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:
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.
- Nominal, or spectra, frames consist of six spectra with sixteen channels each
at two bytes per channel.
- 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.
- Status frames, or HEND instrument commands.
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.