CCSD3ZF0000100000001NJPL3IF0PDSX00000001 PDS_VERSION_ID = PDS3 /* File Format and Length */ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 137 FILE_RECORDS = 5749 DATA_SET_ID = "IRAS-D-6-SDR-SHF-V1.0" DATA_SET_NAME = "IRAS SCAN HISTORY FILE V1.0" /* Record Pointer to Major Object */ ^TABLE = "SCAN.TAB" /* Description of Object in File */ OBJECT = TABLE ROWS = 5749 ROW_BYTES = 137 INTERCHANGE_FORMAT = ASCII COLUMNS = 14 DESCRIPTION = "The IRAS Scan History File describes the pointing geometry and length of each survey-mode scan (by SOP OBS) over the entire mission. General information about the Infrared Astronomical Satellite (IRAS) and its mission may be found in Beichman et al. (1988) and Neugebauer et al. (1984)." OBJECT = COLUMN NAME = OBSERVATION_ID DESCRIPTION = "The observation sequence number is given in the form SSS.OO, where SSS denotes the IRAS Satellite Observation Plan (SOP) and OO denotes the observation number within a SOP. The SOP is the basic time interval of operations and data acquisition during the IRAS mission, corresponding to the time between station passes, varying between seven and eight orbits (10 to 14 hours). There were two SOP's per day or 600 SOP's in the entire mission (Beichman, et al. 1988). Missing SOPs correspond to non-survey mode observations and include SOPs 53,54,55,56,58,200,258,259, 260,261,262,263,264,442,594,595,596,597, and 598. Each SOP consisted of 76 or fewer commands (OBS) for survey observations, pointed observations, calibration measurements, and other measurements, each of which was designated by an OBS number. Missing OBS numbers correspond to non-survey mode observations or measurements. Julian date of observation can be estimated from the SOP number by the formula JD=2445360+SSS/2." DATA_TYPE = REAL START_BYTE = 1 BYTES = 6 FORMAT = "F6.2" END_OBJECT OBJECT = COLUMN NAME = NATIVE_START_TIME UNIT = SECOND DESCRIPTION = "The elapsed time in seconds since 0 hours UT (Coordinated), 1 January 1981 (Beichman et al. 1988). Times are uncertain to about 2 seconds, based on information that during the mission differences of this magnitude were discovered, but not corrected." DATA_TYPE = REAL START_BYTE = 8 BYTES = 10 FORMAT = "F10.1" END_OBJECT OBJECT = COLUMN NAME = NATIVE_STOP_TIME UNIT = SECOND DESCRIPTION = "The elapsed time in seconds since 0 hours UT (Coordinated), 1 January 1981 (Beichman et al. 1988). Times are uncertain to about 2 seconds, based on information that during the mission differences of this magnitude were discovered, but not corrected." DATA_TYPE = REAL START_BYTE = 19 BYTES = 10 FORMAT = "F10.1" END_OBJECT OBJECT = COLUMN NAME = ORBIT_NUMBER DESCRIPTION = "Orbit number" DATA_TYPE = INTEGER START_BYTE = 30 BYTES = 4 FORMAT = I4 END_OBJECT OBJECT = COLUMN NAME = SOLAR_ELONGATION UNIT = DEGREE DESCRIPTION = "The angle between the line of sight of observation and the direction of the Sun. For IRAS: the line of sight of observation is the boresight of the telescope as measured by the satellite sun sensor." DATA_TYPE = REAL START_BYTE = 35 BYTES = 10 FORMAT = "F10.6" END_OBJECT OBJECT = COLUMN NAME = SOLAR_ELONGATION_SIGMA UNIT = DEGREE DESCRIPTION = "The standard deviation of the solar elongation determined from variations in values from the spacecraft Sun-sensor." DATA_TYPE = REAL START_BYTE = 46 BYTES = 10 FORMAT = "E10.4" END_OBJECT OBJECT = COLUMN NAME = IRAS_CLOCK_ANGLE_START UNIT = DEGREE DESCRIPTION = "At the beginning of a scan, the satellite viewing angle projected onto the plane perpendicular to the Sun-line, measured from ecliptic North, clock-wise as viewed from the Sun. This is the same direction as the IRAS orbital motion. Scans whose clock angles are primarily between 0 and 180 degrees are descending scans, and ascending scans are those with clock angles between 180 and 360 degrees." DATA_TYPE = REAL START_BYTE = 57 BYTES = 10 FORMAT = "F10.6" END_OBJECT OBJECT = COLUMN NAME = IRAS_CLOCK_ANGLE_RANGE UNIT = DEGREE DESCRIPTION = "The change in the clock angle during the elapsed time of the scan." DATA_TYPE = REAL START_BYTE = 68 BYTES = 10 FORMAT = "F10.6" END_OBJECT OBJECT = COLUMN NAME = IRAS_CLOCK_ANGLE_RATE UNIT = "DEGREES PER SECOND" DESCRIPTION = "The average time rate of change of the clock angle during a scan, determined from signals from the z-gyro of the satellite (z being the direction of the Sun)." DATA_TYPE = REAL START_BYTE = 79 BYTES = 11 FORMAT = "E11.4" END_OBJECT OBJECT = COLUMN NAME = IRAS_CLOCK_ANGLE_RATE_SIGMA UNIT = "DEGREES PER SECOND" DESCRIPTION = "The standard deviation of the scan rate determined deom variations in values determined from signals from the spacecraft z-gyro." DATA_TYPE = REAL START_BYTE = 91 BYTES = 10 FORMAT = "E10.4" END_OBJECT OBJECT = COLUMN NAME = START_ECLIPTIC_LATITUDE UNIT = DEGREE DESCRIPTION = "The geocentric ecliptic latitude (B1950) of observation at the start of a scan." DATA_TYPE = REAL START_BYTE = 102 BYTES = 10 FORMAT = "E10.6" END_OBJECT OBJECT = COLUMN NAME = STOP_ECLIPTIC_LATITUDE UNIT = DEGREE DESCRIPTION = "The geocentric ecliptic latitude (B1950) of observation at the end of a scan." DATA_TYPE = REAL START_BYTE = 113 BYTES = 10 FORMAT = "E10.6" END_OBJECT OBJECT = COLUMN NAME = SOLAR_LONGITUDE UNIT = DEGREE DESCRIPTION = "The geocentric ecliptic longitude (B1950) of the Sun at the start of a scan." DATA_TYPE = REAL START_BYTE = 124 BYTES = 10 FORMAT = "E10.6" END_OBJECT OBJECT = COLUMN NAME = IRAS_HCON DESCRIPTION = "HCON is hours-confirmation. In order that the reliability of the IRAS observations could be maximized, the satellite scanning strategy was designed so that a piece of sky would be reobserved on timescales of hours (generally one orbit of 103 minute). Three hours- confirmed surveys, designated HCONS 1, 2, and 3, respectively, of the sky were made by IRAS over the course of its mission. HCON 1 and 2 observations were interleaved on timescales of weeks, while HCON 3 consists of all scans after SOP 426, inclusive. See Beichman et al. (1988) for further information." DATA_TYPE = INTEGER START_BYTE = 135 BYTES = 1 FORMAT = I1 END_OBJECT END_OBJECT END