PDS_VERSION_ID = PDS3 /* File Characteristics */ RECORD_TYPE = FIXED_LENGTH RECORD_BYTES = 138 FILE_RECORDS = 5749 /* Data Object Pointers */ ^TABLE = "scan.tab" /* Identification Keywords */ DATA_SET_ID = "IRAS-6-SDR-SATELLITE-STATUS-V1.0" PRODUCT_NAME = "IRAS Scan History File" PRODUCT_ID = "SAT-SCAN-199703" INSTRUMENT_HOST_NAME = "INFRARED ASTRONOMICAL SATELLITE" INSTRUMENT_NAME = "N/A" TARGET_NAME = "N/A" START_TIME = 1983-02-08 STOP_TIME = 1983-11-21 PRODUCT_CREATION_TIME = 1997-03-24 /* Peer Review Date */ RECORD_FORMAT = "(f6.2,2(1x,f10.1),1x,i4,1x,f10.6,1x,e10.4, 2(1x,f10.6),1x,e11.4,1x,e10.4,3(1x,e10.6),1x,i1)" /* Data Object Descriptions */ OBJECT = TABLE ROWS = 5749 ROW_BYTES = 138 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 COLUMN_NUMBER = 1 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 = ASCII_REAL START_BYTE = 1 BYTES = 6 FORMAT = "F6.2" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 2 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 = ASCII_REAL START_BYTE = 8 BYTES = 10 FORMAT = "F10.1" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 3 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 = ASCII_REAL START_BYTE = 19 BYTES = 10 FORMAT = "F10.1" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 4 NAME = "ORBIT NUMBER" DESCRIPTION = "Orbit number" DATA_TYPE = ASCII_INTEGER START_BYTE = 30 BYTES = 4 FORMAT = I4 END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 5 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 = ASCII_REAL START_BYTE = 35 BYTES = 10 FORMAT = "F10.6" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 6 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 = ASCII_REAL START_BYTE = 46 BYTES = 10 FORMAT = "E10.4" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 7 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 = ASCII_REAL START_BYTE = 57 BYTES = 10 FORMAT = "F10.6" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 8 NAME = "IRAS CLOCK ANGLE RANGE" UNIT = DEGREE DESCRIPTION = "The change in the clock angle during the elapsed time of the scan." DATA_TYPE = ASCII_REAL START_BYTE = 68 BYTES = 10 FORMAT = "F10.6" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 9 NAME = "IRAS CLOCK ANGLE RATE" UNIT = "DEGREE 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 = ASCII_REAL START_BYTE = 79 BYTES = 11 FORMAT = "E11.4" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 10 NAME = "IRAS CLOCK ANGLE RATE SIGMA" UNIT = "DEGREE 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 = ASCII_REAL START_BYTE = 91 BYTES = 10 FORMAT = "E10.4" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 11 NAME = "START ECLIPTIC LATITUDE" UNIT = DEGREE DESCRIPTION = "The geocentric ecliptic latitude (B1950) of observation at the start of a scan." DATA_TYPE = ASCII_REAL START_BYTE = 102 BYTES = 10 FORMAT = "F10.6" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 12 NAME = "STOP ECLIPTIC LATITUDE" UNIT = DEGREE DESCRIPTION = "The geocentric ecliptic latitude (B1950) of observation at the end of a scan." DATA_TYPE = ASCII_REAL START_BYTE = 113 BYTES = 10 FORMAT = "F10.6" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 13 NAME = "SOLAR LONGITUDE" UNIT = DEGREE DESCRIPTION = "The geocentric ecliptic longitude (B1950) of the Sun at the start of a scan." DATA_TYPE = ASCII_REAL START_BYTE = 124 BYTES = 10 FORMAT = "F10.6" END_OBJECT = COLUMN OBJECT = COLUMN COLUMN_NUMBER = 14 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 = ASCII_INTEGER START_BYTE = 135 BYTES = 1 FORMAT = I1 END_OBJECT = COLUMN END_OBJECT = TABLE END