PDS_VERSION_ID = PDS3 RECORD_TYPE = "FIXED_LENGTH" RECORD_BYTES = 80 OBJECT = TEXT PUBLICATION_DATE = 2006-09-29 NOTE = "Description of the CALIB directory" END_OBJECT = TEXT END CALIB Directory Contents This file describes the contents of the calibration directory. The Deep Impact calibration pipeline used the files in this directory to reduce raw data. The files were the result of the analysis of ground-based, thermal- vacuum and in-flight data for the instrument. For more information about these files, the analysis, and the calibration pipeline, see the 'Deep Impact Instrument Calibration' paper included on the Deep Impact documentation volume, DIDOC_0001. The calibration data were provided as FITS image files or ASCII tables. The following file naming convention was used: CCCCC/IIIIII-YYMMDD-V-M-FFF.{FIT,TAB} | | | | | | | | | | | Optional filter number, temperature, or | | | | | place holder value such as '999' | | | | | | | | | Instrument/Image mode (1 through 9) or a place | | | | value of '0' to indicate all modes | | | | | | | File version (1, 2, etc.) | | | | | Date from which file is valid. This is not the date the file | | was created. A value of '020601' indicates the file was | | created from thermal-vacuum data. A value of '000101' was | | used a place holder. It provides no useful information | | but was required to keep the pipeline running. | | | Instrument designation (e.g. ITSVIS for ITS) | Directory for the type of calibration file (e.g. FLAT for flat fields) Here is an example of a complete file name, FLAT/ITSVIS_020601_2_1_1.FIT: - FLAT Flat field - ITSVIS ITS Instrument - 020601 This flat was created from thermal-vacuum data and can can be applied to images on or after 2005-01-12 (launch) - 2 Version 2 of the file for the specified effective date - 1 Instrument (image) mode 1 - 1 Place holder (ITS did not have filters) - .FIT FITS file Calibration files are grouped into subdirectories by type: ABSCALVS -------- This subdirectory contains one table for the absolute calibration constants for each instrument (image) mode. The first column specifies the constant for converting raw data numbers to units of radiance, W/(M**2 SR UM). The second column specifies the constant for converting from units of radiance to units of reflectance (i.e., I-over-F or the observed radiance over the input solar radiance). ADCLUT ------ This subdirectory contains a lookup table for the correcting for uneven bit weighting caused by the analog-to-digital conversion. The single table applies to all instrument modes. As of this archive, the corrections had not been derived. Therefore, the input pixel values are the same as the output values to prevent the automated calibration pipeline from changing the data. Although this correction was omitted during the calibration of the navigation images, the tables are provided for reference. BADPIX ------ This subdirectory contains maps that identify bad pixels for each instrument mode. Bad pixels are set to 1. Good pixels are set to 0. Overscan columns and rows at the edges of the CCD array are set flagged as good (0). There is one horizontal row of warm pixels near the top and bottom of each map. These rows are flagged as bad (1). BIAS ---- This subdirectory contains a bias correction map for each instrument mode. These maps were not used to calibration navigation images because pre-calculated correction values (see the navigation images report on the Deep Impact documentation volume). However, these maps are provided for reference. DRKMODEL -------- This subdirectory contains maps for modeling the dark signal for each instrument mode. FLAT ---- This subdirectory contains flat fields for each instrument mode. GAIN ---- This subdirectory contains a quadrant gain correction map for each instrument mode. The values were normalized to the gain correction at launch. All pixels within a given quadrant have the same value. Although gains were included in the flats, these maps are provided for reference. PSF --- This subdirectory contains a dummy point-spread function used by the calibration pipeline when one is not available. It is a centered delta function to prevent changes to the data. XTALK ----- This subdirectory contains a table that specify the amount of gain from electronic cross talk that occurs between all possible combinations of the four quadrants of the CCD. Although this correction was omitted during the calibration of the navigation images, this table was provided for reference.