PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM SPACECRAFT_NAME = "INFRARED ASTRONOMICAL SATELLITE" INSTRUMENT_NAME = "FOCAL PLANE ARRAY" INSTRUMENT_ID = "FPA" OBJECT = TEXT NOTE = "Definitions of PDS keywords used in the data labels, listed in alphabetical order." PUBLICATION_DATE = 2003-05-29 /* Preliminary Review Date */ END_OBJECT = TEXT END PDS Keyword Definitions ======================= NAME = B1950_DECLINATION UNIT_ID = DEGREE MINIMUM = -90.000000 MAXIMUM = 90.000000 DESCRIPTION = The B1950_declination element provides the declination of the target using the B1950 coordinate frame rather than the J2000 frame. IRAS used the B9150 coordinate frame. For an IRAS Tempel 1 image, B1950_DECLINATION refers to the declination assigned to the pixel at the center of the image. NAME = B1950_RIGHT_ASCENSION UNIT_ID = DEGREE MINIMUM = 0.000000 MAXIMUM = 360.000000 DESCRIPTION = The B1950_right_ascension element provides the right ascension of the target object using the B1950 coordinate frame rather than the J2000 frame. IRAS used the B9150 coordinate frame. For an IRAS Tempel 1 image, B1950_RIGHT_ASCENSION refers to the declination assigned to the pixel at the center of the image. NAME = DATA_SET_ID DESCRIPTION = The data_set_id element is a unique alphanumeric identifier for a set of data. The data_set_id is an abbreviation of the data_set_name. For IRAS Tempel 1 data, the convention for constructing data_set_id is IRAS-rr-FPA-dd-xx-TEMPEL1-DI-V1.0, where rr = Type of the target = C for comet FPA = Instrument = FPA for focal plane array dd = Processing level = 5 for derived data and 6 for ancillary data such as calibration files xx = Data set type, such as AOIMAGE for IRAS Additional Observation images or SSPHOT for IRAS Survey Scan photometry files TEMPEL1 = specific target DI = Deep Impact mission that initiated this archive V1.0 = Version 1.0 of the data set NAME = DATA_SET_NAME DESCRIPTION = The data_set_name element provides the full name given to a set of data. The data_set_name identifies the instrument that acquired the data, the target of that instrument, and the processing level of the data. NAME = DERIVED_MAXIMUM DESCRIPTION = The derived_maximum element indicates the largest value occurring in a given instance of the data object after the application of a scaling factor and/or offset. NAME = DERIVED_MINIMUM DESCRIPTION = The derived_minimum element indicates the smallest value occurring in a given instance of the data object after the application of a scaling factor and/or offset. NAME = EXPOSURE_DURATION UNIT_ID = SECOND DESCRIPTION = For an IRAS Tempel 1 Additional Observation image, the exposure_duration element provides the is the actual time observing the target and is part of observation_duration. For an IRAS Tempel 1 Survey Scan image, exposure_duration is the total time observing the target for all scans used to make the image mosaic. NAME = FILE_NAME DESCRIPTION = The file_name element provides the location independent name of a file. It excludes node or volume location, directory path names, and version specification. To promote portability across multiple platforms, PDS requires the file_name to be limited to an 27-character basename, a full stop (. period), and a 3-character extension. Valid characters include capital letters A - Z, numerals 0 - 9, and the underscore character (_). NAME = FILE_SPECIFICATION_NAME DESCRIPTION = The file_specification_name element provides the full name of a file, including a path name, relative to a PDS volume. It excludes node or volume location. Path names are limited to eight (8) directory levels, and are separated by the forward slash (/) character. Each directory is limited to 8 characters chosen from the set {A-Z, 0-9,_}. The path is followed by a valid file name. See also: file_name. NAME = INCLINATION_OBSERVATION MINIMUM = 0.000000 MAXIMUM = 360.000000 DESCRIPTION = " the inclination of an observation with respect to a non-standard coordinate system. For IRAS: The IRAS satellite has a natural, non-standard, coordinate system defined by solar_elongation and inclination_observation. Solar_elongation is the angle between the line of site and the Sun. Inclination_observation is the angle between the ecliptic plane and the plane containing the Earth, Sun, and the observation direction (that is, the azimuth angle about the Earth-Sun axis). The value is zero when IRAS looks at the ecliptic plane in the direction opposite to the motion of the Earth around the Sun. The value increases clockwise around the Earth-Sun axis when facing the Sun, and opposite from the direction of the motion of the satellite in its polar orbit about the Earth. Inclination_observation is related to iras_clock_angle by the relation: inclination_observation = 90 - iras_clock_angle. Solar_elongation and inclination_observation are related to geocentric ecliptic latitude (beta) and longitude (lamda) and the longitude of the Sun (lamda Sun) through the relations: sin(inclination_observation) = sin(beta)/sin(solar_elongation) cos(solar_elongation) = cos(beta)*cos(lamda - lamda Sun). PDS defines iras_clock_angle as the satellite viewing angle projected onto the plane perpedicular to the Sun- line, measured from ecliptic North, clockwise as viewed from the Sun. This is the same direction as the IRAS orbital motion. NAME = INVALID_CONSTANT DESCRIPTION = The invalid_constant element supplies the value used when the received data were out of the legitimate range of values. NAME = LINE_DISPLAY_DIRECTION DESCRIPTION = The line_display_direction element is the preferred orientation of lines within an image for viewing on a display device. The default value is down, meaning lines are viewed top to bottom on the display. See also SAMPLE_DISPLAY_DIRECTION. NAME = MAXIMUM_TARGET_RADIANCE_LINE DESCRIPTION = For IRAS Additional Observation and Survey Scan images, the maximum_target_radiance_line identifies the line that contains the pixel of maximum radiance from the target. See also MAXIMUM_TARGET_RADIANCE_SAMPLE. NAME = MAXIMUM_TARGET_RADIANCE_SAMPLE DESCRIPTION = For IRAS Additional Observation and Survey Scan images, the maximum_target_radiance_sample identifies the sampe (row) that contains the pixel of maximum radiance from the target. See also MAXIMUM_TARGET_RADIANCE_SAMPLE. NAME = MEAN_OBSERVATION_DURATION DESCRIPTION = The MEAN_OBSERVATION_TIME is the average date and time associated with an observation that itself consists of recording mutiple events (photon arrival times, for example). It is distinct from OBSERVATION_TIME, which is the midpoint of the observation period, in that it is calculated by taking the arithmetic average of all event times associated with the single observation. For IRAS Additional Observation (AO) images, this is the observing time spent on the target. The rest of the time was used to make fine attitude updates on reference stars at the begining and at the end of an AO. See also EXPOSURE_DURATION. For Survey Scan (SS) images, this is the mean of NAME = NOT_APPLICABLE_CONSTANT DESCRIPTION = The not_applicable_constant element supplies the numeric value used to represent the figurative constant 'N/A'. 'N/A' (Not Applicable) is defined as indicating when values within the domain of a particular data element do not apply in a specific instance. NAME = OBSERVATION_DURATION DESCRIPTION = The observation_duration element provides the value of the total time interval for one observation. For an IRAS Tempel 1 Additional Observation (A0) image, observation_duration includes the total duration of the observation, including time observing the target (see exposure_duration) and time used to make fine attiiude updates on reference stars at the begining and at the end of an AO. NAME = OBSERVATION_ID DESCRIPTION = The observation_id element identifies a scientific observation within a data set. For an IRAS Tempel 1 Additional Observation, the observation_id is in the form SOP.OBS where SOP is the satellite observation plan number and OBS is the observation number within the plan. For an IRAS Tempel 1 Survey Scan, the observation_id is simply SOP where SOP is the satellite observation plan number. NAME = PHASE_ANGLE UNIT_ID = DEGREE MINIMUM = 0.000000 MAXIMUM = 180.000000 DESCRIPTION = The phase_angle element provides a measure of the relationship between the instrument viewing position and incident illumination by solar light. Phase_angle is measured at the target; it is the angle between a vector to the illumination source and a vector to the instrument. If illumination is from behind the instrument, phase_angle will be small. NAME = PROCESSING_HISTORY_TEXT DESCRIPTION = The processing_history_text element provides an entry for each processing step and program used in generating a particular data file. NAME = PROCESSING_LEVEL_ID DESCRIPTION = The processing_level_id element identifies the processing level of a data file. For IRAS Tempel 1 data, the value 1 identifies the first iteration of the reduction process. The final, best iteration is identified by a value between 14 and 40. NAME = PRODUCT_ID DESCRIPTION = The product_id data element represents a permanent, unique identifier assigned to a data product by its producer. NAME = PRODUCT_NAME DESCRIPTION = The PRODUCT_NAME element provides the full name of a product. It is related to product_id and provides a brief, descriptive title for a particular data product. NAME = SAMPLE_DISPLAY_DIRECTION DESCRIPTION = The SAMPLE_DISPLAY_DIRECTION element is the preferred orientation of samples within a line for viewing on a display device. The default is right, meaning samples are viewed from left to right on the display. See also line_display_direction. NAME = SAMPLING_PARAMETER_INTERVAL DESCRIPTION = The sampling_parameter_interval element identifies the spacing of points at which data are sampled and at which a value for an instrument or dataset parameter is available. See also sampling_parameter_unit. NAME = SAMPLING_PARAMETER_UNIT DESCRIPTION = The sampling_parameter_unit element specifies the unit of measure of associated data sampling parameters. For IRAS Tempel 1 images, the unit is degree/pixel. See also sampling_parameter_interval. NAME = SOLAR_DISTANCE UNIT_ID = AU DESCRIPTION = The solar_distance element provides the distance from the center of the sun to the center of a target body. NAME = SOLAR_ELONGATION UNIT_ID = DEGREE DESCRIPTION = " The angle between the line of sight of observation and the direction of the Sun. For IRAS, solar_elongation is the line of sight of observation is the boresight of the telescope as measured by the satellite sun sensor. NAME = SPACECRAFT_CLOCK_START_COUNT UNIT_ID = SECOND DESCRIPTION = The spacecraft_clock_start_count element provides the value of the spacecraft clock at the beginning of a time period of interest. For an IRAS Tempel 1 Additional Observation, spacecraft_clock_start_count is the value of the spacecraft clock at the start of the entire observation (see also observation_duration). For an IRAS Tempel 1 Survey Scan, spacecraft_clock_start_count is the value of spacecraft clock at the start of the earliest scan in the set of scans used to make an image mosaic. NAME = SPACECRAFT_CLOCK_STOP_COUNT UNIT_ID = SECOND DESCRIPTION = The spacecraft_clock_stop_count element provides the value of the spacecraft clock at the end of a time period of interest. For an IRAS Tempel 1 Additional Observation, spacecraft_clock_start_count is the value of the spacecraft clock at the end of the entire observation (see also observation_duration). For an IRAS Tempel 1 Survey Scan, spacecraft_clock_start_count is the value of spacecraft clock at the end of the latest scan in the set of scans used to make an image mosaic. NAME = START_TIME DESCRIPTION = The start_time element provides the UTC date and time of the beginning of observation in UTC system format. The IRAS Tempel 1 data, start_time is the spacecraft_clock_start_count converted to UTC date and time. Formation rule: YYYY-MM-DDThh:mm:ss[.fff] NAME = STOP_TIME DESCRIPTION = The stop_time element provides the UTC date and time of the end of observation in UTC system format. The IRAS Tempel 1 data, stop_time is the spacecraft_clock_stop_count converted to UTC date and time. Formation rule: YYYY-MM-DDThh:mm:ss[.fff] NAME = TARGET_CENTER_DISTANCE UNIT_ID = AU DESCRIPTION = The target_center_distance element provides the distance between an instrument and the center of mass of the target. NAME = WAVELENGTH DESCRIPTION = The wavelength element identifies the mean wavelength to which an instrument detector/filter combination is sensitive. For IRAS Tempel 1 data, wavelength have values of 12, 25, 60, 100 micron.