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 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. |