Neutron Spectra

The NS data are time series records taken over the course of a day. Data files are labeled with the date. Individual records are composed of 15 histograms, event data and the associated timing and spatial information. The neutron event data are the cumulative counts of neutrons detected at 1 of four prisms over the collection interval. The collection interval is approximately 19.7 seconds, but may vary over the course of mapping. The timing and spatial data provided with the neutron spectra includes spacecraft clock values and spacecraft spatial data. The sc_ev_time, utc time and geometry fields are all recorded at the center of the collection interval.

Column Descriptions
Column Name Type Bytes Units
BAD_CODE MSB_UNSIGNED_INTEGER 4
If non-zero, the data has been flagged bad. Definitions in bad_code.txt.
COUNTER MSB_UNSIGNED_INTEGER 1
The packet counter from the lanl pkt, values from 0 to 15.
NS_COMPRESSED MSB_UNSIGNED_INTEGER 1
indicates if LANL compression algorithm was used on this data.
GRS_COMPRESSED MSB_UNSIGNED_INTEGER 1
indicates if GAMMA compression algorithm was used on this data.
NS_INSTRUMENT_MEMORY_SIDE MSB_UNSIGNED_INTEGER 2
Memory side data is coming from.
EARLY_TIME MSB_UNSIGNED_INTEGER 2
Early time register.
LATE_TIME MSB_UNSIGNED_INTEGER 2
Late time register.
DEAD_CNT MSB_UNSIGNED_INTEGER 8
Dead count.
GCR_CNT MSB_UNSIGNED_INTEGER 2
Galactic cosmic ray count.
EARLY_2ND_PULSE_CNT MSB_UNSIGNED_INTEGER 2
Early time to second pulse count.
CAT1_3SEG_CNT MSB_UNSIGNED_INTEGER 2
Category 1, 3 prism event count
CAT1_4SEG_CNT MSB_UNSIGNED_INTEGER 2
Category 1, 4 prism event count.
CAT2_3SEG_CNT MSB_UNSIGNED_INTEGER 2
Category 2, 3 prism event count.
CAT2_4SEG_CNT MSB_UNSIGNED_INTEGER 2
Category 2, 4 prism event count.
CAT2_CNT MSB_UNSIGNED_INTEGER 2
Category 2 event count.
CAT1_1_HIST MSB_UNSIGNED_INTEGER 128
Category 1 histogram 1.
CAT1_2_HIST MSB_UNSIGNED_INTEGER 128
Category 1 histogram 2.
CAT1_3_HIST MSB_UNSIGNED_INTEGER 128
Category 1 histogram 3.
CAT1_4_HIST MSB_UNSIGNED_INTEGER 128
Category 1 histogram 4.
CAT1_SUM_HIST MSB_UNSIGNED_INTEGER 128
Category 1 summation histogram.
CAT2_EARLY_1_HIST MSB_UNSIGNED_INTEGER 32
Category 2 early time histogram 1.
CAT2_EARLY_2_HIST MSB_UNSIGNED_INTEGER 32
Category 2 early time histogram 2.
CAT2_EARLY_3_HIST MSB_UNSIGNED_INTEGER 32
Category 2 early time histogram 3.
CAT2_EARLY_4_HIST MSB_UNSIGNED_INTEGER 32
Category 2 early time histogram 4.
CAT2_EARLY_SUM_HIST MSB_UNSIGNED_INTEGER 32
Category 2 early time summation histogram.
CAT2_LATE_1_HIST MSB_UNSIGNED_INTEGER 32
Category 2 late time histogram 1.
CAT2_LATE_2_HIST MSB_UNSIGNED_INTEGER 32
Category 2 late time histogram 2.
CAT2_LATE_3_HIST MSB_UNSIGNED_INTEGER 32
Category 2 late time histogram 3.
CAT2_LATE_4_HIST MSB_UNSIGNED_INTEGER 32
Category 2 late time histogram 4.
CAT2_LATE_SUM_HIST MSB_UNSIGNED_INTEGER 32
Category 2 late time summation histogram.
SC_RECV_TIME MSB_UNSIGNED_INTEGER 8
The time this packet was received by the spacecraft, in ticks (256 per second).
SC_EV_TIME MSB_UNSIGNED_INTEGER 8
Spacecraft time at the middle of the pixel, in ticks.
CEB_TIME MSB_UNSIGNED_INTEGER 8 MILLISECOND
Clock count from the GRS Common Electronics Box at the beginning of the pixel.
UTC CHARACTER 23
SC_EV_TIME 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.
LATITUDE IEEE_REAL 8
Sub spacecraft latitude in Mars fixed coordinates at the middle of the pixel.
LONGITUDE IEEE_REAL 8
Sub spacecraft longitude in Mars fixed coordinates at the middle of the pixel.
SCPOS_INERT IEEE_REAL 24 KILOMETER
The geometric position (x,y,z) of the spacecraft with respect to Mars in the 'MARSIAU' inertial frame at the input epoch 'et' at the middle of the pixel.
SCVEL_INERT IEEE_REAL 24 "KILOMETER/SECOND"
The geometric velocity (x,y,z) of the spacecraft with respect to Mars in the 'MARSIAU' inertial frame at the input epoch 'et' at the middle of the pixel.
MARSPOS_INSTR IEEE_REAL 24 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 pixel. 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 24 "KILOMETER/SECOND"
Contains the inertial spacecraft velocity direction (x,y,z) rotated to the instrument frame at the middle of the pixel. If no spacecraft orientation data was available for the request time, then all elements are set to zero.
SCPOS_MARS IEEE_REAL 24 KILOMETER
Spacecraft position (x,y,z) in Mars fixed coordinates at the middle of the pixel.
INSTR_BORESIGHT_MARS IEEE_REAL 24 KILOMETER
Sub instrument boresight (x,y,z) in Mars fixed coordinates at the middle of the pixel.
SUB_SCPOS_MARS IEEE_REAL 24 KILOMETER
Sub spacecraft vector (x,y,z) in Mars fixed coordinates at the middle of the pixel.
SCALT IEEE_REAL 8 KILOMETER
Areocentric altitude of the sub-spacecraft point in Mars-fixed rotating frame at the middle of the pixel.
DELTA_ANGLE IEEE_REAL 8 DEGREE
Difference between instrument +y direction and true north at the middle of the pixel. Currently not computed for NEUTRON_SPECTRA and HEND_SPECTRA.
MARS_SOL IEEE_REAL 8
Longitude of the Sun at 0 hours UT on the date of the record. Taken from the Association of Lunar and Planetary Observers 'Ephemeris for Physical Observation of Mars'.
DAY_INDEX MSB_UNSIGNED_INTEGER 2
Day of Martian year.
LOCAL_HOUR MSB_UNSIGNED_INTEGER 1
Local Sun hour at the sub-spacecraft point.
LOCAL_MINUTE MSB_UNSIGNED_INTEGER 1
Local Sun minute at the sub-spacecraft point.
POINTING BOOLEAN 1
True if pointing data was available.
INTERSECTING BOOLEAN 1
True if the pointing vector intersects Mars.