Overview of Uncalibrated Data

Uncalibrated data are raw data that has had associated timing and spatial information added. A full description may be found in the 2001 Mars Odyssey Gamma Ray Spectrometer EDR NASA Level 0 Software Interface Specification (EDR SIS).

Uncalibrated Gamma Spectra

The uncalibrated gamma spectra data are composed of the raw, uncorrected gamma spectra and associated timing and spatial information. The spectra consists of the cumulative counts of gamma rays at the detector over one pixel, binned into 16,384 channels, based on energy. The times listed (sc_ev_time, UTC time, and spatial fields) all denote the center of the collection interval (also called a "pixel").

Uncalibrated Neutron Spectra

Neutron spectra consists of fifteen histograms, event data, and associated timing and spatial information. The neutron event data consists of the cumulative counts of neutrons detected at one of four prisms over a collection interval. The times listed (sc_ev_time, UTC time, and spatial fields) all denote the center of the collection interval.

Uncalibrated HEND Spectra

HEND spectral data consists of HEND records and associated timing and spatial information. HEND rcords, also called frames, may be one of three types:
  1. Nominal, or spectra, frames consist of six spectra with sixteen channels each at two bytes per channel.

  2. Profile, or time series, frames consist of the six spectra pus two time profiles. The inner scintillator profile is thirty seconds in duration, with a count for each second. The outer scintillator profile is also thirty seconds in duration, but has a time resolution of 0.25 seconds, with a count for each interval.

  3. Status frames, or HEND instrument commands.
The timing and spatial data provided with the HEND data includes spacecraft clock values and spacecraft geometry data. The SC_EV_TIME, UTC time and spatial fields are all recorded at the center of the collection interval.

Gamma-Ray Burst Profile Data

Profile Data is comprised of information about gamma-ray bursts as detected by the Gamma-Ray Spectrometer's Gamma Sensor head (GS). These data are used by astrophysicists in conjunction with Gamma-Ray Burst (GRB) data from other spacecraft and Earth-based instruments to locate and study these phenomena. This data is not used to study the planet Mars.

Engineering and Other Data

The Pulser Spectra, Command List, Message Log, E Kernel, Channelized, and Engineering data sets provide supporting information on the Gamma-Ray Spectrometer's commands, hardware status, and information used in spectral calibration routines.