : 0  Instrument Host ID : VO2 Data Set Parameter Name : MODEL TEMPERATURE Instrument Parameter Name : N/A Important Instrument Parameters : 0  Instrument Host ID : VO1 Data Set Parameter Name : DERIVATIVE OF MODEL WITH ALBEDO Instrument Parameter Name : N/A Important Instrument Parameters : 0  Instrument Host ID : VO2 Data Set Parameter Name : DERIVATIVE OF MODEL WITH ALBEDO Instrument Parameter Name : N/A Important Instrument Parameters : 0  Instrument Host ID : VO1 Data Set Parameter Name : DERIVATIVE OF MODEL WITH INERTIA Instrument Parameter Name : N/A Important Instrument Parameters : 0  Instrument Host ID : VO2 Data Set Parameter Name : DERIVATIVE OF MODEL WITH INERTIA Instrument Parameter Name : N/A Important Instrument Parameters : 0  Instrument Host ID : VO1 Data Set Parameter Name : LAMBERT ALBEDO Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : LAMBERT ALBEDO Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : MINNAERT ALBEDO Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : MINNAERT ALBEDO Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : VISUAL BRIGHTNESS Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : VISUAL BRIGHTNESS Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE A Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE A Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE B Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE B Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : PHASE CORRECTED ALBEDO Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : PHASE CORRECTED ALBEDO Instrument Parameter Name : RADIANCE D Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE C1 Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE C1 Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE C2 Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE C2 Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE C3 Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : BRIGHTNESS TEMPERATURE Instrument Parameter Name : RADIANCE C3 Important Instrument Parameters : 1  Instrument Host ID : VO1 Data Set Parameter Name : SINGLE POINT THERMAL INERTIA Instrument Parameter Name : RADIANCE A Important Instrument Parameters : 1  Instrument Host ID : VO2 Data Set Parameter Name : SINGLE POINT THERMAL INERTIA Instrument Parameter Name : RADIANCE A Important Instrument Parameters : 1   Processing :  Processing History ------------------ Source Data Set ID : TSDR Software : XG SYSTEM Product Data Set ID : VO1/VO2-M-IRTM-4-V1.0   Software 'XG SYSTEM' -------------------- Retrieves and analyzes data from the Viking 1 and 2 Infrared Thermal Mapper Data (IRTM) and Mars Atmospheric Water Detector (MAWD) databases. Data variables may be printed, plotted, or mapped while applying constraints to time, geometry or the variables themselves.  Software Name : XG SYSTEM Software Type : N/A Software Release Date : 1989-02-28 Node ID : RADIOMETRY Cognizant Engineer : DEBBIE A. COOK Software Access Description : NOT ACCESSIBLE THROUGH PDS CATALOG - CONTACT NODE.

Overview : Initially in the mission, orbit updates were done daily; later, they were done only once a week. Therefore at some times, the precise position of the spacecraft was not known accurately enough to calculate the position of the spacecraft around Mars. These timing offsets in the position of the spacecraft in turn introduced errors in latitude and longitude of the thermal observations. The user should be aware of these discrepancies in latitude and longitude, which affect primarily near-periapsis data late in the mission. The following is a description of event and error flags that are captured in the quality word definition for each 1.12 second interval (the time between successive measurements known as ICK).  QUALITY WORD DEFINITION  Bit flags pertaining to the data at the corresponding time (ICK). Bits are numbered from least significant to most significant, 0 to 15. Bits 0 through 9 represent conditions at the time of observation, and do not necessarily imply poor quality. Bits 11-14 form a sequence of data quality indicators, from good (all 4 bits off) to terrible (bit 14 on). Thus the word itself may be used in an algebraic quality test. (QUAL < 2048 : 2**11 if data must be of best quality)  VAL BIT  1 0 DC restore has just occurred in the IRTM instrument 2 1 Scan platform is in motion 4 2 Telemetry was used for pitch, roll and yaw computations 8 3 Telemetry was used for cone and clock computations 16 4 Image motion compensation geometry correction required 32 5 Geometry corrected unless bit 14 is on 64 6 Cone slew rate less than or : 1/8 deg/ICK (.1 deg / sec) 128 7 Clock slew rate GE 1/8 deg/ICK (.1 deg/sec) 256 8 Cone slew direction negative 512 9 Clock slew direction negative 1024 10 VO-2 anomaly correction applied (orbits 55-84) (bit 13 also set) or quadratic fit used for space values (VO-2 orbits greater than 84) 2048 11 Some channel(s) despiked 4096 12 Uncertainty < 8 DN for some channel(s) but missing space value or high drift rate 8192 13 VO-2 encoder dc restore on reference plate (visual band data probably OK) 16384 14 Uncertainty 7 DN or greater for some channel(s) due to missing space value or high drift rate or imaging sequence with only 1 space look 32768 15 Totally bad data at this ICK - do not use