PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 2014-01-18 NOTE = "Description of the contents of the calib dir. History: 2014-01 BTCarcich Added genesis of the calibration file. " END_OBJECT = TEXT END ######################################################################## ### N.B. The full description of the calibration procedure is in the ### the SOC Instrument Interface Control Document (ICD) in the ### /DOCUMENT/ directory of this archive ######################################################################## Genesis of the calibration data (from the ICD): In a temperature controlled environment, the electronics from the end of the PVDF to the DN in the raw data were calibrated, at each of 4 calibration box temperatures and for each of the 14 channels. This was done by injecting 19 (actually 21; see the ICD) fixed-amplitude charge pulses 100 times into a channel and recording the DN value each time. From those recorded values, the average DN (DNavg) and its standard deviation (SIG) at each charge pulse amplitude, box temperature and channel were calculated. Then, for each box temperature and channel, a 9th order polynomial fit of Q(DNavg) was derived. Finally, these 3 sets of values (the polynomial coefficients, DNavg, and SIG) were stored in a matrix. This matrix contains all information required to calculate the charge equivalent to a DN as a function of box temperature and channel (detector), as well as the uncertainty in that calculated charge value. That matrix has been broken out into the forty-two PDS ASCII TABLEs in this directory. [calib] Directory containing 42 ASCII TABLEs containing information | for calibration of data from SDC observations. | +-- SDC_CAL_MATRIX_COEF_CHnn.TAB 14 coefficient table files (Note 1) | +-- SDC_CAL_MATRIX_MEAN_CHnn.TAB 14 mean DN table files (Note 1) | +-- SDC_CAL_MATRIX_STDV_CHnn.TAB 14 DN standard deviation files (Note 1) | +-- calinfo.txt This file Note 1: the nn in each filename above will be a two-digit, zero-padded number from 01 to 14 in the actual filenames, indicating to which of the fourteen SDC channels the file is to be applied. Note 2: Channel 11 is non-functional due to a broken capacitor connection that occurred before launch; that channel generates spurious events that should be ignored. Refer to the descriptions in the ASCII tables for more detail about what is in each table; refer to the SOC Instrument ICD for a description of how to use the data in these tables to calibrate SDC data (convert the DN of an impact event reading to charge and to mass). N.B. The SDC calibration matrix has been converted, from the four- dimensional array in the Primary Data Unit of a FITS file, to these 42 ASCII tables to make the archive product compliant with PDS standards. The number of digits displayed in the table is sufficient to reproduce the data in the original FITS files, bit for bit. The rows in the tables, indicating the order of each coefficient in the coefficient tables, or indicating a known input charge used in a 100-sample test during ground calibration for the mean DN and DN standard deviation tables, correspond to NAXIS4, the slowest-moving axis in the original FITS file The three types of tables correspond to NAXIS3 in the original FITS file. The fourteen tables within each type of table correspond to NAXIS2 in the original FITS file. The columns in the table, indicating at which temperature each column is valid, correspond to NAXIS1, the fastest moving-axis in the original FITS file. See the EXTRAS/ directory, if present, for more information, including the calibration matrix in its original FITS form as used by the New Horizons data processing and calibration pipeline, and a script to convert these forty-two tables back into the single-file FITS form.