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Data Access
Polar TIMAS K2 data repository
Polar TIMAS K2 Mass Spectral Data
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(2025).
Polar TIMAS K2 Mass Spectral Data.
[Data set].
Laboratory for Atmospheric and Space Physics.
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ResourceID
spase://NASA/NumericalData/POLAR/TIMAS/K2/PT192S
Description
Mass spectra count rates for survey purposes only from the POLAR TIMAS instrument. The mass spectral data product consists of 64 mass steps covering the full detector range, for each of 6 large solid angles, for 8 selected energy steps. The data product is accumulated for 2, 4, 8, 16, or 32 spin (6 s) periods. Because of telemetry restrictions only selected data products were telemetered to the ground.
The 6 angular bins cover the full instrumental range and nearly 4pi steradians. Two of the look directions are centered on the spacecraft spin axis. For the first part of the mission, the spin axis was orbit normal and the pitch angles sampled in these look directions are near 90 degrees. The other 4 look directions are in the spin plane. Data are de-spun on board based on the spin rate and time of the "sun pulse". The digital data product provides the center pitch angle of each of the 6 look directions and an estimate of the variation of the pitch angle during the accumulation time.
Reference: E.G. Shelley et al., The Toroidal Imaging Mass-Angle Spectrograph (TIMAS) for the Polar Mission, Sp. Sci. Rev, Vol 71, pp 497-530, 1995.
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Version:2.7.1
NumericalData
ResourceID
spase://NASA/NumericalData/POLAR/TIMAS/K2/PT192S
NamingAuthority
NASA
ResourceType
NumericalData
ResourceHeader
ResourceName
Polar TIMAS K2 Mass Spectral Data
DOI
https://doi.org/10.48322/xm8x-tc98
ReleaseDate
2026-02-12 23:59:30Z
RevisionHistory
RevisionEvent
ReleaseDate
2020-07-07 21:15:02Z
Note
Only known prior ReleaseDate of the metadata
RevisionEvent
ReleaseDate
2025-11-14 16:01:53Z
Note
Added PublicationInfo. Added ResourceType and NamingAuthority. Changed http to https in top-level schemaLocation attribute. Fixed version number separator in top-level schemaLocation attribute. Matched version number in schemaLocation attribute to updated value in Version tag. ZCB
RevisionEvent
ReleaseDate
2025-12-04 13:31:03Z
Note
Added MetadataRightsList. Updated to 2.7.1. ZCB
RevisionEvent
ReleaseDate
2026-02-12 23:59:30Z
Note
Added DOI. tlk
Description
Mass spectra count rates for survey purposes only from the POLAR TIMAS instrument. The mass spectral data product consists of 64 mass steps covering the full detector range, for each of 6 large solid angles, for 8 selected energy steps. The data product is accumulated for 2, 4, 8, 16, or 32 spin (6 s) periods. Because of telemetry restrictions only selected data products were telemetered to the ground.
The 6 angular bins cover the full instrumental range and nearly 4pi steradians. Two of the look directions are centered on the spacecraft spin axis. For the first part of the mission, the spin axis was orbit normal and the pitch angles sampled in these look directions are near 90 degrees. The other 4 look directions are in the spin plane. Data are de-spun on board based on the spin rate and time of the "sun pulse". The digital data product provides the center pitch angle of each of the 6 look directions and an estimate of the variation of the pitch angle during the accumulation time.
Reference: E.G. Shelley et al., The Toroidal Imaging Mass-Angle Spectrograph (TIMAS) for the Polar Mission, Sp. Sci. Rev, Vol 71, pp 497-530, 1995.
PublicationInfo
Authors
Peterson, W. K.
PublicationDate
2025-11-14 16:01:53Z
PublishedBy
Laboratory for Atmospheric and Space Physics
Contacts
Role
Person
StartDate
StopDate
Note
1.
PrincipalInvestigator
spase://SMWG/Person/W.K.Peterson
InformationURL
Name
TIMAS Home Page
URL
http://lasp.colorado.edu/home/timas/full/
InformationURL
Name
TIMAS K2 product page
URL
http://lasp.colorado.edu/timas/info/k2/k2.html
InformationURL
Name
Lennartsson et al., Adv. Space Res., 2000
URL
http://lasp.colorado.edu/media/projects/timas/pdf/COSPAR98.pdf
Description
Polar/TIMAS Statistical Results on the Outflow of Molecular Ions From Earth at Solar Minimum, O.W. Lennartsson, H.L. Collin, W.K. Peterson, and E.G. Shelley, Advances in Space Research, 25, 2417, 2000.
InformationURL
Name
Lennartsson et al., JASTP, 2000
URL
http://lasp.colorado.edu/media/projects/timas/pdf/Molecular_two.pdf
Description
A Statistical Comparison of the Outflow of N2+, NO+, and O2+ Molecular Ions with that of Atomic O+ Ions using Polar/TIMAS Observations, O.W. Lennartsson, H.L. Collin, A.G. Ghielmetti, and W.K. Peterson, Journal of Atmospheric and Solar-Terrestrial Physics (JASTP), 62, 477, 2000.
PriorIDs
spase://VMO/NumericalData/POLAR/TIMAS/K2_PT192S
spase://VSPO/NumericalData/POLAR/TIMAS/K2/PT192S
AccessInformation
RepositoryID
spase://SMWG/Repository/UCOLO/LASP/TIMAS_K2
AccessURL
Name
Polar TIMAS K2 data repository
URL
http://lasp.colorado.edu/timas/data/k2/
Description
Repository of Polar TIMAS K2 data in CDF format at LASP
Format
CDF
ProviderVersion
v_01
InstrumentIDs
spase://SMWG/Instrument/POLAR/TIMAS
MeasurementType
EnergeticParticles
MeasurementType
IonComposition
MeasurementType
Spectrum
MeasurementType
ThermalPlasma
TemporalDescription
TimeSpan
StartDate
1996-03-16 12:47:36Z
StopDate
2006-05-28 23:57:58Z
Cadence
PT192S
ObservedRegion
Earth.Magnetosphere
ObservedRegion
Earth.Magnetosphere.Polar
ObservedRegion
Earth.Magnetosphere.RadiationBelt
Caveats
The data in the "Mass_Spectra" variable are in counts per accumulation interval. Conversion to flux units requires a detailed understanding of the detector system described in the TIMAS instrument description.
Data are available for most, but not all, days between March 17, 1996 and May 31, 2006. Data are missing for several reasons including: TIMAS high voltage off, Magnetometer key parameter data are not availble to calculate pitch angles, and a problem with telemetry described below.
On December 8, 1998 the TIMAS instrument suffered a high voltage breakdown that significantlty reduced the instrumental sensitivity. After this time the instrumental response to ions with energies less than ~800 eV is extremely weak and non linear.
From November 1999 through March 30, 2001, TIMAS data were intermittent because of an intermittent connection in the telemetry lines on the satellite. The problem was resolved with a shift to the redundant telemetry system on March 30, 2001.
Parameter #1
Name
Epoch
ParameterKey
Center_Epoch
Description
NSSDC standard reference time value at the center of the accumulation interval.
Units
ms (UT)
ValidMin
01-Jan-1995 00:00:00.000
ValidMax
01-Jan-2020 23:59:59.999
FillValue
-1.0E31
Support
SupportQuantity
Temporal
Parameter #2
Name
Start Epoch
ParameterKey
Start_Epoch
Description
NSSDC standard-reference time value at the start of the accumulation interval.
Units
ms (UT)
ValidMin
17-Mar-1996 00:00:00.000
ValidMax
17-Apr-2008 23:59:59.999
FillValue
-1.0E31
Support
SupportQuantity
Temporal
Parameter #3
Name
Stop Epoch
ParameterKey
Stop_Epoch
Description
NSSDC standard-reference time value at the end of the accumulation interval.
Units
ms (UT)
ValidMin
01-Jan-1995 00:00:00.000
ValidMax
01-Jan-2020 23:59:59.999
FillValue
-1.0E31
Support
SupportQuantity
Temporal
Parameter #4
Name
Counts
ParameterKey
Mass_Spectra
Description
An array of counts per mass step for each data accumulation interval. The array has dimensions for
* 6 angular accumulation bins covering the full angular range of the instrument. The pitch angles sampled in each of these bins is given by the "Pitch_Angles" variable and associated quality parameters described below.
* 8 energy step bins. The measurement energies associated with each energy step are mode dependent. They are given by the "Energy" variable and associated quality parameters described below.
* 64 mass steps. The position of H+, He++, He+, O+, NO+, and other species in mass step space depends on the MS ELUT (Mass Spectra Energy Look Up Table) which is mode dependent. MS ELUT's are specified for each TIMAS mode. The TIMAS mode is identified by the "ICP" data variable described below.
Units
Counts per Spin
Structure
Size
6 8 64
Particle
ParticleType
Proton
ParticleType
AlphaParticle
ParticleType
Ion
ParticleType
Molecule
ParticleQuantity
Counts
AtomicNumber
1
AtomicNumber
2
AtomicNumber
7
AtomicNumber
8
Parameter #5
Name
ID of Mass Spectral Energy Look Up Table
ParameterKey
Energy_LUT
Description
A two digit number identifing the MS ELUT that determines which 8 of the 28 possible TIMAS energy steps are mapped to the 8 energy bins in the "Mass_Spectra" variable. MS ELUT's are specified for each TIMAS mode. The TIMAS mode is given by the "ICP" data variable described below.
ValidMin
9
ValidMax
64
Support
SupportQuantity
Other
Parameter #6
Name
Ion Energy at center of energy band
ParameterKey
Energy
Description
Energy ABOVE Space Craft Potential. An array of 8 energies (in eV) giving the center energies of the data in the "Mass_Spectra" variable in each of the 8 energy step bins for each accumulation interval.
Units
eV
Structure
Size
8
ValidMin
15.0
ValidMax
35000.0
Support
SupportQuantity
Other
Parameter #7
Name
Composition of energy channel
ParameterKey
Energy_Status
Description
A quality parameter:
* 0: All data from same instrumental energy step.
* 1: Data have been accumulated from multiple instrumental energy steps.
* 99 or 255: Invalid energies.
Structure
Size
8
ValidMin
0.0
ValidMax
99.0
Support
SupportQuantity
Other
Parameter #8
Name
Upper Energy
ParameterKey
Upper_Energy
Description
An array of 8 energies (in eV) giving the upper energies of the data in the "Mass_Spectra" variable in each of the 8 energy step bins for each accumulation interval.
Units
eV/e
Structure
Size
8
ValidMin
15.0
ValidMax
35000.0
Support
SupportQuantity
Other
Parameter #9
Name
Lower Energy
ParameterKey
Lower_Energy
Description
An array of 8 energies (in eV) giving the lower energies of the data in the "Mass_Spectra" variable in each of the 8 energy step bins for each accumulation interval.
Units
eV
Structure
Size
8
ValidMin
15.0
ValidMax
35000.0
Support
SupportQuantity
Other
Parameter #10
Name
Quality of Pitch angle data
ParameterKey
PA_Status
Description
A quality indicator of the "Pitch_Angles" variables for each accumulation interval.
* 0: Valid pitch angles.
* 4: Pitch angle data compromised (smeared) because of no "spin lock."
* 10: Insufficient data to calculate pitch angle.
* 99: Invalid pitch angles.
* 100: No magnetometer data (required to calculate pitch angle).
ValidMin
0.0
ValidMax
100.0
Support
SupportQuantity
Other
Parameter #11
Name
Pitch Angle
ParameterKey
Pitch_Angles
Description
An array of 6 pitch angles (in degrees) giving the pitch angle at the center of each of the 6 rather large angular accumulation bins in the "Mass_Spectra" variable.
Caveats
Pitch angles at center of FoV (field-of-view)
Units
Degrees
Structure
Size
6
ValidMin
0.0
ValidMax
180.0
Support
SupportQuantity
Other
Parameter #12
Name
Look Directions in Fixed Platform Coordinates
ParameterKey
Look_Directions
Description
Look directions of the 6 angular sectors In Fixed Payload Coordinates.
Normal operations have the angular accumulation bins for the "Mass_Spectra" variable fixed in "Fixed Platform" coordinates. The 6 look directions in FP coordinates defined by the MAG team are:
* 1: in the + Z (spin axis) direction,
* 2: in the +X direction, (in the spin plane, in the direction closest to the sun direction),
* 3: +Y direction (completing a right hand coordiante system),
* 4: -X direction,
* 5: -Y direction, and
* 6: -Z (spin axis) direction.
For the first part of the mission the spin axis was orbit normal and so the +/- Z axes sampled mostly near 90 degree pitch angles. Later in the mission the spin axis was pointed nearly normal to the ecliptic.
Caveats
This parameter contains no data.
Structure
Size
6 3
Support
SupportQuantity
Other
Parameter #13
Name
Pitch Angle DRIFT
ParameterKey
PA_Drift
Description
An array of 6 angles (in degrees) giving the change in magnitude of the pitch angle at the center of each angular accumulation bin over each accumulation interval.
Units
Degrees
Structure
Size
6
ValidMin
0.0
ValidMax
180.0
Support
SupportQuantity
Other
Parameter #14
Name
Mass Step
ParameterKey
Mass
Description
Numbers from 0 to 63 giving the mass step number for each of the 64 mass steps in the "Mass_Spectra" variable.
Structure
Size
64
ValidMin
0.0
ValidMax
63.0
Support
SupportQuantity
Other
Parameter #15
Name
ICP table number
ParameterKey
ICP
Description
A two digit number indicating the TIMAS operating mode.
ValidMin
0.0
ValidMax
256.0
FillValue
-1.0E31
Support
SupportQuantity
Other
Parameter #16
Name
Energy Range
ParameterKey
Energy_Range_ID
Description
A variable indicating which of the three TIMAS energy range modes was active at the time of data acumulation.
* 0: Data for the full (15eV to 33 keV) energy range was acquired.
* 1: Data for a reduced (15 eV to 25 keV) energy range was acquired.
* 2: Data were sampled only for the lowest energies. Data acquired in this mode has not been validated.
ValidMin
0
ValidMax
3
FillValue
255
Support
SupportQuantity
Other
Parameter #17
Name
FEC counts
ParameterKey
FEC
Description
Total counts per spin in the fast event counter
Caveats
The TIMAS detector has a non linear response at high count rates that is, to some extent corrected for in the software that generated the data here. The correction, however introduces some uncertainty. The FEC count rate is carried as an indication of the corrections applied to the raw data.
Units
Counts per spin
ValidMin
0.0
ValidMax
1.0E8
FillValue
-1.0E31
Support
SupportQuantity
Other
Parameter #18
Name
Background counts
ParameterKey
BCR
Description
Total Background counts per spin
Units
Counts per spin
ValidMin
0.0
ValidMax
1.0E8
FillValue
-1.0E31
Support
SupportQuantity
Other
Parameter #19
Name
Accumulated spins in each energy band
ParameterKey
Spins
Description
Number of 6 second spin periods in the accumulation interval for the "Mass_Spectra" variable.
Units
Number of spin periods
Structure
Size
8
ValidMin
0.0
ValidMax
32.0
FillValue
-1.0E31
Support
SupportQuantity
Other
Parameter #20
Name
Data Quality Flag
ParameterKey
Quality
Description
A 2-digit quality number for the "Mass_Spectra" variable.
* 0: OK;
* 1: Some data missing;
* 5: Some warning flags were set;
* 99: No valid data.
0 and 1 indicated high quality data.
ValidMin
0
ValidMax
99
FillValue
255
Support
SupportQuantity
Other
Parameter #21
Name
Quality of Orbit Information
ParameterKey
Orbit_Status
Description
A quality number for the orbital data.
* 0: OK,
* 99: Orbit data not available.
ValidMin
0.0
ValidMax
99.0
Support
SupportQuantity
Other
Parameter #22
Name
L value
ParameterKey
L
Description
The MacIlwain L parameter associated with the "Center_Epoch" of the data accumulation interval.
ValidMin
0.0
ValidMax
100000.0
FillValue
-1.0E31
Support
SupportQuantity
Positional
Parameter #23
Name
Magnetic Local Time
ParameterKey
MLT
Description
The magnetic local time associated with the "Center_Epoch" of the data accumulation interval.
Units
hours
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
SM
ValidMin
0.0
ValidMax
25.0
FillValue
-1.0E31
Support
Qualifier
DirectionAngle.AzimuthAngle
SupportQuantity
Positional
Parameter #24
Name
Local Time
ParameterKey
Ltime
Description
The local time associated with the "Center_Epoch" of the data accumulation interval.
Units
hours
ValidMin
0.0
ValidMax
25.0
FillValue
-1.0E31
Support
SupportQuantity
Temporal
Parameter #25
Name
Geocentric Distance
ParameterKey
RE
Description
The geocentric distance (in units of Earth radii) of the Polar satellite associated with the "Center_Epoch" of the data accumulation interval.
Units
Re
UnitsConversion
6.370e6>m
ValidMin
1.0
ValidMax
12.0
FillValue
-1.0E31
Support
SupportQuantity
Positional
Parameter #26
Name
Magnetic Latitude
ParameterKey
Mlat
Description
The magnetic latitude (in degrees) associated with the "Center_Epoch" of the data accumulation interval.
Units
degrees
CoordinateSystem
CoordinateRepresentation
Spherical
CoordinateSystemName
SM
ValidMin
-90.0
ValidMax
90.0
FillValue
-1.0E31
Support
Qualifier
DirectionAngle.ElevationAngle
SupportQuantity
Positional
Parameter #27
Name
Invariant Latitude
ParameterKey
INVL
Description
The invariant latitude (in degrees) associated with the "Center_Epoch" of the data accumulation interval.
Units
degrees
ValidMin
-90.0
ValidMax
90.0
FillValue
-1.0E31
Support
Qualifier
DirectionAngle.ElevationAngle
SupportQuantity
Positional