TWINS 1 neutral-atom spectrometer level-1 magnetospheric images and image movies at full (9 energy steps and 15 minute) resolution. Images have been smoothed using a technique that provides approximately uniform statistics across the image. Each image has 4x4 degree angular resolution and includes 15 minutes of data. These images are derived on the ground from direct events measurements of the time of flight and detection location on the anode for individual ENAs. Each image has 4x4 degree angular resolution and includes 15 minutes of data. The first dimension of the image represents the scan angle in instrument coordinates. In this system the azimuthal attitude vector points to +90 degree scan angle. The second is the imaged angle, where 90 degrees is the central viewing angle of the instrument and the direction of the polar attitude vector.

Epoch

Satellite ID number (1=twins1 or 2=twins2)

TWINS smooth image of neutral atom flux for all energies

Statistically smoothed TWINS image of flux per energy at 1 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 4 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 8 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 12 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 16 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 20 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 25 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 30 keV energy, in units of (cm^2 sr s eV)^-1.

Statistically smoothed TWINS image of flux per energy at 50 keV energy, in units of (cm^2 sr s eV)^-1.

The per-pixel sweep count is the number of times a given pixel was sampled by the instrument during the time taken to make the image. This value is only a function of longitude (actuation angle), and so is the same for all latitude (imaged) pixels at a given scan (actuation) angle. The value is nominally the same for all pixels in an image, and is the same as the number of sweeps in the image. Differences from this value are due to errors in either actuator motion or transmission of data from agiven direction.

Target value for the number of counts per pixel used in the smoothing algorithm. This value can vary by energy.

Array of energy values (in keV) for the smoothed images. Nominally 1, 4, 8, 12, 16, 20, 25, 30, and 50 keV.

[LIST ONLY] version of the smoothing algorithm used to create the TWINS_SMOOTH_IMAGE.

[LIST ONLY] units of smoothed twins image

Longitude (deg) at the middle of the first pixel. For 4 deg pixel_size this is nominally -88 degrees.

Longitude (deg) at the middle of the last pixel. For 4 deg pixel_size this is nominally -92 degrees.

Latitude (deg) at the middle of the first pixel. For 4 deg pixel_size this is nominally 4 degrees.

Latitude (deg) at the middle of the last pixel. For 4 deg pixel_size this is nominally 88 degrees.

The pixel size in the imaging (polar) direction.

The pixel size in the scan (longitudinal) direction.

Start time of the image and the stop time of the image

Start time of the image and the stop time of the image in Modified Julian Date (MJD)

TWINS smoothed image error image for all energies. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 1 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 4 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 8 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 12 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 16 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 20 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 25 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 30 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

TWINS smoothed image error image at 50 keV energy. The error in the flux for each pixel is given by sqrt(counts) / counts using the counts included in each pixel of the image.

A flag that identifies when attitude and ephemeris information are available. A value of 0 indicates data are available; a value of 1 indicates that either attitude or ephemeris information is not available for a given time interval.

The change (in degrees) of the spacecraft attitude vector over the time required to make the given image.

The average spacecraft location vector over the time interval of the image in ECI coordinates (cartesian XYZ components).

The average polar pointing unit vector over the time interval of the image in ECI coordinates (Cartesian XYZ components). The polar attitude vector points to 90 degree instrument polar (imaged) angle.

The average azimuthal pointing unit vector over the time interval of the image in ECI coordinates (Cartesian XYZ components). The azimuthal pointing vector points to +90 degree instrument scan angle.

The average Sun unit vector over the time interval of the image in ECI coordinates (Cartesian XYZ components).

The average geomagnetic dipole unit vector over the time interval of the image in ECI coordinates (Cartesian XYZ components).

The average spacecraft location vector over the time interval of the image in SM coordinates (Cartesian XYZ components).

The average polar pointing unit vector over the time interval of the image in SM coordinates (Cartesian XYZ components). The polar attitude vector points to 90 degree instrument polar (imaged) angle.

The average azimuthal pointing unit vector over the time interval of the image in SM coordinates (Cartesian XYZ components). The azimuthal pointing vector points to +90 degree instrument scan angle.

The average Sun position unit vector over the time interval of the image in SM coordinates (Cartesian XYZ components).

The average geomagnetic dipole unit vector over the time interval of the image in SM coordinates (Cartesian XYZ components).

Spacecraft radial distance (in Earth radii) from the center of the Earth.

Spacecraft latitude in SM coordinates

The McIlwain L-Shell at the spacecraft location assuming a dipole magnetic field model and using SM coordinates.

Spacecraft magnetic local time in SM coordinates.

Array of energy values (in keV) for the images. Nominally 1, 4, 8, 12, 16, 20, 25, 30, and 50 keV.

0 for a Differential Energy Flux image. 1 for an All Energies image

saveset_version

[LIST ONLY] Start and stop times of the image, along with the selected number of sweeps.

[LIST ONLY] units of raw twins image

[LIST ONLY] Software version

[LIST ONLY] Time image was created

TWINS raw image of flux for all energies

TWINS raw image at 1 keV energy, in units of (cm^2 sr s eV)^-1.

TWINS raw image at 4 keV energy, in the same format as the 1 keV image.

TWINS raw image at 8 keV energy, in the same format as the 1 keV image.

TWINS raw image at 12 keV energy, in the same format as the 1 keV image.

TWINS raw image at 16 keV energy, in the same format as the 1 keV image.

TWINS raw image at 20 keV energy, in the same format as the 1 keV image.

TWINS raw image at 25 keV energy, in the same format as the 1 keV image.

TWINS raw image at 30 keV energy, in the same format as the 1 keV image.

TWINS raw image at 50 keV energy, in the same format as the 1 keV image.

TWINS error image for raw image at all energies. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 1 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 4 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 8 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 12 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 16 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 20 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 25 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 30 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.

TWINS error image for raw image at 50 keV energy. The error in the flux for each pixel is based on the error in the fit of flux vs energy used to determine the flux value given in the primary image.