PDS_VERSION_ID        = PDS3

RECORD_TYPE           = STREAM



OBJECT                = TEXT

   PUBLICATION_DATE    = 2006-03-28

   NOTE                = "Description of contents of CDR directory"

END_OBJECT            = TEXT

END



The CDR directory is present in the EDR archive volume. It contains CRISM 

VNIR and IR "Calibration Data Records" or "CDRs". CRISM uses a collection of 

CDRs to convert data from raw DNs to units of radiance or I/F. CDRs are 

created in two ways:



(a) One type of calibration file, for example the wavelength calibration, is 

either invariant or expected to change only infrequently. These files are 

stored in directories named using a 2-letter acronym for the contents of the 

file.



(b) The other type of calibration file is a snapshot of some attribute of 

the instrument that is time-variable, for example the thermal background 

measured by the IR detector. These files are stored in directories named 

YYYY_DOY, each one of which contains subdirectories containing distinct 

types of calibration files.



There are two types of calibration files. CODMAC level 4 CDRs (CDR4s) are in 

image format, and CODMAC level 6 CDRs (CDR6s) are text files in ASCII 

format. Both types have a file name that encodes the time at which they are 

applicable, and the configuration of the data used to derive them (detector, 

frame rate, binning, wavelength filter, exposure time parameter, etc.).



YYYY_DOY/BI directory:

This directory contains CDR4s representing measurements of the response of 

each detector to zero signal, i.e., the detector bias. These are measured as 

dark frames for the VNIR detector. For the IR detector, these are the zero 

exposure-time intercept of a fit of dark measurements taken at several 

exposure times. For each detector there are separate files for each frame 

rate, wavelength filter, and binning state, time-stamped for their mean time 

of acquisition. 



YYYY_DOY/BK directory:

This directory contains CDR4s representing thermal background measured by 

the IR detector. These are measured as dark frames. There are separate files 

for each frame rate, exposure time, and binning state, time-stamped for 

their mean time of acquisition. 



YYYY_DOY/BP directory:

This directory contains CDR4s representing bad pixels. There are separate 

files for each frame rate, exposure time, wavelength filter, and binning 

state, time-stamped for their mean time of acquisition. 



YYYY_DOY/SP directory:

This directory contains CDR4s representing sphere output in DN/ms at the 

sphere's closed-loop setpoint. There are separate files for each sphere 

bulb. For the VNIR all data are taken at 1 Hz, but there are versions for 

each binning state. For the IR there are separate versions for each frame 

rate, wavelength filter, and binning state. Both the VNIR and IR files are 

time-stamped for their mean time of acquisition. 



YYYY_DOY/ST directory:

This directory contains a table of CRISM low-rate telemetry in raw counts, 

from the beginning of a UTC calendar day to its end. This is used in 

preference to the telemetry attached to each image for correction of thermal 

effects, because of uncorrectable artifacts in the raw values of critical 

temperature measurements in the image headers.



YYYY_DOY/UB directory:

This directory contains CDR4s representing pixel-by-pixel uncertainties in 

VNIR bias or IR background images. There are separate files for each frame 

rate, exposure time, wavelength filter, and binning state, time-stamped for 

their mean time of acquisition. This product is not a part of the nominal 

data processing pipeline and instead is used to monitor detector health.



YYYY_DOY/ATF directory:

This directory contains a table of EDRs containing scene data and the 

corresponding EDRs containing time-dependent calibration measurements needed 

to calibrate the scene EDRs. It is used to process calibration EDRs to CDRs, 

and scene EDRs to TRDRs. If there is a discrepancy between the actual EDRs 

used for calibration and the predicted EDRs (in the BTF directory), the 

TRDRs resulting from scene EDRs are quality-flagged.



YYYY_DOY/BTF directory:

This directory contains a predicted table of EDRs containing scene data and 

the corresponding EDRs containing time-dependent calibration measurements. 

It is constructed from uplinked commands.



AS directory:

This CDR6 gives the maximum expected 14-bit scene or sphere 14-bit DN level 

(units from the detector, after correction for the pixel processing table 

and subtraction of bias) for core observation types to be made by CRISM. 

There are 5 core observation types defined by combinations of frame rate, 

exposure time, and scene: 1 Hz observation, exposure parameter 27, observing 

the internal integrating sphere; 3.75 Hz, exposure parameter 301, observing 

a nominally non-ice region of Mars; 3.75 Hz, exposure parameter 147, 

observing a potentially ice-containing region; 15 Hz, exposure parameter 

425, observing any region; and 30 Hz, exposure parameter 425, observing any 

region. The values given here are used with bias images in the YYYY_DOY/BI 

directories to generate masks of probably bad pixels (in the YYYY_DOY/BI 

directories).



BS directory:

This CDR6 gives the amplitude of the bias step correction for each detector 

as a function of frame rate and quadrant. The bias step is a step function 

in detector bias that occurs at a row number (band) correlated with exposure 

time parameter.



BW directory:

This CDR6 gives the parameters to calculate the spectral profile for each 

wavelength bin averaged over IR columns 270-369 or VNIR columns 260-359. 

This represents the "sweet spot" of each detector at which spectral smile 

and keystone are minimum, and is the preferred detector location for 

extraction of overlapping data for analysis of emission phase functions.



CM directory:

This CDR4 gives the along-slit angle measured from slit center for each 

detector. It is similar to the SPICE Instrument Kernel. There is a different 

version for each detector, wavelength filter, and binning state.



DB directory:

This CDR6 gives the correction to detector bias for changes in detector 

temperature since the last bias measurement, as a function of frame rate and 

quadrant.



DM directory:

This CDR4 is a mask of detector dark columns, scattered light columns, and 

scene columns for each detector. There is a different version for each 

wavelength filter and binning state.



EB directory:

This CDR6 gives the correction to detector bias for differences in focal 

plane electronics temperature since the last bias measurement, as a function 

of frame rate and quadrant.



GH directory:

This CDR6 gives the scaling factors needed for each frame rate to calculate 

and subtract the inter-quadrant electronics ghost in each detector, using 

bias-corrected signal.



HD directory:

This CDR6 gives the coefficients for correcting raw housekeeping for 

perturbations due to changes in lamp or cooler state and frame rate. There 

is one file for both detectors.



HK directory:

This CDR6 gives the coefficients to convert housekeeping parameters from raw 

counts to physical units.



HV directory:

This CDR6 gives the coefficients to correct housekeeping voltages for 

perturbations due to changes in current.



LC directory:

This CDR6 gives the coefficients to correct bias-subtracted DN from each 

detector at each frame rate for non-linearity in detector response.



LI directory:

This CDR6 gives 8 to 12 bit lookup tables (inverse of 12 to 8). These are 

used to restore 8-bit to 12-bit DN values.



LK directory:

This CDR6 gives 12 to 8 bit lookup tables loaded in the CRISM instrument.



LL directory:

This CDR4 contains matrices to remove estimated leaked higher order light in 

the IR detector, by scaling shorter-wavelength signal and subtracting it 

from longer-wavelength signal.



NU directory:

This CDR4 is a time-tagged, row-normalized measurement of detector 

nonuniformity. There is one version for each binning state, wavelength 

filter, and frame rate. It is only created for the VNIR detector.



PP directory:

This CDR6 contains the gain and offset to use for each row to convert 12-bit 

DNs to the native 14-bit DNs produced by each detector, and the 12 to 8 bit 

lookup tables used for each detector row (band) when lossy compression is 

employed.



PS directory:

This CDR4 is used for nearest neighbor spectral resampling. It gives the 

number of detector rows (bands) by which to shift each column (sample) of an 

image to minimize the effects of spectral smile. The effect of the pixel 

shift is to restore the wavelength at a detector element to within one-half 

detector element of the wavelength in the central columns of the detector. 

(The wavelength and spectral bandwidth in the central columns are given in 

the SW and BW directories respectively.) There is a different version for 

each detector, wavelength filter, and binning.



RA directory:

This CDR4 contains the ratio of focal plane lamp illumination to an external 

flat field, normalized on a row-by-row basis. This is a contingency and not 

part of the normal calibration pipeline, so its creation is TBD. There is a 

different version for each detector, wavelength filter, and binning.



RF directory:

This CDR4 contains a nearest-neighbor resampled solar flux image. It is 

related to the "native" solar flux images in the SF directory by the pixel-

shifting given in the PS directory. There is a different version for each 

detector, wavelength filter, and binning.



RW directory:

This CDR4 contains a nearest-neighbor resampled wavelength image. It is 

related to the "native" wavelength images in the WA directory by the pixel-

shifting given in the PS directory. There is a different version for each 

detector, wavelength filter, and binning.



SB directory:

This CDR4 contains the spectral bandpass width for each detector element. 

There is a different version for each detector, wavelength filter, and 

binning.



SF directory:

This CDR4 contains solar flux at 1 AU for each detector element. There is a 

different version for each detector, wavelength filter, and binning. It is 

used together with the solar distance given in an EDR or TRDR label to 

calculate I/F.



SH directory:

This 2-layer CDR4 is used to correct flight measurements of the onboard 

integrating sphere for effects of shutter position irreproducibility. Layer 

0 is a corrected sphere image from ground radiometric calibration in units 

of 14-bit DN.  Layer 1 is a shutter mirror non-repeatability correction 

image, a multiplicative correction that gets scaled by the ratio of layer 0 

to the measured flight sphere image. There is a different version for each 

detector, wavelength filter, and binning.



SL directory:

This CDR6 gives the 14-bit DN at which each detector is saturated, as a 

function of quadrant and frame rate.



SS directory:

This 3-layer CDR4 gives sphere spectral radiance at the closed-loop set 

point for each sphere bulb, as pixel by pixel coefficients to a 2nd order 

polynomial function of sphere temperature. There is a different version for 

each detector, wavelength filter, and binning.



SW directory:

This CDR6 gives the center wavelength for each wavelength bin averaged over 

IR columns 270-369 or VNIR columns 260-359. This represents the "sweet spot" 

of each detector at which spectral smile and keystone are minimum, and is 

the preferred detector location for extraction of overlapping data for 

analysis of emission phase functions.



TD directory:

This CDR4 gives temperature dependence of detector responsivity, as pixel by 

pixel coefficients to a 2nd order polynomial function of detector 

temperature. There is a different version for each detector, wavelength 

filter, and binning.



UR directory:

This CDR6 gives uncertainty in absolute and relative sphere signal, for each 

bulb. This product is not a part of the nominal data processing pipeline and 

its creation is TBD; it is intended for end users of calibrated data as an 

indication of limits to data interpretation.



VL directory:

This CDR6 This file gives the 14-bit DN at which each detector - ON AVERAGE 

- is   saturated. It is used together with the predicted limiting case 

expected 14-bit scene DN levels (in the AS directory) to produce bad pixel 

maps. It also gives additional criteria for defining a bad pixel, thresholds 

for noise and relative pixel response.



WA directory:

This CDR4 gives the center wavelength for each detector element. There is a 

different version for each detector, wavelength filter, and binning.



WV directory:

This CDR6 gives the table of detector rows (bands) loaded into wavelength 

filters 0-3. There is one version for each detector.



The file naming convention for level-6 CDRs is as follows.

(ProductType)(Level)_(Partition)_(Time)_(Product)_(SensorID)_version.(Ext)

where:

Product Type = CDR

Level = 6

Partition = n, partition of the spacecraft clock. 

Time = nnnnnnnnnn, spacecraft start time of applicability of data product; 

units are spacecraft clock counts, in units of whole seconds. 

Product = nn, acronym describing data product from Table 3-3

Sensor ID = S or L (or J=joint)

Version = 0, 1,..., 9, a,..., z

Ext = TAB 



The file naming convention for level-4 CDRs is as follows.

(ProductType)(Level)(Partition)(Time)_ 

(Product)(FrameRate)(Binning)(ExposureParameter)(WavelengthFilter)(Side)(Sens

orID)_ version.(Ext)

where:

Product Type = CDR 

Level = 4

FrameRate = n, rate in Hz at which data are taken (0=1 Hz, 1=3.75 Hz, 3=156 

Hz, 4=30 Hz, 5 = N/A)

Binning = n, number of spatial pixels binned (0=unbinned, 1= 2x binned, 2= 5x 

binned, 3= 10x binned, 4=N/A)

Exposure parameter = nnn, an integer 1-480 indicating commanded exposure time 

in units of (inverse frame rate)/480; 000 if inapplicable

Wavelength filter = n, and integer 0-3 indicating which onboard menu of rows 

of the detector are represented

Side = #, 1 or 2 for focal plane or sphere bulbs; or 0 if N/A

Ext  = IMG 



The tables in the YYYY_DOY/ATF and YYYY_DOY/BTF directories have a different 

file naming convention, as follows.

(Product)_(Sensor)_(YYYY)_(DOY)_version

where:

Product Type = BTF for predicted or ATF for actual

Sensor = VN or IR

YYYY = year

DOY = day of year

Version = nn