PDS_VERSION_ID = PDS3 LABEL_REVISION_NOTE = "2003-05-05, PDS-SBN, Created." OBJECT = DATA_SET DATA_SET_ID = "IRAS-C-FPA-5-SSIMAGE-TEMPEL1-DI-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = " IRAS SURVEY SCANS OF 9P/TEMPEL1 REPROCESSED FOR DI V1.0" DATA_SET_TERSE_DESC = " Reprocessed IRAS Survey Scans of comet 9P/Tempel 1 to support the NASA Deep Impact Mission." DATA_SET_COLLECTION_MEMBER_FLG = "N" START_TIME = 1983-07-14 STOP_TIME = 1983-09-29 SPACECRAFT_CLOCK_START_COUNT = 79843985 SPACECRAFT_CLOCK_STOP_COUNT = 86522805 DATA_OBJECT_TYPE = IMAGE DATA_SET_RELEASE_DATE = 2003-05-29 /* Preliminary Review Date */ PRODUCER_FULL_NAME = "STEPHANIE A. MCLAUGHLIN" SOFTWARE_FLAG = "N" DETAILED_CATALOG_FLAG = "N" PROCESSING_START_TIME = "N/A" PROCESSING_STOP_TIME = "N/A" DATA_SET_DESC = " Data Set Overview ================= IRAS spent the majority of its observing time in the survey mode that systematically mapped the sky with a series of overlapping and confirming scans (WHEELOCKETAL1994). This reduncancy can be used to produce an image of fainter limiting magnitudes to improve the spatial resolution in the scanned fields. IRAS Survey Scans (SS) were acquired by the IR Focal Plane Array, a multi-wavelength detector with spectral bands centered nominally at 12, 25, 60, and 100 microns (BEICHMANETAL1988). To support analysis of the dust coma of comet 9P/Tempel 1 for the Deep Impact Mission, Russell Walker identitied IRAS SS which happened to contain the comet. Russell Walker used a computer algorithm similar to the IPAC HIRES program to construct radiance and noise maps from sets of overlapping SS. The radiance maps are surface brightness images. The noise maps are images the standard deviation of the radiance in a pixel as a result of averaging overlapping detector samples. All SS radiance and noise images (maps) are 150 x 75 pixels. The square, 24-arcsecond pixels yield an image size of about 1.0 x 0.5 degrees. The images were constructed by referencing the samples to the orbital position of the comet at the time of the sample. Thus, the comet is always located in the center of the image. Since a map was constructed from several SS, it is a time-averaged image of the emission history of the comet. Parameters ========== This data set contains radiance and noise maps reconstructed from Survey Scans acquired during satellite observation plans (mean SOP, that is, OBSERVATION_ID) 339, 368, 389, 421, and 493 at 12, 25, 60, and 100 microns. All iamges are post-perihelion. Perihelion occurred at UTC 1983-07-09T19:08:11 (Julian date 2445525.2973512). The naming convention for Survey images is sSOP_BANDum_ITERATION_TYPE.fit where SOP is the satellite observation plan number, Band is the band wavelength in microns, ITERATION is the processing iteration number, and TYPE identifies radiance or noise map. Radiance and noise map images are in units of in-band radiance, Watts/cm^2/steradian. Processing ========== Russell Walker used a computer algorithm based on the Maximum Correlation Method (AUMANNETAL1990). It closely parallels the HIRES program at IPAC (MELNYKRICE1991) but departs from the IPAC scheme in the Comet Image Processor (DOCUMENT/EXP_SUPP_SURVEY.PDF) where the coordinates of each data sample are transformed to a moving Sun-referenced coordinate system with the comet at the origin. The algorithm iteratively builds radiance and noise maps, saving statistics relating to pixel noise and convergence for each iteration. A typical image will converge after 15 to 40 iterations. Radiance and noise maps from the first iteration and the final, best iteration for each OBSERVATION_ID and band combination are included in this data set. Data ==== The data are in the form of FITS files with attached FITS headers and detached PDS labels. Data files contain one radiance image or one noise map per file. Ancillary Data ============== Refer to the CALIB/SURVEY and CALIB/FILTER subdirectory for details. Coordinate System ================= The coordinate system is solar elongation and inclination of the observation which is the natural coordinate system for IRAS. Solar elongation is the angle between the line of site and the Sun. Inclination is the azimuth angle about the Earth-Sun axis (that is, the angle between the ecliptic plane and the plane containing the Earth, Sun, and observing direction). Inclination is 0 degrees when IRAS looks at the ecliptic plane in the direction opposite to the motion of the Earth. Inclination increases clockwise, from 0 to 360 degrees, around the Earth-Sun axis when facing the Sun. Therefore, the inclination is 90 degrees when IRAS is over north ecliptic pole and 180 degrees when looking at the ecliptic plane in the direction of the motion of the Earth The inclination angle increases opposite the direction of IRAS's polar orbit about Earth. Media/Format ============ This data set is released as a CDROM set. " CONFIDENCE_LEVEL_NOTE = " Confidence Level Overview ========================= While the first iteration of radiance and noise maps are provided for each reconstructed SS image, the final iteration should be used for analysis. Review ====== The data will undergo a first-look review at the May 2003 PDS-SBN Asteroid Peer Review. " END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = "9P/TEMPEL 1 (1867 G1)" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = "IRAS" INSTRUMENT_ID = "FPA" END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "AUMANNETAL1990" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "BEICHMANETAL1988"" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "MELNYKRICE1991" END_OBJECT = DATA_SET_REFERENCE_INFORMATION OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "WHEELOCKETAL1994" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END