Derived Neutron Data

The DND product contains normalized neutron counting rates for all four of the Neutron Spectrometer prisms, from which thermal and epithermal neutron count rates are determined. Thermal and epithermal count rates are included in the data set. Background-corrected and normalized fast counting data are also provided for the nadir-looking prism (Prism 1). The data is presented in a table format with one row of data for each NS collection interval within a 24 Earth hour period. The DND data can be used along with models and calibration procedures described in the literature [Feldman et al., 2003; Prettyman et al., 2004] to study the composition and structure of the surface and atmosphere of Mars on sub-seasonal time scales.

Column Descriptions
Column Name Type Bytes Units
SC_RECV_TIME MSB_UNSIGNED_INTEGER 8
The time this packet was received by the spacecraft, in ticks (256 per second).
CEB_TIME MSB_UNSIGNED_INTEGER 8
Clock count from the GRS Common Electronics Box at the beginning of the pixel.
UTC CHARACTER 23
Time at the middle of the collection interval converted to UTC, stored as yyyy-mm-ddThh:mm:ss.sss.
GRS_PIXEL_NUMBER MSB_UNSIGNED_INTEGER 4
Sequential counter of accumulation intervals, starts with one as grs orbit begins. Special case on reboot when the the CEB is in orbit 0, pixel 0.
GRS_ORBIT_NUMBER MSB_UNSIGNED_INTEGER 4
Sequential counter of orbits from GRS CEB boot.
ODY_ORBIT_NUMBER MSB_UNSIGNED_INTEGER 4
Orbit number common to all instruments aboard Odyssey. This orbit number is incremented by one as the spacecraft passes through the orbital descending node.
AREOCENTRIC_LATITUDE IEEE_REAL 4 DEGREE
Sub spacecraft latitude in Mars fixed coordinates at the middle of the collection interval.
AREOCENTRIC_EAST_LONGITUDE IEEE_REAL 4 DEGREE
Sub spacecraft longitude in Mars fixed coordinates at the middle of the collection interval. Longitude increases towards the East.
ALTITUDE IEEE_REAL 4 KILOMETER
Areocentric altitude of the sub-spacecraft point in Mars-fixed rotating frame at the middle of the collection interval.
SCPOS_INERT IEEE_REAL 12 KILOMETER
The geometric position (x,y,z) of the spacecraft with respect to Mars in the 'MARSIAU' IAU2000 reference system inertial frame at the input epoch 'et' at the middle of the pixel.
SCVEL_INERT IEEE_REAL 12 "KILOMETER/SECOND"
The geometric velocity (x,y,z) of the spacecraft with respect to Mars in the 'MARSIAU' IAU2000 reference system inertial frame at the input epoch 'et' at the middle of the pixel.
MARSPOS_INSTR IEEE_REAL 12 KILOMETER
The (x,y,z) position of the sub-spacecraft point as seen from the spacecraft in the instrument frame at the middle of the collection interval. If no spacecraft orientation data was available from the loaded CK files for the request time, then all elements of are set to zero.
MARSVEL_INSTR IEEE_REAL 12 "KILOMETER/SECOND"
Contains the inertial spacecraft velocity direction (x,y,z) rotated to the instrument frame at the middle of the collection interval. If no spacecraft orientation data was available for the request time, then all elements are set to zero.
DAY_INDEX MSB_UNSIGNED_INTEGER 2
Day of Martian year.
LOCAL_HOUR MSB_UNSIGNED_INTEGER 2
Local Sun hour at the sub-spacecraft point.
LOCAL_MINUTE MSB_UNSIGNED_INTEGER 2
Local Sun minute at the sub-spacecraft point.
PIXEL_DURATION IEEE_REAL 4 SECOND
Length of the collection interval in seconds.
POWER_SUPPLY MSB_UNSIGNED_INTEGER 2
Which power supply is being used, 1 or 2.
SWAP_FLAG MSB_UNSIGNED_INTEGER 2
The state of the prompt/delayed swap flag.
POWER_LEVEL MSB_UNSIGNED_INTEGER 2
The power level of the power supply in use during the collection interval, 1 being highest power and 7 being lowest power.
DIRECTION MSB_UNSIGNED_INTEGER 1
Direction of spacecraft travel N(1) or S(0).
LIVETIME IEEE_REAL 4 SECOND
In seconds, duration - deadtime, where deadtime = dead_cnt * .000512 sec.
DEADTIME_PERCENT IEEE_REAL 4
Deadtime / duration.
OVERLOAD_RATE IEEE_REAL 4
The galactic cosmic ray flux measured at the neutron spectrometer. (gcr_cnt / (110 cm*cm) / (duration sec)). Units are square centimeter per second.
HVPS_MNTR_2 IEEE_REAL 4 VOLT
The value of the High Voltage Power Supply Monitor 2 at the mid point of the collection interval that has been smoothed with a Gaussian weighted smoothing algorithm over 30 HVPS_MNTR_2 measurements and interpolated to the time at the middle of the NS collection interval from the HVPS_MNTR_2 engineering measurement that happens just before the NS collection interval and the one just after the NS collection interval.
LAT_1 IEEE_REAL 4 DEGREE
Latitude in degrees to be associated with CAT1, Prism 1 count rate and error
LON_1 IEEE_REAL 4 DEGREE
Longitude in degrees to be associated with CAT1, Prism 1 count rate and error
LAT_4_5 IEEE_REAL 4 DEGREE
Latitude in degrees to be associated with the thermal count rate and error
LON_4_5 IEEE_REAL 4 DEGREE
Longitude in degrees to be associated with the thermal count rate and error
CAT1_PRISM1_PEAK_AREA IEEE_REAL 4
The counting rate given by the area in the 10B(n,alpha)7Li reaction peak above background registered by prism 1, in units of s^-1. The counting rate as measured is normalized by the ratio of the average Cat1 Prism1 counting rate averaged over all transits between +30 degrees and -30 degrees latitude measured within +0.5 and -0.5 days of the current data point. This counting rate is also the epithermal neutron counting rate.
CAT1_PRISM1_ERROR IEEE_REAL 4
The 1-sigma statistical error of the CAT1_PRISM1_PEAK_AREA (counts/s).
CAT1_PRISM2_PEAK_AREA IEEE_REAL 4
The counting rate given by the area in the 10B(n,alpha)7Li reaction peak above background registered by prism 2, in units of s^-1. The counting rate as measured is normalized by the ratio of the average Cat1 Prism2 counting rate averaged over all transits between +30 degrees and -30 degrees latitude measured within +0.5 and -0.5 days of the current data point.
CAT1_PRISM2_ERROR IEEE_REAL 4
The 1-sigma statistical error of the CAT1_PRISM2_PEAK_AREA (counts/s).
CAT1_PRISM3_PEAK_AREA IEEE_REAL 4
The counting rate given by the area in the 10B(n,alpha)7Li reaction peak above background registered by prism 3, in units of s^-1. The counting rate as measured is normalized by the ratio of the average Cat1 Prism3 counting rate averaged over all transits between +30 degrees and -30 degrees latitude measured within +0.5 and -0.5 days of the current data point.
CAT1_PRISM3_ERROR IEEE_REAL 4
The 1-sigma statistical error of the CAT1_PRISM3_PEAK_AREA (counts/s).
CAT1_PRISM4_PEAK_AREA IEEE_REAL 4
The counting rate given by the area in the 10B(n,alpha)7Li reaction peak above background registered by prism 4, in units of s^-1. The counting rate as measured is normalized by the ratio of the average Cat1 Prism4 counting rate averaged over all transits between +30 degrees and -30 degrees latitude measured within +0.5 and -0.5 days of the current data point.
CAT1_PRISM4_ERROR IEEE_REAL 4
The 1-sigma statistical error of the CAT1_PRISM4_PEAK_AREA (counts/s).
CAT2_PRISM1_FAST_SUM IEEE_REAL 4
The sum of the counting rate in the lowest two channels of the [(early-time) - (late time)] fast-neutron histograms, in units of s^-1. The counting rate as measured is normalized by the ratio of the average CAT2_PRISM1_FAST_SUM counting rate averaged over all transits between +30 degrees and -30 degrees latitude measured within +0.5 and -0.5 days of the current data point.
CAT2_PRISM1_ERROR IEEE_REAL 4
The 1-sigma statistical error of the CAT2_PRISM1_FAST_SUM (counts/s).
THERMAL_COUNT_RATE IEEE_REAL 4
The difference between CAT1_PRISM2_Peak_Area and CAT1_PRISM4_Peak_Area, in units of s^-1. The counting rate as measured is normalized by the ratio of the Thermal Count Rate averaged over all transits between +30 degrees and -30 degrees latitude measured within +0.5 and -0.5 days of the current data point.
THERMAL_ERROR IEEE_REAL 4
The 1-sigma statistical error of the THERMAL_COUNT_RATE (counts/s)
CAT1_PRISM1_NORM_SLOPE IEEE_REAL 4
The slope parameter for the bellyband normalization for the CAT1_PRISM1_PEAK_AREA.
CAT1_PRISM1_NORM_OFFSET IEEE_REAL 4
The offset parameter for the bellyband normalization for the CAT1_PRISM1_PEAK_AREA.
CAT1_PRISM2_NORM_SLOPE IEEE_REAL 4
The slope parameter for the bellyband normalization for the CAT1_PRISM2_PEAK_AREA.
CAT1_PRISM2_NORM_OFFSET IEEE_REAL 4
The offset parameter for the bellyband normalization for the CAT1_PRISM2_PEAK_AREA.
CAT1_PRISM3_NORM_SLOPE IEEE_REAL 4
The slope parameter for the bellyband normalization for the CAT1_PRISM3_PEAK_AREA.
CAT1_PRISM3_NORM_OFFSET IEEE_REAL 4
The offset parameter for the bellyband normalization for the CAT1_PRISM3_PEAK_AREA.
CAT1_PRISM4_NORM_SLOPE IEEE_REAL 4
The slope parameter for the bellyband normalization for the CAT1_PRISM4_PEAK_AREA.
CAT1_PRISM4_NORM_OFFSET IEEE_REAL 4
The offset parameter for the bellyband normalization for the CAT1_PRISM4_PEAK_AREA.
CAT2_PRISM1_NORM_SLOPE IEEE_REAL 4
The slope parameter for the bellyband normalization for the CAT2_PRISM1_FAST_SUM.
CAT2_PRISM1_NORM_OFFSET IEEE_REAL 4
The offset parameter for the bellyband normalization for the CAT2_PRISM1_FAST_SUM.
CF_ATM_EPI IEEE_REAL 4
Correction factor for atmospheric mass for epithermal neutrons.
CF_ATM_FAST IEEE_REAL 4
Correction factor for atmospheric mass for fast neutrons.