PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM LABEL_REVISION_NOTE = " 2004-08-25 S.McLaughlin Created; 2005-02-07 S.McLaughlin Resolved liens from Oct 2004 thermal-vac review; 2005-05-22 DI:McLaughlin Resolved liens from Oct 2006 peer review; 2006-12-05 DI:McLaughlin Resolved liens from Nov 2006 peer review; 2007-05-30 DI:S.McLaughlin Added RECORD_TYPE, reference id KLAASENETAL2005; " OBJECT = INSTRUMENT INSTRUMENT_HOST_ID = "DII" INSTRUMENT_ID = "ITS" OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "DEEP IMPACT IMPACTOR TARGETING SENSOR - VISIBLE CCD" INSTRUMENT_TYPE = "CCD CAMERA" INSTRUMENT_DESC = " Instrument Overview =================== The Impactor Targeting Sensor (ITS) consisted of an f/17.5 Cassegrain telescope feeding directly onto a CCD for direct, optical imaging. It was an exact clone of the Medium Resolution Instrument (MRI) and its visual CCD camera except that the filter wheel had been deleted. In all other respects it was identical. The ITS telescope was a classical Cassegrain design with the following parameters: Primary aperture : 12.0 cm diameter, round Primary focal ratio : 3.75 Secondary Obscuration : 6.6 cm diameter, round Secondary magnification : 4.75x (net Cassegrain focal length 210 cm) Back focal distance : 30.0 cm The detector was a 1024 x 1024 split-frame, frame-transfer CCD with 21-micron-square pixels. The electronics allowed readout of centered sub-frames in multiples of 2: 64x64, 128x128, and so on, with or without rows of overscan. Transfer time, to move the two halves of the image from the exposing area to the two shielded areas was about 5.2 milliseconds. There were readout amplifiers in each of the four quadrants. Readout time for a full frame was 1.8 seconds. Net pixel scale was 10 microradians/pixel (2 arcseconds/pixel). The surface scale was 0.2 meters/pixel at 20 kilometers. Images were transmitted to the flyby spacecraft for re-transmission to Earth. The ITS instrument was mounted behind the main deck of the impactor spacecraft and looked through a rectangular cutout on one edge of the copper cratering mass at the front of the impactor. For a detailed discussion of the instrument, see Hampton, et al. (2005) [HAMPTONETAL2005]. This instrument overview was provided by Dr. Michael A'Hearn, the principal investigator for the Deep Impact mission. Instrument Calibration ====================== The ITS instrument was calibrated by using in-flight data as well as pre-launch data taken during a thermal-vacuum test (TV3) performed in January and February 2003. The calibration of the ITS instrument was discussed in the 'Deep Impact Instrument Calibration' paper by Klaasen, et al. (2006) [KLAASENETAL2006]. There is a 1/3-pixel, horizontal gap for a clocking phase between the upper and lower halves of the CCD. It was inserted by the manufacturer to facilitate the simultaneous upward and downward reading of the upper and lower quadrants. The gap causes a 10 percent reduction in the sensitivity of the two central rows (i.e., one row immediately above the gap and one below it). Flight Performance ================== The ITS instrument generally performed as expected during flight. " END_OBJECT = INSTRUMENT_INFORMATION OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "HAMPTONETAL2005" END_OBJECT = INSTRUMENT_REFERENCE_INFO OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "KLAASENETAL2005" END_OBJECT = INSTRUMENT_REFERENCE_INFO OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "KLAASENETAL2006" END_OBJECT = INSTRUMENT_REFERENCE_INFO END_OBJECT = INSTRUMENT END