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Laboratory for Atmospheric and Space Physics

Level 1

Level 1 Science Data Description

Version 1.0

Data Download

Here’s a link to download the level 1 data.

Description

Level 1 MinXSS data focuses on the science product and telemetry related to the science. The raw count spectrum from Level 0D is converted into irradiance units and NIST/SURF calibration applied. The nominal integrations are 10 seconds. The resultant array of structures (variable name = minxsslevel1_x123, for X123 data) is stored as an IDL saveset, which can be directly restored in IDL or read into python with the scipy.io.readsav function (see How to Load and Plot Data). The definition of the structure is provided in the table below.

What’s in Level 1 Data

The Level 1 data file for X123 is a variable minxsslevel1_x123, which is an array of anonymous structures (“anonymous structures” is IDL lingo that is the equivalent of dictionaries in other languages). Each element in the array is a point in time. The definition of the structure is provided in the table below.

Note: Bad data flag for bytes is 255 i.e. byte(-1). For strings it’s empty (‘’). For all other types it’s NaN.

Note: The primary science instrument is called the X123. The secondary science instruments are the SPS and XP. The attitude determination and control system (ADCS) is called XACT.

There are four main data structures, level1_x123 (X123 science observations), level1_x123_dark (eclipse data corresponding to the level1_x123 data), level1_xp (XP science observations), level1_xp_dark (eclipse data corresponding to the level1_xp data). There are also two ancillary structures, minxsslevel1_x123_meta and minxsslevel1_xp_meta, which essentially include the tag name descriptions listed in the tables in this document.

Level 1 structures definition

level1_x123 Structure

Tag Name Units Description
flight_model 1: MinXSS-1 in ISS orbit from 2016-05-16 to 2017-05-06

2: MinXSS-2 in 575 km sun-sync orbit from 2018-12-03 to present

irradiance photons/sec/cm^2/keV Float Array of 1024 elements. The photon flux array.
irradiance_uncertainty photons/sec/cm^2/keV Float Array of 1024 elements. The estimated uncertainty on the irradiance (photon flux array).
irradiance_low Same as Irradiance Float Array of 1024 elements. This version of the irradiance calculation does include solar photoelectron contribution and thus yields lower irradiance in the low energy bins below 1 keV.
irradiance_high Same as Irradiance Float Array of 1024 elements.  We recommend users use the Irradiance tag for science analysis and to restrict science analysis to above 0.8 keV to avoid where the irradiance_low and irradiance_high results diverge.
energy keV Float Array of 1024 elements.  The range is about 0 to 30 keV. The values < 0 are an artifact of the gain calibration, which results in a slight negative offset on the energy bins. 
spectrum_cps counts/s (cps) Float Array of 1024 elements. This is the count rate measured that is used to estimate the photon irradiance.
spectrum_cps_accuracy counts/s (cps) Float Array of 1024 elements. It provides estimate of the measurement accuracy which includes pre-flight calibration and measurement precision.
spectrum_cps_precision counts/s (cps) Float Array of 1024 elements. It provides an estimate of the measurement precision, which is dependent on the number of spectra used to create the count rate.
spectrum_cps_stddev counts/s (cps) Float Array of 1024 elements. If more than one integration time is used to create the spectra (Nx123 > 1), then this is the standard deviation of the binned spectra data. If only one spectrum is used, then this is equal to 0.
deadtime_correction_factor Float Float number indicating the number used to scale UP the spectra due to detector timer dead-time losses.
valid_flag Boolean Float Array of 1024 elements. Flag indicating if the irradiance value is considered “valid” after the conversion. 1 is considered a valid inversion; data corresponding to a valid_flag value of 0 should be analyzed with STRONG caution. Values with a value of 0 can vary by many orders of magnitude from the “true” value.
spectrum_total_counts counts Float Array of 1024 elements. This is the summed counts (per energy bin) measured over the all included integration periods used to create the data product.
spectrum_total_counts_accuracy counts Float Array of 1024 elements. It provides estimate of the measurement accuracy on spectrum_total_counts which includes pre-flight calibration and measurement precision.
spectrum_total_counts_precision counts Float Array of 1024 elements. It provides an estimate of the measurement precision on spectrum_total_counts, which is dependent on the total number of spectra used to create the count rate.
integration_time sec Integration time.  It can range from 10 sec for one X123 spectrum to about 60 sec.
number_spectra The number of spectra used to create the spectrum_cps and hence the irradiance quantities..
x123_fast_count counts/sec This is the spectrum summed count rate from the X123 fast channel.
x123_slow_count counts/sec This is the spectrum summed count rate from the X123 slow channel. This channel is used to create the X-ray spectra. The summation of the signal_cps array should equal the x123_slow_count value.
SPS_on Flag that says if the SPS unit is On or Off
SPS_sum fC SPS total signal from four quadrants
SPS_X degrees Offset from SPS optical center. The SPS_X_HK is also provided but it is not as accurate as the SPS_X tag.
SPS_Y degrees Offset from SPS optical center. The SPS_Y_HK is also provided but it is not as accurate as the SPS_Y tag.
longitude º

(degrees)

Spacecraft location relative to Earth
latitude
altitude km

(kilometers)

Spacecraft height above the Earth’s surface
sun_right_ascension º

(degrees)

Relative angle to sun as determined from ground computation based on TLE
sun_declination
earth_sun_distance AU

(astronomical units)

Earth’s orbit is an ellipse so irradiance changes slightly due to the 1/r2 dispersion of light
correct_au unitless Correction factor used to scale the irradiance to the annual averaged Earth-Sun distance (1 AU)
Time

[Time (structure) is same as used in Level 0D and is:

  1. fod
  2. hhmmss
  3. human
  4. iso
  5. jd
  6. sod
  7. spacecraftgpsformat
  8. yyyydoy
  9. yyyymmdd]
Time in a variety of formats

  1. Fraction of day
  2. Hours minutes seconds in day
  3. yyyy-mm-dd hh:mm:ss
  4. International standards organization time format (yyyy-mm-ddThh:mm:ssZ)
  5. Julian date
  6. Second of day
  7. Flight clock in GPS format
  8. Year day of year
  9. Year month day

level1_x123_dark Structure

Tag Name Units Description
flight_model 1: MinXSS-1 in ISS orbit from 2016/05/16 – ??

2: MinXSS-2 in 550 km ? LTDN sun-sync orbit from 2017/??/?? – ??

energy keV Float Array of 1024 elements.  The range is about 0 to 30 keV.
spectrum_cps counts/s (cps) Float Array of 1024 elements.
spectrum_cps_accuracy counts/s (cps) Float Array of 1024 elements. It provides estimate of the measurement accuracy which includes pre-flight calibration and measurement precision.
spectrum_cps_precision counts/s (cps) Float Array of 1024 elements. It provides an estimate of the measurement precision, which is dependent on the number of spectra used to create the count rate.
spectrum_cps_stddev counts/s (cps) Float Array of 1024 elements. If more than one integration time is used to create the spectra (Nx123 > 1), then this is the standard deviation of the binned spectra data. If only one spectrum is used, then this is equal to 0.
deadtime_correction_factor Float Float number indicating the number used to scale UP the spectra due to detector timer dead-time losses.
valid_flag Boolean Float Array of 1024 elements. Flag indicating if the irradiance value is considered “valid” after the conversion. 1 is considered a valid inversion; data corresponding to a valid_flag value of 0 should be analyzed with STRONG caution. Values with a value of 0 can vary by many orders of magnitude from the “true” value.
spectrum_total_counts counts Float Array of 1024 elements. This is the summed counts (per energy bin) measured over the all included integration periods used to create the data product.
spectrum_total_counts_accuracy counts Float Array of 1024 elements. It provides estimate of the measurement accuracy on spectrum_total_counts which includes pre-flight calibration and measurement precision.
spectrum_total_counts_precision counts Float Array of 1024 elements. It provides an estimate of the measurement precision on spectrum_total_counts, which is dependent on the total number of spectra used to create the count rate.
integration_time sec Integration time.  It can range from 10 sec for one X123 spectrum to about 60 sec.
number_spectra The number of spectra used to create the spectrum_cps and hence the irradiance quantities..
x123_fast_count counts/sec This is the spectrum summed count rate from the X123 fast channel.
x123_slow_count counts/sec This is the spectrum summed count rate from the X123 slow channel. This channel is used to create the X-ray spectra. The summation of the signal_cps array should equal the x123_slow_count value.
SPS_on Flag that says if the SPS unit is On or Off
SPS_sum fC SPS total signal from four quadrants
SPS_X degrees Offset from SPS optical center. The SPS_X_HK is also provided but it is not as accurate as the SPS_X tag.
SPS_Y degrees Offset from SPS optical center. The SPS_Y_HK is also provided but it is not as accurate as the SPS_Y tag.
longitude º

(degrees)

Spacecraft location relative to Earth
latitude
altitude km

(kilometers)

Spacecraft height above the Earth’s surface
sun_right_ascension º

(degrees)

Relative angle to sun as determined from ground computation based on TLE
sun_declination
earth_sun_distance AU

(astronomical units)

Earth’s orbit is an ellipse so irradiance changes slightly due to the 1/r2 dispersion of light
correct_au unitless Correction factor used to scale the irradiance to the annual averaged Earth-Sun distance (1 AU)
Time

[Time (structure) is same as used in Level 0D and is:

  1. fod
  2. hhmmss
  3. human
  4. iso
  5. jd
  6. sod
  7. spacecraftgpsformat
  8. yyyydoy
  9. yyyymmdd]
Time in a variety of formats

  1. Fraction of day
  2. Hours minutes seconds in day
  3. yyyy-mm-dd hh:mm:ss
  4. International standards organization time format (yyyy-mm-ddThh:mm:ssZ)
  5. Julian date
  6. Second of day
  7. Flight clock in GPS format
  8. Year day of year
  9. Year month day

level1_xp Structure

Tag Name Units Description
flight_model 1: MinXSS-1 in ISS orbit from 2016/05/16 – ??

2: MinXSS-2 in 550 km ? LTDN sun-sync orbit from 2017/??/?? – ??

xp_fc_background_subtracted DN/s Float. Background (dark diode) subtracted averaged signal from XP. The average is over the number of integrations (Nxp).
xp_fc_background_subtracted_uncertainty_accuracy femtoCoulombs/s (fC/s) Float. Estimate of the measurement accuracy on xp_fc_background_subtracted which includes pre-flight calibration and measurement precision.
xp_fc_background_subtracted_uncertainty_precision femtoCoulombs/s (fC/s) Float. Estimate of the measurement precision on xp_fc_background_subtracted, which is dependent on the total number of spectra used to create the count rate.
xp_fc_background_subtracted_stddev femtoCoulombs/s (fC/s) Float. If more than one integration time is used to create the signal (N > 1), then this is the standard deviation of the signal data. If only one integration time is used, then this is equal to 0.
x123_estimated_xp_fc femtoCoulombs/s (fC/s) Float. Estimated XP signal in fC/s from the measured X123 spectrum.
x123_estimated_xp_fc_uncertainty femtoCoulombs/s (fC/s) Float. Uncertainty on the estimated XP signal in fC/s from the measured X123 spectrum.
fractional_difference_x123_estimated_xp_fc Float Float. Fractional difference between the actual XP signal (xp_fc_background_subtracted) and the estimated XP signal from the measured X123 spectrum (x123_estimated_xp_fc).
number_xp_datum Integer Number of integration periods to create the XP data.
Time

[Time (structure) is same as used in Level 0D and is:

  1. fod
  2. hhmmss
  3. human
  4. iso
  5. jd
  6. sod
  7. spacecraftgpsformat
  8. yyyydoy
  9. yyyymmdd]
Time in a variety of formats

  1. Fraction of day
  2. Hours minutes seconds in day
  3. yyyy-mm-dd hh:mm:ss
  4. International standards organization time format (yyyy-mm-ddThh:mm:ssZ)
  5. Julian date
  6. Second of day
  7. Flight clock in GPS format
  8. Year day of year
  9. Year month day

level1_xp_dark Structure

Tag Name Units Description
flight_model 1: MinXSS-1 in ISS orbit from 2016/05/16 – ??

2: MinXSS-2 in 550 km ? LTDN sun-sync orbit from 2017/??/?? – ??

xp_fc_background_subtracted DN/s Float. Background (dark diode) subtracted averaged signal from XP. The average is over the number of integrations (Nxp).
xp_fc_background_subtracted_uncertainty_accuracy femtoCoulombs/s (fC/s) Float. Estimate of the measurement accuracy on xp_fc_background_subtracted which includes pre-flight calibration and measurement precision.
xp_fc_background_subtracted_uncertainty_precision femtoCoulombs/s (fC/s) Float. Estimate of the measurement precision on xp_fc_background_subtracted, which is dependent on the total number of spectra used to create the count rate.
xp_fc_background_subtracted_stddev femtoCoulombs/s (fC/s) Float. If more than one integration time is used to create the signal (N > 1), then this is the standard deviation of the signal data. If only one integration time is used, then this is equal to 0.
x123_estimated_xp_fc femtoCoulombs/s (fC/s) Float. Estimated XP signal in fC/s from the measured X123 spectrum.
x123_estimated_xp_fc_uncertainty femtoCoulombs/s (fC/s) Float. Uncertainty on the estimated XP signal in fC/s from the measured X123 spectrum.
fractional_difference_x123_estimated_xp_fc Float Float. Fractional difference between the actual XP signal (xp_fc_background_subtracted) and the estimated XP signal from the measured X123 spectrum (x123_estimated_xp_fc).
number_xp_datum Integer Number of integration periods to create the XP data.
Time

[Time (structure) is same as used in Level 0D and is:

  1. fod
  2. hhmmss
  3. human
  4. iso
  5. jd
  6. sod
  7. spacecraftgpsformat
  8. yyyydoy
  9. yyyymmdd]
Time in a variety of formats

  1. Fraction of day
  2. Hours minutes seconds in day
  3. yyyy-mm-dd hh:mm:ss
  4. International standards organization time format (yyyy-mm-ddThh:mm:ssZ)
  5. Julian date
  6. Second of day
  7. Flight clock in GPS format
  8. Year day of year
  9. Year month day